1972 chevy c30

[jbh7052]

well I think I found the problem. I bought a summit racing fuel pressure gauge......it reads 11psi!!! not sure how accurate the gauge is because I have never had a fuel pressure gauge before. I am running a new AC Delco stock fuel pump. so is it better to install a regulator or invest in a different pump?

[Cliff Ruggles]

11 PSI is pretty high for any carburetor.  The later fuel pumps used higher pressure and often you'll see very float settings for certain carburetor numbers.  I prefer to get the fuel pressure down to around 6-7 psi vs running the float nearly on the bottom of the bowl......Cliff

[jbh7052]

got the fuel pressure down to around 4.5. I used a summit fuel pressure gauge and regulator. Regulator adjusts from 4.5 to 9.5 and i adjusted it all the way down. However, still have hot start problem after it has sat for 20 minutes or so. The gauge will actually rise roughly a pound after turning the engine off and it sits for a few minutes. After a couple minutes the pressure will drop to zero fairly quick. New clear fuel filter installed just before the regulator and obvious the pump is allowing the fuel to drain back to the tank because the filter is almost empty. i know that has nothing to do with the issue i have but just stating things i observed. Guess next step would be to remove the air horn and set the float a little lower??? Maybe pressure check the bottom plugs like i should have during the rebuild!!  
   

[Cliff Ruggles]

4.5 psi is a little low, I'd set it at 5.5 to 6 psi as fuel pressure does effect the level of fuel in the bowl during operation.

Pressure check the bottom plugs, sounds like you are getting a leak into the intake after shut-down if it acts flooded/difficult to start after 20-30 minutes of sitting......Cliff

[jbh7052]

pressure checked the plugs and did have a small leak. Didn't seem to be to bad but the carb was not hot like it would be after operation. drilled, taped plugged and epoxied and had to order a choke pull off. as soon as i get that from your team i will give it a good try again. thanks so much!!

[jbh7052]

Got the choke pull off installed. Drill tap and marine tex the threads fixed the hot start! However, during the process something changed! I now have a stumble at steady throttle. The only thing I changed while in the carb for the main well plug leak was to change the plastic retainer that hold the power piston in place. I had left the original in when I rebuilt it but since I was there I decided to go ahead and put the new one in. It was super hard to get in place. The power piston moves up and down freely by using my finger but would that cause the stumble of it was not moving easily? Again it didn't do this before I replaced the choke pull off and the small plastic retainer  on the power piston.

[Cliff Ruggles]

Check the power piston hanger arms, make sure they are exactly level and even.  Most likely the hanger is bent down on one or both sides, see this all the time......Cliff