how do you know what to set your fuel pressure at? my L98 with an LT4 hotcam with 1.6 rockers seems to still be pushing too much fuel in the cylinders... last time (couple of months ago) that i attempted starts on this new engine showed a lot of fuel that got in to the oil. it doesn't appear to be that bad this time, but i had a problem with it yesterday so i checked one of the plugs today when i got back in to it and it was wet with fuel. last time, pressure was set at about 47 w/no vacuum, this time it's set at 42. fyi, new rebuild on the entire engine... i thought about putting the gauge on it and letting it sit to see if it bleeds down, but i had the injectors serviced, too, and they all checked good...

the engine is now about ready to go, other than to set iac, timing, and idle, but i'd like to know what i need to do with the fuel pressure, too. how is the air/fuel mixture adjusted?

KAM

 

Are you using a custom PROM? What size injectors?

You realize that the LT4 "hot" cam has quite a bit more duration and therefore overlap than the stock L98 cam, right? That will cause a lower vacuum at lower RPM, and the ECM will interpret the higher MAP as more load, and apply more injector time.

Might be time for a PROM burn. You could lower the fuel pressure to compensate at lower RPMs, but would not want to risk going lean at higher RPM and throttle openings.

 

I have that cam I run 42 psi with 24lb injectors..This equates to 39 psi at idle with vacuum to APR. I also have custom prom. I didn't burn the chip so can't say how much it is altered from stock. This is on a 383. Pull a plug yesterday and looks lean if anything.