Z.06

For those of you who held GM to be responsible for the excessive valve guide wear problem, and had GM replace the heads and valves under warranty, your worries are not over. While GM swore that the replacement parts had fixed the problem; they lied. A friend of mine on the forum told me that he had found his valve guides on his replaced heads were out of spec within 15000 miles, so I decided that when my car reached this mileage on my replacement heads, I would have it checked to see if mine was indeed fixed. Not feeling like repeating the wiggle test myself, I tried to get area shops to give me a quote for the work. The quotes were not reasonable and I asked myself whether I really want to be redoing this check every 10-15,000 miles to make sure that my valve guides are out of tolerance. Finally, I decided to bite the bullet and send my heads to American Heritage Performance for rebuilding with their Moldstar 90 guides. Before I could remove the heads, fate stepped in and set me up for a bigger rebuild, but that is another story in another thread.

When my heads reached AHP, they were checked with a wiggle test and here is the result. Remember, for a wiggle test the acceptance criteria is 0.008"

1 int: .008
1exh: .006
3 int: .008
3exh: .006
5 int: .009
5exh: .007
7 int: .009
7exh: .006

2 int: .010
2exh: .007
4 int: .008
4exh: .006
6 int: .009
6exh: .007
8 int: .008
8exh: .006

So 4 intake valve guides were already out of spec in 15,000 miles, and the other 4 were at the limit. My heads were replaced in April 2013. So those of you with heads replaced by warranty might want to give these results a thought. Ditto for those of you with later model LS7 engines, those produced long after GM claimed to have fixed this problem. You may be ready to drop a valve and just don't know it.

I have done all I can by having heads remanufactured by AHP with the Moldstar 90 guides. I hope they last longer than I do.

Apocolipse

jayyyw

We know.

moose.b3

Yep, on my 3rd set of heads. This time I also did AHP with MS90.

no cigar

Just curious, but does anyone do these types of checks on aftermarket castings (MAST, RHS, TrickFlow, AllPro etc.)?

MTPZ06

What?! GM Lies??

Dan_the_C5_Man

No point in even bothering with GM replacement heads, even if you have to pay for a correctly built set on your own dime.

I had a factory warranty AND an aftermarket warranty - I cashed in the aftermarket warranty, invalidated my factory warranty, sent my heads to AHP.

freddyvette

You should have had your aftermarket warranty pay cash value for your aftermarket heads.

Dan_the_C5_Man

it was a GMPP warranty, paid for by the previous owner. If I lived near AHP, I could have (possibly - technically, the factory warranty was still in play) had them cover it, but I did not, so I went another route. I wouldn't let a typical GM tech near my car to declare them out of spec, much less repair or replace them.

freddyvette

You live near Vengeance racing. They could have used the invoices from parts paid to anyone in the US with a tax ID. Missed opportunities.

Stavesacre21

Nice to know. Always suspected the same too.

When I owned my 427, I always thought that having the heads worked over was the only way to ever sleep at night, regardless of everything you heard. Never got around to it as I sold it and picked up a ZR1...only to be dealing with the (equally if not more expensive) ceramic brake vibration issues now. I keep giving GM the benefit of the doubt and they keep poo pooing on me. Why am I back again? lol

Dan_the_C5_Man

I appreciate your input, but no, Vengance isn't touching my car. I am ok with how it worked out; sometimes a few hundred bucks is worth the lack of grief.

On to the next "problem" - thinking about proactively swapping the stock cam and lifters BEFORE they become problematic, in an attempt to avoid their likely eventual failure. Always something..

MTPZ06

With?

TXGS507

A Vengeance Racing cam..... lol Oh wait.... I run their Kaotic cam....

Unreal

ZR1 have head issues too, and intercooler brick issues, etc. Can't get away from GM quality

Dan_the_C5_Man

I am sure you've seen the numerous posts lately with etched cam lobes and lifters.. And those were examples that went so far that they made noise, etc., but I believe most of these failures start slow and progresssively get worse. The part that sucks is you can't inspect without pulling the heads.

That fuzz some of us see on the mag drain plugs is coming from *somewhere*.

MTPZ06

Les

This is the only "Me Too" movement I'll ever be a part of. I'm also on my 3rd set of heads- now done by AHP with MS90.

Dan_the_C5_Man

Ahh.. Well, it will def be from Cam Motion, and if I decide to keep the YT's (I'll pull the valve covers in a few weeks to check everything out) and the 1511's, maybe something between stock and their lowest-level perf cam - might even ask Kip to replicate the stock cam profiles but move the LSA around.. If he says thats not a good idea, I'll just ask them to cut me a stock LS7 cam.

On the lifters, seems like drop-in Johnson's are popular - will want something better than GM / AC Delco-specs in any case.

moose.b3

[QUOTE=Les;1598199822]This is the only "Me Too" movement I'll ever be a part of. I'm also on my 3rd set of heads- now done by AHP with MS90. [/QUOTE