Technical What carb for tunnel ram

going to be acquiring a weind tunnel ram (the one with the smaller top for less plenum volume) single carb top.

Wanted to know what's the best carb to use between a holley 650 double pump or a new summit/holley hybrid with annular boosters and vacuum secondaries.or even a 650 holley with vacuum secondaries(cheapest of the options)

In a light car,very mild 350 with a 480lift cam,headers and 3000 stall converter. I know double pump is usually the way to go but wanted to ask first.i do know my pop has the summit carb on a 302 and it seems to never need any tinkering. But it's not a t ram

 

btt

 

Via the search button:

http://www.jalopyjournal.com/forum/threads/tunnel-ram-carb-sizing-question.48904/
http://www.jalopyjournal.com/forum/threads/tunnel-ram-carb-theory.302635/
http://www.jalopyjournal.com/forum/threads/tunnel-ram-carbs-450s-or-600s.743034/
http://www.jalopyjournal.com/forum/threads/350-tunnel-ram-questions.405600/
http://www.jalopyjournal.com/forum/threads/single-carb-tunnel-ram-setup-help.676529/
http://www.jalopyjournal.com/forum/threads/tunnel-rams-on-the-street-whos-run-em.137389/
http://www.jalopyjournal.com/forum/threads/single-4-tunnel-ram.428241/

And so on...

 

Hey x38, via the sorta rude comment,ain't most of those about dual carbs? I was asking between the carbs I listed...

There is a little bit on single tops,I've read them. That's why I listed the double pumper because it's 4 corner idle circuit

 

If I was trying to be rude, I would not have put the effort in to search and post links.

 

Any luck from the weekend crowd? Thinking about the holley dp,something about the 4 corner idle that seems like it would be a good way to go

 

I would look for a 750 dp.

 

On such a mild engine? Low compression 350 with headers,comp cam and high stall converter. Stock heads

 

I built a tunnel ram in 1964 and used two AFB's. It was two much carb and went to one carb. I ended up with a single quadrajet. The engine was 360 hp 327 with a Isky cam. A tunnel ram moves the air smoothly because of the plenum and does not need as big of carb as a traditional manifold.

 

I run 2 x 550's two barrel's . My combo need's 1,075 cfm's mounted side saddle.
Put 2x 300 or 350's Two barrel's .
2 x of any thing biger then 650-750 cfm's ""total cfm """ on yr combo is just a waste of $$

 

A 750 should fill the intake nice with air/ fuel and make for easy tuning and a power house.

 

Years ago I had an Edelbrock TR1-Y with a single top. I put it on an internally stock "real" 300 horse 327 with a mild port and polish job and headers. I tried a Holley 600 double pumper and it didn't run worth a crap. Bogged off the line, had to fiddle with the floats and jets and once it would run great, there would be a change in the outside temp and it would throw everything out of whack, again... I switched to a 625 Carter Competition series carb and it was like night and day. Literally woke that thing up. I know the Competition series aren't made anymore but I am pretty sure there is an Edelbrock equivalent??

 

I don't have any experience running a single 4 barrel on a tunnel ram personally,but all the guys I've talked to at local shows or cruise nights who try to do it with a small carb on a stock-ish mild cam/low compression build seem to come away disappointed.
If you're going to run a single carb,you're better off to run a single or dual plane intake like Victor jr or a Performer RPM.
If you really like the tunnel ram idea,give it a chance to work,and give it a decent port job,a pretty serious cam,and a pair of dedicated tunnel ram carbs built by a reputable carb guy.
If you tie on hand behind your back by not giving that tunnel ram the other parts of the equation that it needs to work,you're sure to be disappointed.

And regarding carb sizing,do NOT go with 450's if you run two carbs.You will never get them to work right for you.
Get some recommendations from carb guys and compare what they say.You may be surprised.

I know my motor is a little more ridiculous than what you're looking at building,but it's an example of how unconventional tunnel ram carb sizing really is compared to coventional style intake carb requirements.
My 368" small block Ford runs a Weiand model #1988 tunnel ram,good heads,a pretty gnarly solid roller cam,a fair bit of compression,and two Holley list # 6109 carbs.Thats two 750s for a total of 1500cfm on a 370" motor.
And the torque is strong through the lower midrange.As soon as it gets up on the cam it's really grunting out the torque. Like over 400ft/lbs when we started the pull at 4000rpms.Maxed out at 492lbs & 5500rpm.

Scott


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Powersftr-I think uh...

I'm not going to 2 carbs,a single can be done. And I'm going with the ram,I have tried all sorts of intakes,I'm aware a dual plane is supposed to be the best for the street.im not using one.i also stated I already have a pretty alright cam in it and high stall.this isn't my race car,I have a 383 for that. Can't afford to hop this old 350 up right now anymore than it is

I already run tri-powe and am taking it off



Also posted above about the carter competition series/edelbrock. That's not in my list. I've had 3-4 of those and hated them all. I'm convinced edelbrock can not make a carb.

 

I really just want to know vacuum or mechanical secondaries!

 

Carb's are not just a bolt on!!! There is more then mixture screw ,power vale & jet's ,
Most just want a bolt on & go , Not put the time into Tuning carbs , think they are fast by seat of there pants, Disappointed when they put it on the Clock .
Are you trying to make power, or run ok or the look of twins on a tunnel ram .
Most tunnel ram's work from 4,000 rpms up .
Its not hard to figure out the CFMS needed ,
On my set up I have several hours ( 40) or so to WORK correct, threw all RPMS
cruse to wide open . Two 550s 2 barrels. I drive this car daily, all steel No cage ,No street slick's ,Plain jain Bridgestone 7 inch wide ,short shift by 2,000 rpm's . SBC runs 6:60s in 1/8 @ 103 mph
Strip or street

 

Its all depends on how you want yr combo to work ,& what you are trying to accomplish .

 

Hombre on here has been running a tunnel with a single carb on a 350. He has been driving all over, and say' it runs great for him on highway or street. I will be running a tunnel also.

Pat

 

I agree with this heavily.Squirter sizes and pump cams,high speed air bleeds,stuff that the average guy may not have a handle on,will probably be required to get it to run hard up top and pull down low too.
A call to a really good custom carb supplier will be money well spent.And putting some time in to get things really dialed in will be a given.
What 19Eddy30 said about carb sizing seems to fit pretty much exactly with my personal experience as well.Most guys would think 1100 cfm is waaaaay too much for a 350,but it's just not the case with a tunnel ram.They're a very different animal.
Once it's dialed in correctly,expect a truckload of torque from those long runners,though!If you put the time in,you will definitely be rewarded for it.

Scott


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Okay.. so witch carb do I get to start with?!? Dear lord you guys


Also this ram is supposedly 2400 rpm and up. Not 4000...

 

I ran two Holley 650 DPs on a ram, 355 SBC years back. As 19Eddy30 stated, lots of tuning and some carb mods to get it working correctly on the street. You better have a good amount of compression , stock comp. does not cut it for a tunnel ram IMO.

 

Tunnel rams have a lot of volume to them. IMO, the extra pump shot for the secondaries and the pump cam choices for primaries also would make the DP where to start. 350 Chev with a mild cam and a stall to keep 'er revved up. 650 cfm could be all the engine can use. Pretty sure any larger than that and the venturi's get bigger, too.
Many T buckets had single top TR intakes in the 70's.

 

@ 2,400 rpms !!! is it a Tunnel ram or two four intake ,what Brand & #?
There is Cfm Calculator s,
You can run a single carb ,
When you go to tune ,install a Wide band O2 ,it will make your life easier ,Tack a big Vac gauge ( my Vac gauge is 5 - 6 inch that reads in 1/8 increments ) I use for tunning ,
,BUT plain to take carb or carb's apart more then 3 or 4 times. with lots of notes !!
If I was to run single cab or a tunnel ram ,I would run a Double pumper !

 

I would run a carb that has the secondaries open on airflow demand. It could be by vacumn or a flapper like an AFB. The problem is to get enough fuel mixed with the air so it does not bog. Avoid opening the secondaries too fast. Have them open when needed.

 

Of you just have to use the tunnel ram, use the 650dp. But the better choice is to use a regular dual plane like an Edelbrock Performer with the mild cam and low compression.

 

If your biggest worry is vacuum secondaries vs mechanical,I think you're going to have a long road ahead of you to get this thing to run decent.

Lots of these guys are trying to steer you toward a slightly different approach because they have been down this road with poor results.

With stock heads,a big intake,and a small carb,it's going to be pretty soft.
Those t-buckets from the 70's that were mentioned earlier,got by because the whole car weighed about 1500 lbs.
A Briggs & Stratton could move a car that light.Is that what this motor is destined for?If so,you may be able to get by with it.
Even if you were able to bring the compression up a touch...maybe run a 1.6 ratio rocker on the intake side to help it fill the cylinders,and do a bit of a home porting job,I think it would be a big step in the right direction toward getting the whole thing to work better for you.
As is,with stock heads that don't make any compression or much in the way of airflow,a small carb,combined with an intake that wants lots of airflow,compression,and carburetion,I don't think you're going to be very happy.

At the very least,consider a 750 as Saltflats has suggested.And don't forget to get the distributor working right,too.A lazy,stock smogger style ignition curve will make that motor run like a dog,but light springs and a quick advance will go a long way toward helping it feel a lot more crisp.

Scott


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Scott has pretty much said it all. Good advise for the OP.

 

A tunnel ram on a motor not designed for it, will be less than impressive in performance. Be prepared to be disappointed.

 

I tunnel ram on the street will never "act" as you want it to . Just is not designed for normal drivability . No heat to carb , no vacuum , as pressure drops across throttle plates it has a cooling effect anyway , just a 100x worse with a tunnel ram . You may get to to act perfect , wait 3 days till weather change , start all over again .


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