96LT1TX

I definitly agree.. I dont think the ex-612 valvesprings are any good to .580" lift either
that could explain almost everyone who has posted's problems....valvefloat. my 230/236 goes to .555" and I kinda wish I did meaner springs, beehive sounds good to me too... If I had the heads off again, it would definitly be beehive time.

RealQuick

subcribing...

94_Z28_ragtop

Anybody ever get any resolution to this problem? My old car is dropping off at 5800 rpm. Was also told it was valve float. It has a Combination Motorsports head/cam package with less than 4K miles on it. We pulled a valve cover and there were pieces of what appeared to be valve spring in there. We will be taking it apart this weekend to see how bad it is. I'm hoping to not find any bent pushrods. I assumed (unfortunately) that the valve springs were Comp 987's because I was told they were good to 0.600 lift and the O.D. measures the same as a 987. New 987 springs were purchased without retainers and locks because we were going to reuse the old ones. I'm going to have to call Combination Motorsports tomorrow to see what kind of springs they put in it now. Also using stock Comp replacement lifters and Pro Magnum 1.6 rr's.

Also, unless the heads were flat out set up wrong (which I highly doubt), I definitely don't blame Combination Motorsports for this failure!

MachinistOne

Do any of you guys have spec sheets for your motor builds...as in what installed heights, spring pressures, coil bind clearance? I'm not saying that some of you do not have valve float, but I have seen in many cases that the main cause of a dyno graph that peaks, then holds a hp number for a while before dropping is a VE problem, if you still have that single exhaust, you may have too much backpressure, I have picked up over 120hp in some cases by throwing good exhaust on a car. My shop has a dyno dept so I see this a lot.
Now if you are running true dual exhaust my theory is wrong. Find out the specs these guys are setting your motors up at and I can help.

94_Z28_ragtop

Unfortunately they didn't give me the specs with the heads. Plus, I know I have a problem because I actually have at least one broken valve spring. I forgot to mention before, I'm reunning an XE230/236 cam w/ 1.6 rr's. Cam is 0.510/0.520 lift and even with the 1.6's it's at or below 0.550 lift.

limige

I bought a valvetrain setup from combo a few years ago, they didn't include a spec sheet for the springs giving the install height, coil bind ect. i'm assuming they are the 987's using stock seat and supposed to be good for .600 lift.
i sold the 224/236 and picked up a xe230/236, so this thread makes me wonder.

warning to the person who started the thread, there is alot of stuff going on with APE checkout the motown muscle board on this topic. a buddy of mine recently had his car there and he's been having issues as well. just a warning, i wouldn't just assume it's valvefloat because he said so.

my suggestion is instead of going with larger springs install a rev kit, it'll help much more!

let me know if anyone has any luck with their problems.

mike

Elysian

I had valve float, and it was for sure the springs. I talked to Dave at CM and ordered some new springs from him (Comp 978's to replace the EX series springs). I installed the new springs and drove the car up to AP Engineering to put it back on the dyno. I picked up ~20hp and about 400rpms. It was definitely valve float. Probably just a bad batch of springs. Props to Dave at CM. He was really helpful.