I've done a search and came up with most of the information concerning the desired fuel pressure for a SBC tri-power using Rochester 2G carbs. I intend to use a Holley low pressure 4 pound regulator. I've read where some were experiencing problems trying to adjust the pressure and the regulator would not drop the pressure to the desired level. It was suggested that the high output pressure of some fuel pumps would overwhelm the regulator 4 pound spring causing the fuel pressure to be above the limit of the regulator. Is this feasible? I am running a stock Chevy mechanical pump which is supposed to put out 5-7 pounds pressure. I want to install both a fuel filter and regulator in the line between the pump and the fuel log and set the pressure at the maximum 4 pound rating. I intend to mount the regulator inline in front of and just below the right cylinder head so it will not be quite so obvious. I'm hopng that this location will not create too much heat causing vapor lock problems. It's my opinion that the regulator can be mounted in any position with the outlets either vertical or horizontal. I want to mount it however it best fits my application. What's your thoughts and experiences with the SBC tri-power fuel pressures?
I run a stock Carter fuel pump with about 7lbs, no regulator. Run a good inline fuel filter and let her eat.
run a regulator by all means! i ran that setup a few years ago in a SBC and she would surge like crazy at idle,it did exactly that,had a carter fuel pump running 7psi and was overcoming the regulator spring switched to a different regulator from NOS and it maintained fuel pressure surging went away.The pump was filling the bowls so quick it was overcoming the floats and spilling over in the 2G's.Are you running a progressive linkage?no choke provisions on the outer carbs?(dump carbs)?you can mount the regulator in any position,doesn't matter but keep away from direct heat(next to block) otherwise vapor lock will happen...
I've never needed one running a stock mechanical pump or an electric replacement pump with Rochesters. I've never run any highfalutten race car pumps though, just the garden variety electric pumps for carbed engines.
Chevy specs. are 4 1/2 psi for their 3 carb. 2GC setup, any more pushes the float needles off their seats. Thats all I run on my Caddy 3 duce setup. Take this as fact I was a factory trained master technician.
Here is a pic of mine, I have been running this set up for several years. You can see the regulator just in front of the block deck, its shiny with a touch of orange silicone to keep the knob from rattling. I have to run it or the stock pump overcomes the needle and seats and it will flood. I also run mine with only 2 pounds of pressure. I believe the reason for this is my stock model A tank has a pretty good head pressure when it arrives at the pump. Never any problems with vapor lock but I am running hoodless so no built up heat involved.
If you use fuel valves in the carburetors with the correct orifices; a regulator is not necessary with a stock fuel pump. Many aftermarket rebuilding kits have much too large an orifice in the fuel valve. Jon.
You can see in the pics that I'm routing the fuel line back from the pump up to the filter on the firewall, then down along the area between the valve cover and intake to the "low pressure" regulator. Never had an issue with vapor lock or anything yet and its seen plenty of extended highway driving. One thing I don't like, and this may be because of the restrictiveness of the regulator, is that when under full throttle it will "run out of gas" by draining the carbs faster than the regulator can pass fuel on to all three carbs. I could barely complete a full 1/4 mile pass with this setup. Probably need a seperate regulator for each carb to solve the problem?
I ran a pressure regulator on mine and dumped it. It ran fine if I was going 25 to 30 mph. Then it wouldnt fill the bowl fast enough and would die. canned the regulator and been running like a raped ape ever since. Progressive linkage, holley electric pump (10 psi) and an inline filter. Just really make sure that the dumpers seal other wise it runs horrible. Invest either in the base kit set from speedway or at least buy the brass (thicker, and steeper angle) to seal the end carbs off. I allso found that vacum advance made it Idle weird so I ditched that too. 36 degrees....... lovin it, but hate the gas milage.
It's volume not so much pressure to keep the carbs full. The use of a 3/8" feed line from your tank will solve most starving problems. Engines with 3-2's run on a single carb for 99.99% of the time unless your a "happy" throttle guy and a stock pump at 4psi is plenty. My dual quads run with 4 and I can open them up on the freeway and not run out of fuel. Good luck.
I'm running the exact setup you describe. Running 3lbs. I've never had any issues. The thing runs like a dream
Shop: Charlie Price's Vintage Speed sells 4GC bases which do not have the idle adjustments and longer right side throttle shafts. He is in Florida. Good products and he's pretty proud of them. I bought some linkage from him and it was nice stuff that worked.
Jimmy- I have looked at his parts and Speedway-just trying to avoid the 3 bill price tag and besides, I like to say "I did it myself"Funny thing is I bought the manifold , 3 carbs, 3 chrome filters and linkage in a cardboard box for $65 on C/L. Thanks for your post.
Yes, Get a good modification kit and change the base plates and butterflies so that they seal and only work as dumpers. The kit with all linkage and the fuel bock and lines is about $400 and well worth it. If you look close, you can see that all of the old screw holes are plugged and capped. I run 5-6 1/2 psi on mine and it does just fine without any regulator. The 2GC and 2G carbs were made to run that pressure. My tank is in the rear and just a bit above the engine.
I've run several sets, after a long battle on the first set I used a regulator set it at 4psi, I used the same on the other 2 units with great results. Your results may vary.
I have tri power setups on a sbc in my '40' Ford and my '55' chevy. I use a regulator on both with pressure set between 3 and 4 pounds. Both run and idle great with progressive linkage.
I'm having some issues with my 40 I’m having some issues with my 40 Ford running Rochester 2g setup. It always ran a little rich and I couldn’t do parades because it would backup. I’ve added AC and some other things now of it is too warm out(everyday in Tennessee) I’m not even able to enjoy my AC because my temps are getting to hot. My fuel is boiling if I have to drive someplace slow like in a park or I have to sit too long at a light (everyday in Tennessee) my heat rises and about 190-195 it has a hard time running. The fuel starts backing up and flooding. 195 isn’t really even close to hot but my fuel isn’t liking it in the slightest bit. I had put on a tri-power single helmet air cleaner and went back to my frog face air cleaners, I installed Phenalic Risers from Dashman. When I installed the AC I also installed the proper parts that go around the radiator and the pan under it that I never had before to direct all of the air directly into the radiator. I have a Walker radiator but was told to go to an aluminum radiator because it will run cooler. I have a regulator I’m getting ready to install but I’m trying to find a place to install it at and where to run the lines as in before or after the pump. The new fuel pump I put in says I’m running 7psi and from reading that is about double of what I should be running. I don’t know if the gauge is right or not but I’m sure I will see when I put in the regulator because it has a gauge as well. It’s strange I never had this problem in the last 4 years other than parades and such. Where is the best place to run the regulator after the fuel pump or before it? I am going to run it deadhead
Regulator goes between the fuel pump and carbs. I have a Holley 1-4 psi regulator on my Rochester tri-power setup. It’s fine, but the gauge always seems to be 5-6 psi no matter the regulator adjustment. Might be the gauge…. runs fine though. I have a Holley Red pump pushing fuel from the tank and no mechanical pump. John
I had the big base GC's on my setup. Ran 'em both with the stock pump and a regulator. They did o.k. for a while with the stock pump, then I had problems with flooding, even after rebuilds, etc. Put in a regulator and still had the problems-then I checked the regulator and found at a 4psi setting it actually put out about 5-51/2. Finally settled on a 3 psi corrected output, end of story.
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