Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Idle problem
Pat:
No. The cap is just a pressure relief device and provides access to the coolant circuit. It is designed to keep a certain pressure thereby raising coolant boiling point.
You've got a head scratcher, man. I am sure you'll figure it out.
dlphil10:
Would it idle a bit more rough if the compression is lower like observed. Should I go for a cam that closes the intake valve sooner in the cycle?
Cliff Ruggles:
120 psi is really low for cranking pressure. Did you degree the cam when it was installed?
That cam should make a lot more cylinder pressure in a 350 engine with 72cc heads on it......Cliff
dlphil10:
I originally had bad 46 heads on the motor when it had the comp cam factory muscle and I fixed the 061 heads as a replacement. The mistake I made was not CCing the heads. However, even as the 041 cam went and wiped a single lobe, the same head combo had at most 150psi cranking pressure. Thats what is weird.
The current 60240 cam was installed and degreed at 110 degrees. Do you think 2 degrees off (ICL of 108) will make a large difference in cranking pressure?
I did find my throttle cable was not fully extended as I was using a different year intake/throttle cable setup. It was keeping me from full throtle by about 3/4-1" so I am wondering if rings are not seated. I have verified that cross hatching is still present on the cylinder walls and that the cam is in good shape.
Thoughts? I sure do appreciate it.
Cliff Ruggles:
120 psi cranking pressure is pretty "low" for a N/A V-8 engine. It indicates low static compression combined with late cam timing or cam too big for the application.
We like to see at least 150psi cranking pressure for these engines, most of the ones we build here are around 170-180psi.....Cliff
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version