LVZ2881

iTrader: (4)

Got an issue with my car that I was hoping to get some advice on. Car is a '95 TA with 121k that the previous owner, when a headgasket went, put on rebuilt heads, Lunati cam and valvesprings, and aluminum full roller rockers (they appear to be summit brand) on about 3 years ago. I bought the car needing a few issues corrected about 2 months ago and just took it tonight for the first long drive around town with my wife. I noticed on the way home that once i started getting it up in the RPM's (above 2500), it felt like it was either surging or missing a bit( I thought it was because of the cam as the PCM has never been tuned, which is my next project), but i didnt notice any noise as we were on the freeway with the ttops off. Once I got off the freeway and on to regular streets, I noticed a tapping noise that gets louder with RPM increase. I'm concerned that a rocker may have backed off (there are posi-locs installed), or a lifter may have gone **** up. I need to know what to look for as far as lifters? I know if I take the valve cover off, a loose rocker will be pretty apparent..



also, when I had the valve covers off to replace the gaskets, the covers dont look clearanced for them, and I thought stock covers needed some clearancing for roller rockers?? Is it possible the rocker is hitting the cover, and It's just now making itself apparent? I'm thinking no because of the surging/missing issue..

speed_demon24

iTrader: (6)

It's most likely an exhaust leak. Rockers shouldn't loosen up unless the installer had no idea what the hell he was doing. My last ticking episode was actually a broken spark plug.
And the clearancing is so the valve covers will fit between the rockers, it has nothing to do with the moving part of the rocker arm. You probably have some narrower lifters that don't need to be clearanced.

http://s86.photobucket.com/albums/k1...=VIDEO0003.mp4

ADM

Did you open the valve covers after the noise began?

I had that noise, turned out the locking screw in the polylock came loose and the rocker arm jumped off the spring and was tapping on the spring's retainer (the pushrod was still positioned in the rocker arm).

leadfoot4

iTrader: (1)

WOW!! Were you lucky! I had that happen once, a LONG time ago, the pushrod popped out of place, and became a 3 pc. pushrod as it made it's way to the oil pan....


FWIW, I have GMPP roller rockers on my '96 Z-28, and I didn't have to mess with the rocker covers. They cleared...

96lt1m6

iTrader: (31)

James,
do you recall the last time i was there i looked through the oil fill cap and commented about the "BLUE ROCKERS" people have had problems with pro-form rr they could be scorpions too......When will you have time off so we can look the car over? Just call me..

JAKEJR

My son is running 1.7 & 1.65 Scorpion full bodied, 7/16" stud RRs on his 96 LT1 Vette without having to mod the rocker covers. Stock covers just dropped right on. No gasket change needed either.

If the rockers are hitting there should be witness marks on the underside of the covers, noise or the covers just won't drop down flush on the heads.

GM used different re-enforcement webbing for different year and models so it's basically a 'flip the coin' kinda thing. What worked for my son may not work for you.

Jake

LVZ2881

iTrader: (4)

It sounds like its coming from the front of the pass. side. Got the cover off, bumped the motor over a few times, and several rockers seem like they are slightly loose, but nothing is standing out as the cause..I'll do some more diag tomorrow when a friend comes over.

I'm hoping like hell its not a rod/main bearing gone...

the noise doesnt start until it gets upwards of 2000/2500 rpm...

I always thought a main/rod bearing gone bad would be apparent as soon as the car is started/ at idle???

ADM

Have you checked if you can move the polylocks by hand? If yes then the inner screws may have come loose.

You shouldn't be able to raise the rocker arm upwards from the valve tip either after just having run the engine.

I pulled my intake to check my lifter and cam lobe for damage, and they were good. But the spider leg holding down the lifter dog-bone for that set of lifters was bent upwards.

LVZ2881

iTrader: (4)

I'll check the poly-locks for tightness tomorrow before my buddy gets here...
at this point i'm hoping for the best, but planning for the worst( the bitching i'll have to put with from my wife if I need a motor, cosidering i just bought the car and sunk some $$ into repairs, will be ungodly)

considering that while driving it last night it was missing @ the same time it was making noise, I'm hoping it might be a combo of loose rocker/poly-lock and maybe a bent pushrod...

leadfoot4

iTrader: (1)

Just an FYI... On their poly-lock nuts, ARP recommends that the locking set screw be tightened to 22 ft/lbs.