Tri power rochester end carbs once and for all

This isn't entirely correct.

The float settings are listed per carburetor number. The major sort is the make of car, as often carburetor tags are removed, thus the number is not known, and you have to guess.

The key here for adjustment is not what engine, but what carburetor. Hopefully, the carburetors have been sized to the engine. Figure out what EXACTLY the carburetors were originally used on, and adjust the floats accordingly.

Jon.

 

thanks for all your help. Followed all the tips. Its running really well off the center carb now, although the choke has to be about 1/4 open. Have to make fuel lines to run the secondaries. Doing that tonight
http://4hate0.net/tripower.mpeg

 

Let me be the first to recommend that you disconnect the linkage at the accelerator pump at the front and rear carbs. Drive the car and note how it runs. This is the advice I received from Charlie Price. I did this, and my tri-power works great.

Think of tri-power as a normal carburetor with primary and secondary venturies. If your pump is working properly, one will deliver plenty of fuel to prevent a lean (bog) condition. If you are still running the old leather type of pump get rid of it and get one of the newer ones that Charlie sells. Also, look into replacing the power valve with one that Charlie sells. This will even out the off idel acceleration performance of your tri-power set up.

5 psi fuel pressure is also good advice, as mentioned by someone else in this thread. Install a pressure regulator and a guage. Once you have the set up done correctly, you will love it, as I do mine. These are really simple carbs and quite reliable.

I run .056 jet in my center carb and .055 in the others. (350 chev with a mild cam in a 49 chopped merc)

Just a short note on the vacuum issue; True ported vacuum is a result of the "smog motor era" thats why you won't find it on a 2G carb. An engine will run cleaner at idel if the timing is retarded. There is no vacuum at idel but as soon as you crack the throttle open it acts 100% the same as a manifold vacuum port. Unless you have an emission control issue, don't hook your vacuum advance hose to port vacuum. Your engine will run cooler and idel smoother with manifold vacuum.

In general, with a stock or mild v-8 you want 12-14 deg initial timing, 24-26 deg mechanical advance, which will yield 36-38 deg of total advance. Then you want 16-18 deg of vacuum advance at cruising speed. This will yield 52-54 deg of advance. I've used this set up on all of my cars with easy starting and good performance. Make sure you are "all in" with your mechanical advance at your cruising rpm. (2300 rpm at 70 mph in my case) YMMV

 

Thanks for the tips Ruby. Im still ironing out the bogging. gets better with every little step. I left the acc pumps connected - Ill disconnect the links and try. I left the stock jets in, going to replace those as well. Do you, by any chance, know if I should run a Vent tube on my primary carb, or all the carbs for that matter? I dont have one on my center and was wondering if this would be an issue. Thanks again!

 

[ Do you, by any chance, know if I should run a Vent tube on my primary carb, or all the carbs for that matter? I dont have one on my center and was wondering if this would be an issue. Thanks again![/QUOTE]

Sorry I don't know.

 

Any carburetor MUST have a bowl vent in order to function. Many of the Rochesters have a vent into the air inlet, but no actual tube; this is OK.

Failure to connect the accelerator pumps on the secondary carbs will normally result in a MASSIVE HESITATION unless the primary carb is calibrated WAY too rich. In fact, the most common complaint we hear concerning tripower is failure of the modern neopreme accelerator pumps with ethanol fuel. Once the carbs get leather pumps, this issue generally goes away. The factory units used accelerator pumps in their "dumper" carbs for a good reason.

Jon.

 

So I shouldnt disconnect the pump linkages? . I dont have a vent tube sticking out of the primary carb, but it does run.

Do you know if I need the idle vent valves? My primary has a plug in it , but the secondaries have the valves. Seems to me it should be the opposite

 

Biggest problem you'll face is the vacuum leaks. ALL the bases on the end carbs, stock, leak. Don't believe me-just spray some carb cleaner in the end carbs, one at a time, and hear the motor rev. I've got the big base Rochesters on my 327 Chevy, true Pontiac end carbs, with the vintage speed aluminum bases and brass butterflys--they don't leak. BTW, they all use acc. pumps, like the factory. You should block off the two end carbs, get the center one running great, then put on the others one at a time--you'll find your problems.
cooger

 

Frank Oddo did a great story on how to set up 2gc's in Street Rodder i cant remember the issue but i'm sure someone here will, i followed the article to the letter how to turn standard carbs into secondary carbs (blocking off power valves ect ect )18 years ago and my Windsor is still running fine (although i've been through 12 rebuild kits) cheers oggie

 

Jon I am so glad to hear your comment about the issue with the neopreme pumps and modern gas. I just rebuilt a set of carbs and had hell with the accelerator pumps. It appears that the neopreme swells and causes the pump to seal on the upstroke which causes it to almost turn inside out. I finally fixed mine by taking a small tri cornered file and cutting a few small notches in the upper ridge of the neopreme to keep it from sealing against the carb body on the up stroke. Seemed to do the job. I have another set to rebuild for a buddy in the near future and we already purchased the kits. Do you sell the leather pumps by themselves or know where I can get them?

 

I would ask Larry @ Hotrodcarbs.com / Automotion in Montana. This guy is the world expert on Rochester Tri Power.

 

Anybody have a link to anywhere that has an ID guide for the 2 barrels? I have collected several & would like to figure out what they are from before I decide which ones to use. Hope to find a matching pair to convert to the outer ones.

Did GM make any/many different CFM 2 barrels like they did with the quadrajet?

 

Google the carb numbers to find original application. You can ballpark cfm's by physically measuring them and comparing them to this chart.
From Rochester Carbs by Doug Roe:

 

I am finding vaccum leaks to be tricky - Getting there though. Im glad to hear the info about the neoprene pumps, I would have never known

 

All most there. Do I need a vacuum line from the base of the carb to the back of the Manifold?(pictured). this is causing most of my leaks. I sealed it off and it sounded and idled allot better. Havent tested under load though. When plugged I still get vacuum to distrib and Tranny. and it runs with the choke open when plugged.Thanks again

 

I'm not familiar with the 390 fords but If that connection on the back of the manifold goes to the valley area then you need a pcv valve in the hose between the carb and the manifold. I'd plug it off untill you get the carbs lined out. Also check for vacuum leaks up by the air horn where the choke housing would attach. If any of these carbs had choke thermostat mounted up on the carb then one of the holes will be ported straight to manifold vacuum. They can be plugged by tapping with a 1/4" tap and screwing a allen set screw into it.

 

Yes that is the PCV connection.



This is the one that I use. I also packed the fitting in the back of the intake with a copper pot scrubber that I got from the grocery store to act as an oil baffle to prevent it from sucking oil spray. I believe that Ford had some kind of metal baffle mounted to the underside of the intake on these year FEs. I didn't have one so I did my own thing.

That vacuum leak doesn't have anything to do with the 3-2s. It will always be a controlled vacuum leak but you will adjust the carb to allow for it just like every other car with a PCV system.

 

Sweet - Thanks guys. I was thinking last night- how can it be pulling vaccum through the carb and the manifold at the same time? Seems like they would be fighting each other. Didnt think a 66 390 would need a PCV. That Mercury Engine is a beauty BTW

 

All engines need some type of forced ventilation to prevent sludge build up. That intake was made right about the time that the factories were going from a road draft tube to the PCV system. (1964-ish) I'm pretty sure that there was a road draft tube that will fit that intake if it was used on the earlier FEs but the PCV system is a better system. That hole in the back is under the intake runners and open to the lifter gallery. I had to pay too much for the fitting in the back of the intake but it was what I wanted and I just assumed the position.

66 FEs had the PCV valve in the pass side valve cover. My engine above is a 66 352 that came in a truck. I'm just using the earlier valve covers so a new PCV valve location is needed.

Thanks for the compliment.

 

My manifold is an edelbrock f380. It has a pan bolted across the bottom. I assume that is to block the oil. I just got an inline PCV that I can splice into the hose. That should work , right?


found the answer at the bottom of this page

http://www.squarebirds.org/pcv_conversion.htm

 

Just make sure that you install it so that it flows from the intake toward the carb. I always blow through mine just as I'm putting it in place to make sure.

The one in their picture looks like the hose is a different size on each end? The one in my picture above has threads that screw into the Rochester base with a 3/8" pipe elbow to clear the rear carb. The hose goes from it to the intake fitting.

My Edelbrock intake was NOS and had never been mounted. I did not have an early intake to harvest the plate from. You should be fine.

 

Thanks Tommy. I never would have thought thinking about installing a PCV valve would make the work clock click so slow. Been working on the engine all day in my head ;-D. 3 hours to go.... grrrrrrrrr!!!

Saw you are in Maryland. I was born and raised In Frederick. All of my family is still there. As a matter of Fact Mom and Pop are spending the week in Ocean City. I miss it.

 

Hooked up the PCV - Idles great- can run without choke. It gags(hesitates)when I crack the throttle with the choke open. Im only running the center carb. Ive triple checked the secondaries and there are no leaks and the fuel lines are disconnected

 

Did you let it warm up to operating temperature? Once it starts you can back off a little on the choke until it warms up but a little choke will make it run better until it's up to temp.

Is the accelerator pump pumping fuel?

It sounds like you are close.

 

I didnt let it warm up to op temp. Didnt even think about it. thanks for the tip..again.. I am getting close. Ill post a vid burning off the tires when I get it all sorted out ;-D

 

If you've never driven a car with a manual choke...You will have to get used to what the car likes. Pull it on until it starts and then push it back in slightly as it warms up. It will start to stumble if the choke is too far out for your conditions. Once it gets up to temp you then push it all the way in. It shouldn't take much in Arizona. You will have to get the feel of it. The thing that I like about a manual choke is that the driver controls it. You can get electric heated chokes for the Rochester's but in this part of the country it can be hard to get it adjusted so that it works well in July and January.

I thought that I would have the only FE 3 Deuce carb system with a manual choke. My 56 came with a 6 cyl and had the hand choke already in the dash. It now works the Rochester carb.

 

My 58 was a 6 with a manual choke. Trying to find an original cable and knob to fill the choke hole that stares at me.

 

Getting better everyday. Finally got all 3 hooked up progressive . Idles great and runs great, Thanks to all of your input. Couldnt have done it with out your experiences. It stumbles if I crack the throttle from a stand still but is fine if I ease into it. I think I need to change the Jets. I left the stock ones in. Have no idea what size they are

 

Any Suggestions for Jet Sizes? Its a 390 bored .060. I bought a set of 55 for outside an 56 for primary. I havent tried them yet but they seem kind of small. thanks again for all your input

 

if it stumbles when you crack the throttle but ok when you ease into it, jwould look at the acell pump ckt first, it may be lean