I really didnt go with the LT4, but the cam i chose was close. its a Xtreme 218/224 .496/.503 112 lsa with 1.6 rockers. Right now it seems to idle at like 1000 with the IAC plugged in and 500 unplugged (yea the car shakes cause its low) What do you guys like and what good for the driveability. Also I am running TF heads and I still have the stock chip. Will the stock chip be good for the first month of driving it around and working out the bugs? BLM's at 1000 are 127/127 and at idle they are 128/128 O2 readings are from .090 -.800 So I think that is good. AlsoI have it set at 6* timing. Anybody have a good marking? 8 ? 10?

 

btt

 

With the LT4-HOT cam my engine likes 750rpm idle, anything below 700rpm and it shakes the car noticeably. I ran stock software for several months and observed decent closed-loop behavior, BLMs were within 128 +/- 8...it was WOT and TCC lockup that drove me into PROM burning.

For initial timing, I noticed anything above 10degBTDC caused the idle speed to fluctuate between near stalling and 900+rpm when I came to a stop. This happened even when I set the ref angle accurately in the PROM.

Get a vac gauge and verify you're pulling decent (10-14inHg) vacuum at idle. Mine pulls 12inHg at 750rpm just for comparison.

 

I also get a good 750 rpm idle out of my LT4 Hot cam. 6* initial also.