Does anybody have any idea what kind of fuel pressure an LT1 should hold at idle?? I ask because I have built a 350 to replace my 305 and the new motor has got a cam a little bit more radical than the LT1. I know its going to run lean anyhow because the computer is not tuned but i have an adjustable fuel pressure regulator and would like to at least try and get it to not run too lean..

 

Hi
I assume you are talking about a LT-1 (mid 90s) - I believe this is correct:You should be around 38 psi at idle, sitting in your driveway. Then disconnect the vacuum hose from the FPR. Your pressure should go up around 4 psi, simulating WOT.
thanks
Bill

 

Fuel pressure...36/38 PSI key on & engine off and 40 PSI at Idle.
Picture of FP gage under STB.

 

As an owner and tuner of LT1's (The LT-1 is the Gen 1 version from early 70's), here are the numbers:
Engine running with vac line disconnected and plugged: 42 +/-2 psi. Key on/engine off will show slightly less due to only battery voltage being applied to the pump. Idle with vacuum line connected will vary, depending on your engine condition and factors like cam timing, but will be in the mid-to-high 30's.