I have just finished rebuilding and installing a 396 cubic inch LT4 motor in a 96 vette. Eagle rotating assembly, 6" rods, AFR 210's, cam motion solid roller-- 254 264 @.050 .686 lift. The car came to me running but missing, I didn't drive the car as I found it had a lobe down on the #5 cylinder. When it's cold it runs great--idles good and everything, when it warms up tho the idle starts to fluctuate and this is followed by what I consider to be spark scatter, bucks and jerks, So I had to limp it back to the shop this afternoon about 3 miles. Within a half mile of the shop it smoothed out and ran great--for about 5 minutes then started doing the same thing again. I have changed both the coil and the ignition module. Fuel pressure is around 55-60 Has anyone had similar symptons with the distributor??? I haven't been able to get the scan tool to communicate with the vehicle but found some numbers on the PCM just before coming home--will see if they are different from the vin and retest that, in the meantime I hope someone here might be able to help!!!

 

You found it "had a lobe down in the #5 cylinder"? You mean a wiped cam lobe?

Don't run it at all if that is the case.

 

No I had the camshaft reground--was just implying that I don't know if it had this problem beforehand because I didn't drive it.

 

Well with a solid roller the "mechanical sounds" of the valvetrain will be interpreted as "spark knock" or misfire by the pcm and the timing will retard, has the computer been tuned and the knock sensor desinsitized?

 

Why is the fuel pressure so high?