APT

[Paul]

I adjusted the APT today on my quadrajet 17057266 carb. Started with 3 1/2 turns from bottom out, to rich aparently, using the tip in proceedure, ended up turning the adjusting screw in, clockwise, just over 2 full turns. So the adjusting screw is around 1 turn from bottom out tight. Is this ok? I have yet to drive the car. Primary jets are 74, primary rods are 44. The engine is a pontiac 455 30 over with #13 heads, 9.5/1 compression. Comps XE284H cam.

[Cliff Ruggles]

74 jets are too large for that carburetor and application.  I use the same carburetor, on a 455 over 550hp and use 73 jets, our custom 44 metering rods, and have full control of the APT from rich to lean......Cliff

[Paul]

Cliff,   The jets and rods I purchased from you. So do You recomend 73, or 72 jets?

Thanks,

Paul

[Cliff Ruggles]

The XE284 cam is HUGE for what you are doing, so it's going to be tough tuning it at idle and low rpm's.  It may be difficult to notice a change in "tip-in" rpm's. 

I would install 73 jets, our 44 rods, and start out at 3.5 turns up with the APT.  Set the float to 1/4" at the "toe".  Fuel pressure should be 6-7psi.....Cliff

[Paul]

I've installed 72 jets, float is at 1/4 and pump is at 7 psi. As soon as the distributor is done getting recurved  I will try adjusting the carb again. Hopefully with that and timing adjustments the vacuum will come up some. Paul