View Full Version : A SBC tripower setup, school me


Roothawg
08-04-2007, 08:10 AM
I have been reading the old posts around here lately on sbc tripower setups. I see a lot of them on ebay etc bringing huge money.

I know they still make the intakes but can you go out and just buy rebuilt carbs? Is there a book that can tell me how to convert the other carbs?

I am confident I can build a nicer set of linkage that what I can buy, so that just leaves the carb issues. I don't see 1,000 bucks worth of hassle, but that's what they are bringing.

I am not hung up on 2, bolt 3 bolt or what ever.........not a "period correct" piece. I just need the visual impact on my 36.

Thanks

pecker head
08-04-2007, 08:15 AM
I was just looking at vintage speed lot of info . You can also get the kit from Speedway to make correct carbs .

60 Belair
08-04-2007, 08:15 AM
www.vintagespeed.com (http://www.vintagespeed.com) ck out the catalog everything you need and instructions

Roothawg
08-04-2007, 08:16 AM
I have heard bad things about vintage speed. Maybe just using them for info would be a good idea.

Here's the Speedway link you mentioned. I would have never thought about them. Thanks

http://www.speedwaymotors.com/p/1647,,_Rochester-TriPower-Base-Kit.html?itemNo=tri%20power%20carb

pecker head
08-04-2007, 08:21 AM
I have a freind in Waco that used the Speedway kit , he say's it's the best . Im running a Hotrod Carberation set up from the late 80's on my sedan , works great .

7&7
08-04-2007, 08:51 AM
In Rod and Custom a few years back they had a article on how to modify carbs for tri power. We built a set for my buddies nailhead off the article and he loves them. You can get rochester 2gc from the junk yard real cheap and just modify the bases. The same article had modifications for 94's-97's-2gcs. If you cant find the article give me a PM and I will try to find it. The article was from around 2002 or so. Did you ever get a waterpump figured out for the 265. I found a cool Leeman crank driven pump from a sprint car for $70 with the timing cover at a circle track swap meet. Just an idea. Good luck.

18n57
08-04-2007, 09:59 AM
Rochester 2 barrels can be easily converted with Speedway parts, but you'll need earlier style with fuel inlet pointing to the side, later ones point forward and with three in a row you'll have clearance problems. I have the R/C article if need it . I'm running a 265 in my '34, what's the water pump problem?

52plybizcoupe
08-04-2007, 10:23 AM
just remember you cant youse just three of the same carb
the end carbs are jetted different and set up different in some cased (ie. no power valves in end carbs and no accelerator pump on end s to)

Jimv
08-04-2007, 12:16 PM
I converted "primary" carbs to"secondaries" from a article in R&C a few years ago without the speedway kits, made my own linkage, used a spring for a spacer to give mne the proper "travel".I'll try & get a picture posted.
JimV
PS.HEY "peckerhead28" You spelled " TURD" wrong!! ya peckerhead!!lol

Jimv
08-04-2007, 12:51 PM
here ya go:

dickster27
08-04-2007, 04:14 PM
I'm sure you all do know that Speedway's carburetor parts and kits come from Charlie at Vintage Speed? Actually, they can be purchased from V/S for less money. Just for your information. It really isn't really necessary to use side exit 2G's as Olds, Caddy, and Pontiac used front exit, as Have I for years with no clearance issues when the right fittings are used. You just need to decide how valuable your time is........$300 for a conversion kit from Vintage Speed, $229 for a kit from Eelco, Inc., or $75 for the parts to do it yourself. There you have it.

mistoo
08-04-2007, 05:24 PM
I am in the beginning stages of putting together a 3x2 setup for SBC. Can anyone tell me about vacuum pressure and 3x2 ? Is there anything to take into account when putting the system togeather according to how much vacuum pressure my motor has at idle and at throttle ?

Jeff Norwell
08-04-2007, 07:52 PM
Root
give my friend Larry Fulton a ring.
His company is Automotion....he has all you need and will talk to you.
He has cores/do it yourself kits or the full monty..... complete ready to go inductions

http://www.hotrodcarbs.com/


He has been a great help and a good friend.(and his wife won't start screaming at ya either!:) )

arnnz
08-04-2007, 08:53 PM
Try this site . These look good
http://www.carburetion.com/tripower.htm

Tudor
08-04-2007, 09:32 PM
I am in the beginning stages of putting together a 3x2 setup for SBC. Can anyone tell me about vacuum pressure and 3x2 ? Is there anything to take into account when putting the system togeather according to how much vacuum pressure my motor has at idle and at throttle ?

its either vacuum or pressure - :)

you need some vacuum to suck the gas at idle

I had a real big cam and couldn't get my 3 -2 's to ildle. I opened up the idle circuit tubes and couldn't get it to go. I ended up getting a slightly smaller cam (xe 268) and it idled.

whitewallslick
08-04-2007, 10:13 PM
What cars/engines can the Rochester carbs be found on?

pecker head
08-05-2007, 10:09 AM
I converted "primary" carbs to"secondaries" from a article in R&C a few years ago without the speedway kits, made my own linkage, used a spring for a spacer to give mne the proper "travel".I'll try & get a picture posted.
JimV
PS.HEY "peckerhead28" You spelled " TURD" wrong!! ya peckerhead!!lol
My bad , I fixed it .:D

pecker head
08-05-2007, 10:13 AM
What cars/engines can the Rochester carbs be found on?
Any chevy from mid 50's to early 70's & other GM cars.

Unclee
08-05-2007, 10:54 AM
Actually, somewhere in there they went to a larger base pattern. I think for sure that all 350's w/2bbl were large.

Roothawg
08-05-2007, 03:42 PM
Thanks guys. I am going to have to read all of these posts and check each link. Valuable information.

1oldtimer
08-10-2007, 12:28 AM
you can use the small fuel inlet front feed or the side feed, the big front inlet is the big base and is waaay to much for a mild build.......and yes they need to be the same cfm's. built one with 3 side feeds for a friends car and i have the speedway kit for mine (havent used it yet), at the time the speedway kit was cheaper then vintage speed and more reliable (yes they are from vintage speed).
vintakes on here builds kits and has a nice webpage:
http://www.vintakes.com/custom.html

Motochris
08-23-2007, 02:40 PM
vintakes on here builds kits and has a nice webpage:
http://www.vintakes.com/custom.html

That link doesn't work.

I too want a 3x2 set for my truck. Seems like most guys want WAY too much for an old used set. Why spend $1000 on a set that needs work when you can get them new for $1500 or so?
Anybody got any leads on any decent complete used sets?

3Deuce40
08-23-2007, 03:01 PM
Since were on the topic, has anybody used the "brand new" Strombergs? I've seem them and they look really good, just not sure there worth the $400 each, but then again, maybe they are.

HEATHEN
08-23-2007, 03:29 PM
The small base Rochester 2GC carbs were used on every 265, 283, and most of the 307s, as well as the 210hp 327s in early Camaros. They can also be found on 215 and 300 Buick V8s of the '60s. If you luck upon a '58 or '58 Olds or Pontiac (or any 348) tripower setup, you will find a primary and two secondary carbs, all small base. Pontiac went to large secondary carbs in '59.

stoggie
08-23-2007, 03:43 PM
I had a real big cam and couldn't get my 3 -2 's to ildle. I opened up the idle circuit tubes and couldn't get it to go. I ended up getting a slightly smaller cam (xe 268) and it idled.

How big of cam? I am working on my set up and was planning to run with the Comp 280 cam. I have a 268 in my Malibu with the Blower and it is barely enough. I was concerned about the 3x2 set up for this motor?
There is an article/tech post posted by Vintakes. I helped him fix the text. I saved the article but seemed like I needed more info to understand.
I was also thinking the R&C article was pretty vague on the 2Gs. I have several carbs I just need to re-work for the same set up.

stoggie
08-23-2007, 03:45 PM
here is the vintake link: http://www.jalopyjournal.com/forum/showthread.php?t=77680

Tudor
08-24-2007, 06:09 AM
How big of cam? I am working on my set up and was planning to run with the Comp 280 cam. I have a 268 in my Malibu with the Blower and it is barely enough. I was concerned about the 3x2 set up for this motor?
There is an article/tech post posted by Vintakes. I helped him fix the text. I saved the article but seemed like I needed more info to understand.
I was also thinking the R&C article was pretty vague on the 2Gs. I have several carbs I just need to re-work for the same set up.

Stogie I went from a 292 to a 268 and it worked. Lost 70 HP on top end between the cam and 4 barrel - but still run 13.3's. It has way more low end. Better burn outs for sure.

Crease
08-24-2007, 08:11 AM
Root,

As you already know, CP builds the crappiest carb on the planet (it's all been said before). If I recall correctly, you just eliminate the idle circuit and your good to go. Some folks say to eliminate the power valve, others swear you should keep it. Mine are eliminated. You don't need the choke on 1 and 3, but doesn't hurt to keep it. All you really need to do is contact Rudolph Faltermeier. He's as old as a stromberg and as reliable as a Rochester. :) Rudolph builds Holley 94s VERY reasonably. He is extremely knowledgeable in setting up a tri power and willing to share the info. I have sent atleast 5 people to him and all have been very satisfied. If you need Rochesters, his son does those.
Rudolf Faltermeier
150 Rock Bridge Rd
Spartanburg, SC 29307
864-463-6052

Irish Dan
08-24-2007, 08:34 AM
Go with Hotrodcarbs.com. Larry Fulton, the owner, is the one Edelbrock recommends exclusively.

tommy
08-24-2007, 09:35 AM
OK I'm a poser...that said...I used the original carb from my 71 Camaro donor engine. I picked up some 20 dollar core carbs for the blocked off end carbs. It's a cost/benefit ratio for me. 3 Deuces are eye candy. If you really want to go fast get something else. You'll have to fudge the linkage or remove the butterflies on the end dummy carbs, but it will perform just like a 71 Camaro with ZERO hassles. No vacuum leaks or flooded carbs. If it screws up in BFE you ask for a carb for a 71 Camaro, 307, automatic with A/C. The kid punches it in the computer and voila you're golden.

Yeah there will be some whining about having non functional carbs (don't tell them!) from some people but do they really drive? Sure it can be done for an ass load of money and probably an ass load of trouble dialing it all in. Is the few times that you ever open it up really worth all that?...not to me. JMHO

It's probably a sign of old age but after a while you just want to drive it without hassles. If you shop right you should be able to put together a good looking intake system for about 400 bucks. That leaves another 600 for other stuff.

Tudor
08-24-2007, 10:02 AM
OK I'm a poser...that said...I used the original carb from my 71 Camaro donor engine. I picked up some 20 dollar core carbs for the blocked off end carbs. It's a cost/benefit ratio for me. 3 Deuces are eye candy. If you really want to go fast get something else. You'll have to fudge the linkage or remove the butterflies on the end dummy carbs, but it will perform just like a 71 Camaro with ZERO hassles. No vacuum leaks or flooded carbs. If it screws up in BFE you ask for a carb for a 71 Camaro, 307, automatic with A/C. The kid punches it in the computer and voila you're golden.

Yeah there will be some whining about having non functional carbs (don't tell them!) from some people but do they really drive? Sure it can be done for an ass load of money and probably an ass load of trouble dialing it all in. Is the few times that you ever open it up really worth all that?...not to me. JMHO

It's probably a sign of old age but after a while you just want to drive it without hassles. If you shop right you should be able to put together a good looking intake system for about 400 bucks. That leaves another 600 for other stuff.

my 3-2 set up hauls and is ZERO trouble. Just set it up like GM did. Use the right end carbs. Lots of ladies put lots of miles on cars with 3-2 set ups without any hassels

stoggie
08-31-2007, 01:46 PM
Pushing this back up to see if we can be further enlightened...

Mopar34
08-31-2007, 02:21 PM
What cars/engines can the Rochester carbs be found on?


I have them on my 57 Olds 371, but unless you are willing to risk lead poisoning, I better not catch you in my garage. :eek: :D :D
<!-- / message --><!-- sig -->

Roothawg
08-31-2007, 02:28 PM
Thanks Crease. I'll check him out.

Notorious
08-31-2007, 04:24 PM
my 3-2 set up hauls and is ZERO trouble. Just set it up like GM did. Use the right end carbs. Lots of ladies put lots of miles on cars with 3-2 set ups without any hassels
I agree, there's no reason that it can't work reliably and drive as well as anything else. My only 3-2 experience was with a 440-6 '70 Cuda over 30 years ago. The car was a few years old at that time. I rebuilt the Holleys and never had another bit of trouble out of them. The damn thing even got 15+ mpg on the highway too, unbelievable to me at the time. It never bogged, stumbled, leaked or anything. And when those two end 500 cfm carbs kicked in, hang on! It would literally fry the tires from a 70 MPH punch on any street tires. That was a damned fun car! :cool: Pure stock, the six pack Cudas were quicker than the Hemi ones.

Prop Strike
08-31-2007, 04:59 PM
You cant beat Webber's for driveability and performance in my opinion. Super easy for maintenance and tuning too. Too bad we're poor. Only setups I see are usually new, always big buck.
Caution SBC porn http://www.inglese.com/Catalog/Inglese%20Product%20Brochure%20NG1816.pdf

Notorious
08-31-2007, 05:22 PM
You cant beat Webber's for driveability and performance in my opinion. Super easy for maintenance and tuning too. Too bad we're poor. Only setups I see are usually new, always big buck.
Caution SBC porn http://www.inglese.com/Catalog/Inglese%20Product%20Brochure%20NG1816.pdf

Webers are awesome. Once you gain an understanding of the basics, there's really no carb that can compare. They're actually very easy to tune, simple and are quite efficient when done right. In a given model, you can even dial in the CFM within that particular design's range.

MIKE-3137
08-31-2007, 06:36 PM
The setup on my 327 has '56 or 57 Olds J-2 factory tripower carbs on an offy manifold. You may find these a bit cheaper than other factory 2G tripower carbs, not to mention buying cores and then converting them to tripowers. These are a bit different from other rochesters I have seen. All three are front inlet 2G Rochesters but have a small 1/8 pipe thread fittings, and the center carb has a dome shaped vent, The good part is the end carbs already have the thicker butterflies with extended shafts, and no idle circuits.

theHIGHLANDER
08-31-2007, 07:47 PM
I recently dialed in a set on a warmed over 65 GTO. Original carbs on a stroker motor. The 1st guy to set them up had all of them open way too early and the owner was complaining about drivability. If you look at the stuff for a few minutes it's really no big deal. So how did it run? The car can drive well over 70mph on just the center and you can feel the "stop" effect of the leading edge of the ends getting ready. Open em up and it was like passing gear in an automatic. Tons of power and makes you smile so big ya gotta turn yer head to finish it. I love tri power.

Thought you'd like a pic...but don't hold the moroso covers against me...that's what the guy wanted. I think it needs some offys don't you?

LUX BLUE
08-31-2007, 09:31 PM
Check this out.

Ames performance (The pontiac guys) sell tri power linkage that is built for Poncho stuff...but after having dealt with many,many multi carb set ups, they are as easy to adapt to another carb set as anything else...and it actually works and looks "right" doing it.

I would sooner staple my scrotum to a moving car than buy ANYTHING from C.P. Suffice to say my Experiences with his admittedly very pretty carbs has been less than positive. (Wow! That was alot of fire!)

and finally, check out B.F.I.C. for end carbs-I'm talking about 2cg's, and 2g's here...but if you wanna make power and look good doing it, in my opinion, they're the way to go. 20 billion G.T.O.'s can't be wrong!

Crease
08-31-2007, 10:21 PM
Check this out.

Ames performance (The pontiac guys) sell tri power linkage that is built for Poncho stuff...but after having dealt with many,many multi carb set ups, they are as easy to adapt to another carb set as anything else...and it actually works and looks "right" doing it.

I would sooner staple my scrotum to a moving car than buy ANYTHING from C.P. Suffice to say my Experiences with his admittedly very pretty carbs has been less than positive. (Wow! That was alot of fire!)

and finally, check out B.F.I.C. for end carbs-I'm talking about 2cg's, and 2g's here...but if you wanna make power and look good doing it, in my opinion, they're the way to go. 20 billion G.T.O.'s can't be wrong!

I agree with you regarding the 2gc's. I love my 94s, but I have often considered swapping for a set of leak free Rochesters. That nut thing was funny! :)

zx7rcr
09-07-2007, 09:43 AM
Check out www.hotrodcarburetion.net (http://www.hotrodcarburetion.net)

We have built these for over 30 years now.

Dan Hay
09-08-2007, 01:36 AM
I'm building on a budget, and would love 3 deuces on my 38 but... how do three rebuilt carbs... carbs that are a dime a dozen used...cost $1000?? I guess carb. shop rates are $100/hr.

You know that if I had the dough they'd be in a UPS truck as we speak...

Jimv
09-08-2007, 06:40 AM
I'm building on a budget, and would love 3 deuces on my 38 but... how do three rebuilt carbs... carbs that are a dime a dozen used...cost $1000?? I guess carb. shop rates are $100/hr.

You know that if I had the dough they'd be in a UPS truck as we speak...

Kits are about $20 each & do it yourself!! I have about $200 in my setup!!But i got the manifold cheap( $85) swap meet carbs & someone gave me one of them, i made my linkage( See my earlier post) And i made my outboards into secondary ones.
I'll help ya over the phone & by e-mailing you pictures if ya want to call me let me know
JimV

Unclee
09-08-2007, 09:39 AM
The only reason anyone would have problems from a 3-duece set up with progressive linkage is if they didn't use them and the fuel gets stale in the end carbs, Hell, Holley four barrels had the same problem.

rpol7966
10-18-2007, 08:16 AM
I'm gathering the parts to put together a 3X2 setup for my 327 SBC. Could someone provide a copy of the Rod & Custom article for the carb conversion.
I've picked up several Rochesters for parts so I can put together what I need. Still looking for an intake though.
Any help would be appreciated.

PRIMERDAVE
10-18-2007, 09:09 AM
i have a 3X2 sut up in my daily driver 65' chev trk.....283 bored 30 over and a nice mild next to wild Crower cam ....once it was dialed in I've had zero problems and still get 15 to 17 mpg depending on much I get into it....and yes i'ts hard not to get into it....oh and I got the set up from V speed ....the only problem i had with them was getting them on the phone to order the damm thing....after that ,I got it in the four weeks he said it would take....

and if your gonna run a fake tri power you might as well run one of them fake Blower or Hilborn set ups.....

slackerhotrod
02-07-2008, 08:43 AM
I got my set up ready to run from vintage speed, sweeeeet

http://www.vintagespeed.com/carbs.htm

slacker

strombergs97
02-07-2008, 06:21 PM
Ready for a SBC intake..simple and functional..Nothing fancy done to these all complete..Just tune them in..
Duane.

BELLM
02-08-2008, 11:17 PM
Chris talk to Reggie. He has 3 2GCs on the 34 he drives everywhere, I beleive he just closed the air mixture screws on the end carbs, been running several years. I have picked up Delco rebuilt stock 2GCs at Texas swap meets, bought 3 matching in boxes sealed in plastic for $160, next year bought 3 more $180, last time I saw him he was getting $70 each but his supply was drying up. He will probably be @ the Conroe winter swap next weekend, if you are interested PM me your phone #, if he is there I can call you & let you know how much he is getting now and can pick you up 3 if you want them.

JOECOOL
02-09-2008, 02:38 PM
I am trying to piece a setup together also .I don't know what the manifold is as the #'s are ground off. I'm useing 55-57 Pontiac carbs that a friend had.
Kits thru NAPA were $15 ,linkage looks to be less than $30. The carbs I have are front inlet but it looks easy to get the lines on .
The Carbs have a large piece that the linkage side hooks up on ,looks easy to adapt linkage.

Abomination
02-09-2008, 03:00 PM
You can use about any 3 carbs. Leave the center stock, and make sure that no air or fuel gets through the outboard ones when the butterflies are closed or at idle by either filing the butterflies so that when they're closed they're closed, and/or epoxying the bleeder screw holes. If you can get the outboard carbs to close tight enough, you don't even need to epoxy the bleeder screw holes. But remember, although this method lets you use any 3 carbs, it's trial and error, as those outboard carbs are an air or fuel leak waiting to happen at idle.

~Jason

1oldtimer
02-09-2008, 03:12 PM
the link works:
www.vintakes.com/custom.html if it doesn't the try www.vintakes.com then click on custom page.
this isn't rocket science, the hardest part is getting the 2 outer carbs to act right (seal) the linkage is cake. my friends model A, not pretty but it works. it was round bar stock, washers, a drill, a vice, a tap and a welder.

glendale
02-09-2008, 03:15 PM
to far from me but this may help you guys. and if they are the carbs i'll take 3 thanks.
http://slo.craigslist.org/zip/568548938.html

Abomination
02-09-2008, 05:32 PM
You know, how come nobody experiments with weird Carters? They're cheap enough to build, and almost free - if somebody could "crack that nut", so to speak, it could save a lot of folks some money...

G V Gordon
02-09-2008, 05:44 PM
Root, Issue #12 of Rod and Kulture has pretty good article on this conversion. Give me a call if you cant find it.. Its the one with the Rebel Reaper Willys on the front.
GV

3x2rocket
02-09-2008, 10:36 PM
Its easy and does not have to cost a grip! Mine are from a 57' Olds and do have the proper end carbs with no idle circuit. It is way faster than the 4bbl and trouble free once its set up. All you need are 3 buildable cores which you can get cheap, and 3 kits. Its easy to block out the idle circuits on the ends by cutting off the tip of the needle then put some teflon paste on the threads put them back and viola. As far as vacuum leaks go you can use some thinned out jb weld and paint the inside of the base where the blades touch with it, let it become semi-hardened then make an impression by closing it and no more vacuum issues without using the thick and hard to find blades. Jetting is easy enough, typically the ends are a few sizes smaller and you don't need accelerator pumps or power circuits, the ends are slaves. Then you have the fun of tuning your progressive linkage by finding out where you want your secondaries to kick in, I do this by flooring it and adjusting after my runs.

DirtyThirty
02-09-2008, 11:04 PM
O.K....
Here goes: I'm ducking already to avoid the pending shitstorm, but, I am not a carb genius...This has been on mind off and on...maybe I'm thinking bass-ackwards, but:

Why NOT let it idle on all three carbs?
bring the secondaries in progressively, with the linkage functioning properly, but, leave the idle circuits working, and adjustable, in the end carbs?
Won't that negate any possible vaccum leak/lean problems if the end carbs butterflies don't quite fully close?
Would you not have more even dispersement of air/fuel, at idle, than with only the center?
somebody wanna 'splain?

Abomination
02-10-2008, 12:20 AM
That is f'n genius - seriously!

Now, why didn't I ever think of that? :confused:

~Jason

viola. As far as vacuum leaks go you can use some thinned out jb weld and paint the inside of the base where the blades touch with it, let it become semi-hardened then make an impression by closing it and no more vacuum issues without using the thick and hard to find blades.

aerorocket
02-10-2008, 12:43 AM
Carburetors require a vacuum signal to operate properly; the stronger the better. Unlike fuel injection, carburetors must have a vacuum signal from the engine to flow fuel through the venturis. By using all three carbs you are in effect dividing that signal by 3. This is why carburetors are many times troublesome at low rpm's with big overlap cams. [low vacuum signal]

Abomination
02-10-2008, 07:53 AM
Just woke up this morning and re-read this - man... that's some good stuff, right there.

I am curious about turbulence - does the small lip created by the JB Weld "shelf" mess up airflow in the bore enough to make any noticable difference at all?

~Jason

viola. As far as vacuum leaks go you can use some thinned out jb weld and paint the inside of the base where the blades touch with it, let it become semi-hardened then make an impression by closing it and no more vacuum issues without using the thick and hard to find blades.

DirtyThirty
02-10-2008, 08:54 AM
Carburetors require a vacuum signal to operate properly; the stronger the better. Unlike fuel injection, carburetors must have a vacuum signal from the engine to flow fuel through the venturis. By using all three carbs you are in effect dividing that signal by 3. This is why carburetors are many times troublesome at low rpm's with big overlap cams. [low vacuum signal]


I understand that a carb works on engine vaccum, I should have said I am not a carb expert, however, I DO understand the theory. I do noy have a lot of experience with multi-carb set-ups, nor am I a "super-tuner".
Other than dividing the signal amongst three carbs, why is this way of doing it "wrong" as I'm told by everyone. If it idles, it enrichens the mixture when the secondary carbs come in, they are at wot at precisely the same time as the primary carb, and they return to idle, why is it a problem?

I'm wondering if the disadvantages ( potential ones, such as with a long duration cam, or long, big runners? ) exist, or at least are noteworthy anyway, with a mild motor, with a typical tri-power intake, which is not exact cavernous and free flowing.

nexxussian
02-10-2008, 03:55 PM
So, 3X2rocket, what are you using to thin the JB Weld?

Tudor
02-10-2008, 07:03 PM
I understand that a carb works on engine vaccum, I should have said I am not a carb expert, however, I DO understand the theory. I do noy have a lot of experience with multi-carb set-ups, nor am I a "super-tuner".
Other than dividing the signal amongst three carbs, why is this way of doing it "wrong" as I'm told by everyone. If it idles, it enrichens the mixture when the secondary carbs come in, they are at wot at precisely the same time as the primary carb, and they return to idle, why is it a problem?

I'm wondering if the disadvantages ( potential ones, such as with a long duration cam, or long, big runners? ) exist, or at least are noteworthy anyway, with a mild motor, with a typical tri-power intake, which is not exact cavernous and free flowing.

I am going to take a stab at an answer. Basically the motor will get the right air/fuel ratio to idle from one carb. When you have all three idling the engine, you've got 3 times the air and gas, and the vacuum cut to each carb. Those rochesters rely on the vacuum to pull the idle circuit fuel out of little tubes in the carb. Cut the vacuum, cut getting any fuel on the idle circuit. Then you end up opening the throttle blades and end up with way too much air. People can get them to run, but they idle way rich and probably aren't really idling on the idle circuit anymore. Its just simple to do it the same way GM did it.

3x2rocket
02-10-2008, 07:25 PM
I cannot take credit for this trick as Ross (Ross Racing Engines) in Ohio taught it to me over the phone. I used Lacquer thinner and a very small paintbrush. First I closed the blades on the base and traced with a sharpie where they sit flush. Then I mixed the jb and thinner on a piece of cardboard and painted a very thin layer over my pen marks, I also did a test spot on the cardboard to check for tackiness. What you want is just a little soft but not sticky. I also applied a very thin layer of Marvel Mystery oil to the blades to help keep the jb/thinner mixture from sticking. After it no longer felt sticky, (this will take awhile, thinning it out seems to increase hardening time) I forced the blades closed making a nice clean impression, then opened it and left town for two days. When I came home it was hard and I could barely see a spec of light next to the shafts looking through the base (Don't get it on the shafts) It may not completely seal but it worked well enough! My car now idles at 900rpm with a lopey Isky cam, (down from 1200rpm).

Honestly this took 4 tries till I got it right, it was a pain in the ass! takes a lot of patience and do a test swab of the mixture at as close to the same thickness on your base as possible then test it before closing the blades, (my failures were due to sticking on the blades due to my impatience, as well as applying way too much the first two times).

As far as impeding performance, there was no noticeable change in acceleration at all. You want it as thin and smooth as possible! and thin means very little turbulence or impedance of air flow. Apparently they did this from the factory back in the day with some mystery compound.

Funny thing is, I have the really thick blades but I bought the long shafts for progressive linkage and they don't fit in them.

Roothawg
02-10-2008, 09:17 PM
Sorry BellM, I hadn't read this until now. Thanks for the offer, I am leaning towards the 4 barrel even though it doesn't look as cool. I am still studying though.

GV, thanks for the offer. I may need to get a copy if possible. I am going to look at hastings and see if they have it yet.

DirtyThirty
02-10-2008, 09:42 PM
I am going to take a stab at an answer. Basically the motor will get the right air/fuel ratio to idle from one carb. When you have all three idling the engine, you've got 3 times the air and gas, and the vacuum cut to each carb. Those rochesters rely on the vacuum to pull the idle circuit fuel out of little tubes in the carb. Cut the vacuum, cut getting any fuel on the idle circuit. Then you end up opening the throttle blades and end up with way too much air. People can get them to run, but they idle way rich and probably aren't really idling on the idle circuit anymore. Its just simple to do it the same way GM did it.


O.K....my gears are turning, but perhaps they are turning backwards...
Now, if I have too little a vaccum signal to pull on the idle circuits on my secondary carbs, and the throttle plates are shut ( I mean TRULY shut ), then I am not adding fuel, nor am I adding air, at least until the plates open, so: Aren't they just sitting there dormant until my linkage reaches the point of opening the throttles on the secondaries?
I would not expect a rich idle, unless they are adding fuel.
If they are, aren't they responding to the vaccum, then?
I would also think that since vaccum signal decreases with the opening of the throttle, that until the secondary carbs are opening, nothing is being added in the way of air/fuel either, until the point of them opening via the linkage, and getting into the accelerator pump, No? Yes?
I'm missing something, huh?

DirtyThirty
02-10-2008, 10:15 PM
C'mon some carb guru straighten me out and make me look stupid!!!
lets go here, I know I'm missing something simple...
Why is it "WRONG"?

3x2rocket
02-11-2008, 09:51 PM
Dirty Thirty, you've already answered your own question. The secondaries are often called "slaves" or "dumpers".

At idle the primary carb does not feed gas though the venturi, it feeds on tiny holes (idle circuit) below the blades which are exposed to a tuneable amount of vacuum (idle mixture screws). When you open the throttle you engage the venturi (powered by vacuum) and the accelerator pump (mechanical) squirts extra gas directly into the body. If you floor it, you also engage the power circuit (opens at vacuum drop) adding additional fuel into the body through yet another set of holes.

The secondary carbs are inactive until they are exposed to manifold vacuum. Until the blades open there is no vacuum signal and therefore no gas being drawn through the venturi. When the secondary blades open the venturi feed gas via vacuum, you don't even need accelerator pumps or power circuits in most applications, in fact for street use keeping accelerator pumps often makes for too rich a mixture causing bad transition and bog. Racing applications sometimes idle all three carbs or a 4bbl with "four corner idle" does the same but this is only practical for a vehicle that will be run almost exclusively at peak power. A typical 4bbl carb has primaries and secondaries, only the primaries have idle circuits, then when you reach approximately 60% throttle they open, dumping more fuel/air just like a 3x2 setup does. The reason all three cannot idle is it would be too rich and it will take too much vacuum away from the primary carb resulting in poor air/fuel mixture and velocity at low rpms causing poor efficiency and performance.

It is true that a large, modern 4bbl with a good flowing intake manifold can out-perform a 3x2, but that does not mean 3x2s cannot be high-performance, dependable, and even economical. Its really quite simple, my rocket is a two barrel until I press the pedal more than about 60% to the floor, so if I drive casually I get mileage like a 2bbl, when I get aggressive I have 6bbl that works exactly like a mechanical 4bbl does. If you keep idle circuits in your secondaries you also need to have direct linkage making it a 6bbl all the time or all the different circuits of air/fuel in the carbs will not work right together.

DirtyThirty
02-11-2008, 10:37 PM
Dirty Thirty, you've already answered your own question. The secondaries are often called "slaves" or "dumpers".

At idle the primary carb does not feed gas though the venturi, it feeds on tiny holes (idle circuit) below the blades which are exposed to a tuneable amount of vacuum (idle mixture screws). When you open the throttle you engage the venturi (powered by vacuum) and the accelerator pump (mechanical) squirts extra gas directly into the body. If you floor it, you also engage the power circuit (opens at vacuum drop) adding additional fuel into the body through yet another set of holes.

The secondary carbs are inactive until they are exposed to manifold vacuum. Until the blades open there is no vacuum signal and therefore no gas being drawn through the venturi. When the secondary blades open the venturi feed gas via vacuum, you don't even need accelerator pumps or power circuits in most applications, in fact for street use keeping accelerator pumps often makes for too rich a mixture causing bad transition and bog. Racing applications sometimes idle all three carbs or a 4bbl with "four corner idle" does the same but this is only practical for a vehicle that will be run almost exclusively at peak power. A typical 4bbl carb has primaries and secondaries, only the primaries have idle circuits, then when you reach approximately 60% throttle they open, dumping more fuel/air just like a 3x2 setup does. The reason all three cannot idle is it would be too rich and it will take too much vacuum away from the primary carb resulting in poor air/fuel mixture and velocity at low rpms causing poor efficiency and performance.

It is true that a large, modern 4bbl with a good flowing intake manifold can out-perform a 3x2, but that does not mean 3x2s cannot be high-performance, dependable, and even economical. Its really quite simple, my rocket is a two barrel until I press the pedal more than about 60% to the floor, so if I drive casually I get mileage like a 2bbl, when I get aggressive I have 6bbl that works exactly like a mechanical 4bbl does. If you keep idle circuits in your secondaries you also need to have direct linkage making it a 6bbl all the time or all the different circuits of air/fuel in the carbs will not work right together.


O.K....to get past any further explanation on carb theory, which, I admit I do not know everything about, but, I am always grapplin'...let me get right out here with it:

I'm looking for straight-up science. Not ( and no offense to anyone, none at all...I'm just very inquisitive! ) quotes from books, or manuals.
somebody tell me why my tri-power set up works, AND works well I might add, with idle air bleeds.
It has a progressive linkage.
It idles at 500/600 rpm...
It is not overly rich.
The throttle plates on both secondary carbs shut fully.
The end carbs reach WOT at the exact same time as the center one.
It has excellent throttle response, both off-idle, and above, with or without a load.
It has functioning accelerator pumps...in fact, I removed the large spring ( the one that resists the onset of the pump plunger, to allow for more fuel, because the motor was stumbling when the throttle was cracked enough for the secondaries to come in ) since then, with the addition of more fuel when the secondaries open, it runs like a swiss watch. No lean stumble, just clean, quick rpm...
Why???
In fact...it runs G-R-E-A-T...I am to assume then, that it would run just a little bit better with no idle circuits in the secondaries???

p.s...
it is a reasonably mild motor, also, by my estimation...10.5:1, 228/234 duration hydraulic cam, 2.02 valve heads...no port work. Basic as it gets...

Tudor
02-11-2008, 10:45 PM
O.K....to get past any further explanation on carb theory, which, I admit I do not know everything about, but, I am always grapplin'...let me get right out here with it:

I'm looking for straight-up science. Not ( and no offense to anyone, none at all...I'm just very inquisitive! ) quotes from books, or manuals.
somebody tell me why my tri-power set up works, AND works well I might add, with idle air bleeds.
It has a progressive linkage.
It idles at 500/600 rpm...
It is not overly rich.
The throttle plates on both secondary carbs shut fully.
The end carbs reach WOT at the exact same time as the center one.
It has excellent throttle response, both off-idle, and above, with or without a load.
In fact...it runs G-R-E-A-T...I am to assume then, that it would run just a little bit better with no idle circuits in the secondaries???

If the secondary carb butterflies are "shut fully" at idle - they aren't leaking vacuum or contributing gas to the idle.
I assume the center carb plates are slightly open at idle if the engine idles.

You said it runs good. Exactly. What's the question?

DirtyThirty
02-11-2008, 10:52 PM
If the secondary carb butterflies are "shut fully" at idle - they aren't leaking vacuum or contributing gas to the idle.
I assume the center carb plates are slightly open at idle if the engine idles.

You said it runs good. Exactly. What's the question?

Thats what I'm thinking...thank you!
My question, though, really was: Why does everyone tell me ya' can't do it that way.:D

I'm also sorry to hi-jack...I would have started another thread, but, Root seemed to be doing a general investigation into the wonders of tri-power, so I figured I'd join in the knowledge hunt.

ZomBrian
02-11-2008, 11:54 PM
Not to hijack...but has or does anyone run the Offenhauser 3x2 with the larger base Rochesters? Their catalog says it's for generally "hotter" engines...but I don't know what is realistic.

saeger
02-12-2008, 02:17 AM
If you close the mixture screws all the way down in the secondarys will that eliminate the idle circuit thus allowing the use of unmodified carbs?

Tudor
02-12-2008, 06:26 AM
Thats what I'm thinking...thank you!
My question, though, really was: Why does everyone tell me ya' can't do it that way.:D

I'm also sorry to hi-jack...I would have started another thread, but, Root seemed to be doing a general investigation into the wonders of tri-power, so I figured I'd join in the knowledge hunt.

the key is the butterflies on the secondaries being shut or not. If they are shut sealed off and you leave the idle circuit in tact - they aren't doing anything when the butterflies are shut.

If you hae regular 2 barrels used as the end carbs witch cracked open butterflies, then you are idling on three carbs. Way too much air, gas, and not enough vacuum signal.

I am not sorry if anything was hijacked. Just kidding. :D

Abomination
02-12-2008, 09:24 AM
Yeah, man. If the outboard carbs are shut all the way, then they're sitting pretty much dead-to-the-world at idle. A carb that's not at least partially open is a brick, and the motor acts as if it isn't there. A carb won't atomize gas without the motor sucking air through it. Closed butterflies = no air OR fuel at idle.

A bunch of folks setting up 3x2s have problems sealing the end carbs. Some folks never figure out that this is their actual problem and give up after misguided jetting and fuel regulator and/or pump swapouts.

~Jason


Thats what I'm thinking...thank you!
My question, though, really was: Why does everyone tell me ya' can't do it that way.:D

I'm also sorry to hi-jack...I would have started another thread, but, Root seemed to be doing a general investigation into the wonders of tri-power, so I figured I'd join in the knowledge hunt.

Tudor
02-12-2008, 09:44 AM
If you close the mixture screws all the way down in the secondarys will that eliminate the idle circuit thus allowing the use of unmodified carbs?

nope because the butterflies will be open and leaking air/vacuum killing the idle fuel mixture the center carb is letting in.

Abomination
02-12-2008, 10:36 AM
Exactly.

You've got to kill both the fuel AND air in the outboard carbs at idle if you want it to idle at all.

That's why I was so impressed with the JB Weld thing above. You can pull the bleeder screws and epoxy the holes to cut off the fuel in the outboard carbs at idle, but the butterflies will still be open at idle, seeping air like sieves, throwing the idle mixture off. This just nullifies the great job that the unmodified center carb is trying to do idling the car (as you can imagine, with three carbs' worth of air at idle and only one carbs' worth of fuel).

The JB Weld thing is a way to make those end carbs seal really well at idle. And if they're sealed really well, they won't suck any air at idle. And if they're not sucking any air at idle, then you may as well leave the bleeder screws in and not mod the carbs any more - no air sucked in equals no fuel being sucked in either. Idle problem solved.

I had tried to solve it by thinning out the edges of the butterflies, surgically, and with a file - it takes a long time, but eventually it does work. I'll never do that again, thanks to JB Weld! :)

~Jason

nope because the butterflies will be open and leaking air/vacuum killing the idle fuel mixture the center carb is letting in.

DirtyThirty
02-12-2008, 02:52 PM
Exactly.

You've got to kill both the fuel AND air in the outboard carbs at idle if you want it to idle at all.

That's why I was so impressed with the JB Weld thing above. You can pull the bleeder screws and epoxy the holes to cut off the fuel in the outboard carbs at idle, but the butterflies will still be open at idle, seeping air like sieves, throwing the idle mixture off. This just nullifies the great job that the unmodified center carb is trying to do idling the car (as you can imagine, with three carbs' worth of air at idle and only one carbs' worth of fuel).

The JB Weld thing is a way to make those end carbs seal really well at idle. And if they're sealed really well, they won't suck any air at idle. And if they're not sucking any air at idle, then you may as well leave the bleeder screws in and not mod the carbs any more - no air sucked in equals no fuel being sucked in either. Idle problem solved.

I had tried to solve it by thinning out the edges of the butterflies, surgically, and with a file - it takes a long time, but eventually it does work. I'll never do that again, thanks to JB Weld! :)

~Jason


This is what I was driving at...exactly.
I was starting to feel like filling the idle orifice's on the end carbs was not exactly treating the actual problem, or at least kind of being a fail safe, which is fine too, in the event that the butterflies don't fully seal, but it seemed like it was hardly the only "right" way. I know if I put my hand over a running engines carb, and there is no place else for it to draw from, it dies.
The guy's with dual quads, they idle both carbs., and they have four corner idle circuits, in a lot of instances, due to the difficulty experienced with getting a motor to idle with runner configuration/cam profiles common to high rpm motors.

3Deuce40
02-12-2008, 03:00 PM
This is my first three deuce set-up and I can tell you right now, its also my last. They may look cool, but as far as reliability they suck. I'm sure mine need to be fixed or whatever, but I haven't found anybody yet that can tune these things correctly. I talked to Vintage Speed about a new set up for $1100 and they said "you'll still have to tune them". I'll be damned if I give them a $1100 and have the same problems I have now. Put a 4 barrell on it and away I go. The only problem is, I see tons of guys using them and they either don't have the problems I am having or they just lie and say everythings great.

DirtyThirty
02-12-2008, 03:09 PM
You'll always have to tune them, though, that should be expected, after all you have three carbs, that must work in harmony, and the manufacturer has no way of knowing everything about your specific combination, where you are, what time of year you run it, altitude, etc...
I, for one, will NEVER say I've had no problems with mine, it took a LONG time, all last year, in fact, to get them where I was truly happy with them. However, now I have no problems with them...I don't think I'm gonna fuck with 'em again unless they start being bitchy.
They quit at around 5500/5800 rpm, but, they STILL look bad-ass.

3x2rocket
02-12-2008, 07:10 PM
Not to hijack...but has or does anyone run the Offenhauser 3x2 with the larger base Rochesters? Their catalog says it's for generally "hotter" engines...but I don't know what is realistic.

Yep, thats what I'm running. Ran great when the rocket was stock, and even better now that its more cubes, bigger heads and cam. I posted a picture of it a few pages back.

3x2rocket
02-12-2008, 07:55 PM
Thats what I'm thinking...thank you!
My question, though, really was: Why does everyone tell me ya' can't do it that way.:D

I'm also sorry to hi-jack...I would have started another thread, but, Root seemed to be doing a general investigation into the wonders of tri-power, so I figured I'd join in the knowledge hunt.

Its never a matter of can't and always a matter of what works best for the application. As already stated if your secondaries are closed fully, (and sometimes they do seal pretty good with no mods) there is still only one carb idling regardless of circuits in the base because the blade will be closed above where the holes in the base are. By hte time they open your car is already at higher rpm so it matters very little if they bleed gas/air into the manifold.

As far as the accelerator pump thing, your car is far lighter than mine so a little richer will run well, whereas on a heavier car leaner is more desirable. Also you could possibly jet your secondaries bigger, lose the pumps and get a longer pull at WOT cause the venturi rely on vacuum to supply fuel and the pumps are done after the squirt, or even keep them and jet it larger maybe? I also wonder if yours runs so nice because it does get a little extra air from the open idle circuit to compensate for the added pump squirt? Of course if it works well, then don't fix it.

There are too many variables to have any concrete answers, car weight, cam, gearing, head flow, etc.

One fact is, 3x2 always looks cooler!

DirtyThirty
02-12-2008, 09:26 PM
Its never a matter of can't and always a matter of what works best for the application. As already stated if your secondaries are closed fully, (and sometimes they do seal pretty good with no mods) there is still only one carb idling regardless of circuits in the base because the blade will be closed above where the holes in the base are. By hte time they open your car is already at higher rpm so it matters very little if they bleed gas/air into the manifold.

As far as the accelerator pump thing, your car is far lighter than mine so a little richer will run well, whereas on a heavier car leaner is more desirable. Also you could possibly jet your secondaries bigger, lose the pumps and get a longer pull at WOT cause the venturi rely on vacuum to supply fuel and the pumps are done after the squirt, or even keep them and jet it larger maybe? I also wonder if yours runs so nice because it does get a little extra air from the open idle circuit to compensate for the added pump squirt? Of course if it works well, then don't fix it.

There are too many variables to have any concrete answers, car weight, cam, gearing, head flow, etc.

One fact is, 3x2 always looks cooler!


Ahhh!
You know, thats funny...BOTH of those things have been shambling around in my head, too...
I actually expected to have to jet it up, when setting it up, but, after my trick with acc. pumps, it roared, so...this set up was on a milder motor, prior to mine. I wonder, though, if I'd get more rpm out of it with jetting, though...hmmm...thanks for any and all input everyone...
I was actually thinking that, perhaps, there was something I was missing, and someone would simply lay it on me, and I would go rip my shit apart, do it right, and feel stupid!:D
Tri-power is fun.
And, I admit, the butterflies were not closing at first, either...it surged and idles all over the place, until I dressed them, and added a stout return spring on the linkage. I was just feeling around in the dark, and this is what I arrived at...

Abomination
02-13-2008, 09:00 AM
Man, you guys with 3x2 tuning probs need to take your car to a bike shop. No, not so much a Harley shop, but a Honda or Kawasaki or Yamaha shop. Not only can those guys tell you what to do to get those carbs tuned, but for a beer they can probably do it for you.

They usually run one carb per cylinder on the big bikes, and they sync them all the time with a vacuum gauge. It's not too big a stretch to explain how your linkage works and what you're trying to do for them to catch on and be able to help.

You may also want to shoot an email to Jere (pronounced "Jerry") Jobe:
http://www.vintagecarburetiontech.com/

He's the best Stromberg guy I know, but he's forgotten more about tri-power than most of us will ever know. He can also recommend a Rochester guy you can email back and forth with about tuning these. You know, like when you know all the notes on a piano, you can play any song.

~Jason



This is my first three deuce set-up and I can tell you right now, its also my last. They may look cool, but as far as reliability they suck. I'm sure mine need to be fixed or whatever, but I haven't found anybody yet that can tune these things correctly. I talked to Vintage Speed about a new set up for $1100 and they said "you'll still have to tune them". I'll be damned if I give them a $1100 and have the same problems I have now. Put a 4 barrell on it and away I go. The only problem is, I see tons of guys using them and they either don't have the problems I am having or they just lie and say everythings great.

Abomination
02-13-2008, 09:16 AM
Those dual quad guys sync their carbs with a vacuum gauge so they'll idle on both. They're set up to run that way - look at the intake runners, etc.

~Jason


This is what I was driving at...exactly.
I was starting to feel like filling the idle orifice's on the end carbs was not exactly treating the actual problem, or at least kind of being a fail safe, which is fine too, in the event that the butterflies don't fully seal, but it seemed like it was hardly the only "right" way. I know if I put my hand over a running engines carb, and there is no place else for it to draw from, it dies.
The guy's with dual quads, they idle both carbs., and they have four corner idle circuits, in a lot of instances, due to the difficulty experienced with getting a motor to idle with runner configuration/cam profiles common to high rpm motors.

murf-lostincity
10-25-2008, 05:31 PM
what size jets do i use for the end carbs on a 3x2 setup??


i am putting together a 3x2 setup offy intake 3 2gc carbs, 2 i will be modifying to work as dumpers from talking some people with experience doing the same thing

this will all go on 283 CHEV

Roothawg
12-07-2010, 10:00 PM
Back from the dead........good info in this thread.

cactus1
12-07-2010, 10:07 PM
I was just searching this stuff last weekend. More, more!

Roothawg
01-20-2011, 01:57 PM
Just an update. I bought a polished Edelbrock manifold and I guess I will try this on my own. I figure if I can rig a fuel control on a Boeing, I can figure this out.

alwaystiredlong
04-27-2011, 03:03 PM
Any rough idea of the jet sizes on the end carbs?

spark
05-04-2011, 04:23 AM
speedway says in tri-power instruction sheet- http://www.speedwaymotors.com/Rochester-TriPower-Base-Kit-with-Linkage,41655.html

#56 for primary and #55 secondary.

*this would be a small cube motor
..
.

Abomination
05-04-2011, 04:49 PM
Since we're back from the dead, here's a better trick than JB Weld: valve lapping compound. I've since put lapping compound on the butterflies and worked 'em until they sat flush. Works like a charm! ;)

~Jason

c-10 simplex
05-04-2011, 07:37 PM
Where to buy decently rebuilt 2Gs/Vs or C's?

spark
05-05-2011, 02:36 AM
do them your self its not that hard- have a look at this link (you have to sign up to see the pics but its worth it)- http://www.v8buick.com/showthread.php?t=86177.

Since we're back from the dead, here's a better trick than JB Weld: valve lapping compound. I've since put lapping compound on the butterflies and worked 'em until they sat flush. Works like a charm!

~Jason

I will try this myself and also use the throttle blade sealer (DAG) from this site- www.pontiactripower.com - they also have rebuild kits and parts.

..
.

fryguy
07-12-2011, 11:30 PM
What cam grind are you are you guys running on the SBC tripower setups?


Fryguy