Those of you that are running the LT4 HotCam, how many inches of vacuum are you pulling? I just got my car running today, on an almost stock AUJP and the brakes are horrible if I step on them with the clutch in (engine idling). If I leave it in gear and then step on the brakes, they seem fine. By leaving it in gear, the engine is staying at a higher rpm, and producing a higher vacuum reading. I think I am at 11-12 in at about 850 rpm. Brakes fine when I am at 15 in or so.

I'm going to play with the spark tables and lean the bottom end out a bit tomorrow. Hopefully it'll get better with the timing change.

By the way, this was with the vacuum reservoir disconnected. I haven't tried with it hooked up.

 

Mine pulled 13-14" of vac at 750rpm idle. With stock brake booster, no vac reservoir, the brakes were fine. No hard pedal any time I used them.

I never ran stock software, tho, and I didn't use AUJP as my base image w/ the 6-speed. I found a Vette image that had manual trans, and used that as the base. Just didn't want any issues w/ the idle behavior, and figured AUJP wouldn't manage it right if it thought the car was in Park/Neut all the time.

 

I think 14 is the norm. I haven't tested mine, but the brakes are good.

 

Well, I tried it with the vacuum reservoir hooked up and didn't notice a difference. I played with the spark tables and leaning the bottom end out and got it to idle quite a bit nicer and its at 13-14 now. Brakes are working a hell of alot better now. I guess that 11/12 is really close on the booster's requirements. I think it might even gain another inch or two if I keep working on idle. Its still not right.

 

I was recently running the hot cam i was pulling 18" @ 850 rpm,but i also had total seal rings....funny story machine shop checked my valve guides said they were very good...well the thing smoked like a frieght train when i hit rougly 5000 rpm,tore the engine down needless to say backs of the valve were seriouly carboned from the oil being sucked past the valve guides

 

What is your MAP reading saying at idle?

 

i had changed it over to a carb setup....in the process of doing the HSR swap with pro topline 200cc's....hopeing for mid 12's

 

About 45 kpa

 

I usually see high 30's. What is stock idle MAP?

 

Mine is carbed, but 16" with my 600 cfm edelbrock, 15 with my 750 cfm demon

 

hmm good info im looking to get the same cam

 

Yeah mine runs about the same 17" with my 600cfm edlebrock. Around 14 with Demon 750

 

Posted 04-09-2006

One would hope he has sorted his problem out by now

 

Lol. Yeah I was searching for something and completely missed tge date.... Lol