Problems with offenhauser/holley setup
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Joined: Jan 2001
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Problems with offenhauser/holley setup
Hi everyone, well i finally went all out and put the offenhauser intake and holley 390 on my truck, along with headers. Problem is, it has run awfully ever since. Symptoms: at idle, in park the engine races, probably 2000-2500rpm, but in drive it stalls. When starting to go, it is very tricky...too much gas and it will cut out, or make a real loud pop, then keep running when i let off the gas. If i use the throttle very gradually, it will do alright, but it still doesn't pull the way it used to. I'm pretty sure that it's burning really rich...but i don't know what i can do about it. I just replaced the power valve, but it didn't help much. Should the timing change with the new setup? It was running fine before the install....I don't know what else to do.
Thanks everyone for your help, Dennis
Thanks everyone for your help, Dennis
Junior User
Joined: Aug 2000
Posts: 73
Likes: 0
Problems with offenhauser/holley setup
Hard to tell what is going on exactly until you get the idle down to approx 800 rpm and smooth but here are some guesses/things to think about.
Idle too high:
1) high idle cam for the choke is stuck on - is it electric?
2) idle screw adjusted too high
3) plates on the bottom of the carb binding on the gasket/manifold and not allowing them to close
4) vac leak around manifold/head/carb
5) vac advance connected to wrong spot on carb
Once you get the idle down to approx 800 rpm you will have to adjust the air/fuel mixture - I expect you are planning to already!
Do I understand that you have a bog off the line when giving it gas? If so you have the same problem I had - had to feather the gas to keep it from bucking then it would take off.
I tried larger shooters and different accel pump cams and had no luck. Put on the 50cc accel pump kit and problem gone.
Best is to get the idle adjusted and then decide on the 50cc accel pump.
Idle too high:
1) high idle cam for the choke is stuck on - is it electric?
2) idle screw adjusted too high
3) plates on the bottom of the carb binding on the gasket/manifold and not allowing them to close
4) vac leak around manifold/head/carb
5) vac advance connected to wrong spot on carb
Once you get the idle down to approx 800 rpm you will have to adjust the air/fuel mixture - I expect you are planning to already!
Do I understand that you have a bog off the line when giving it gas? If so you have the same problem I had - had to feather the gas to keep it from bucking then it would take off.
I tried larger shooters and different accel pump cams and had no luck. Put on the 50cc accel pump kit and problem gone.
Best is to get the idle adjusted and then decide on the 50cc accel pump.
