LS7 Failures in the Z/28's How Many?

[DasBaldDog]

Originally Posted by 1970judge

I disagree, its an inaccurate test. GM agrees so they dropped the test method. Everyones BELOVED KATECH also agrees. Throughout these threads, people claim to have read all of the info, all the articles, all the bulletins, then show up and recommend an outdated test that even their preferred shop has disavowed.

Katech is quoted as saying its not accurate.... and its hard to define a pass/fail limit... but there IS information to be gained from a Wiggle test.

As for GM, they dropped it for being less than definitive and seeing that it was going to cost them massively. The test IS inaccurate but not useless.


The test has quite a bit of value but its results cannot be directly equated to a specific valve guide wear, etc.


I NEVER said I recommended the test.... I said that the test is not wholly without value. There is ALWAYS information to be gained from any test on just about anything.

[1970judge]

Ok, I take it back..I agree with you sort of. Tear it all down, grab ahold of the valve stem and jerk it around. If its hella loose, sure, valuable data. Do the wiggle test with a gauge and see .1 which is a wallered out mess and waaaaaaaaay over the .0037 limit, sure valuable data. Do a wiggle test and get .0025, more precise measurement is needed.

So what was gained by doing a wiggle test when there is more precise methods available? Congrats, you opened it up and found a valve thats been shaped into an hour glass, OR, you wasted your time performing a test without defined limits and will now move onto the actual proper way to determine if it has an issue.

So yes, i take it back, there ‘could’ be value on the test.

[Biergut]

Originally Posted by 1970judge

If you have warranty left, i cant begin to understand the reason why you would preemptively do anything.

A) it pops under warranty, they fix it...under warranty, and you have nothing more than a crummy afternoon waiting on a tow truck.

B) GM decides to say, nah man, you opened your hood that one time, warranty voided, replacement denied. You spend your dime getting new heads.

C) You spend your dime getting new heads, preemptively.

Option B and C cost the same, save for a 100$ tow bill? Option B only costs a little more if you’re trying to slide one by the dealer. Which, you should know going into the deal that, there is a potential they’ll deny me because i installed this or that.

What is option C gaining you? Other than keeping your car off a flat bed, maybe, one day.

If its got warranty, let it ride. IMO of course. Once the warranty is up, sure, maybe i’ll call KATECH and upgrade some things here and there and if business is really good i’ll build an engine to my personal liking. Otherwise, like I mentioned to some buddies recently: i fall into the “im going to shift this mother****er at 7k, if it holds great, if it doesnt, great [on the track, im not a highway jackass]”. Im a realist.

Agree... the only logical solution I came to as well. Day it's out of warranty -- it's headed to the shop.

[1970judge]

Originally Posted by Biergut

Agree... the only logical solution I came to as well. Day it's out of warranty -- it's headed to the shop.

I wont do mine “day of” and it wont be out of fear of the valves. It’ll be because i feel its time to step up the power a bit. But yes, logical for me is at the very least, wait until warranty is up. Unless the engine gods decide I should be beset with faulty valves and the engine unloads...then..see above A,B,C options.

[carparts]

Problem i see with waiting
If it does drop a valve which is what i believe happens most often and its fixed under warranty you no longer have a matching numbers car. I had my heads done by WCCH who i believe did most of Katech LS7 heads till they brought it in house. Like all collector cars people want matching number cars.

[Biergut]

Originally Posted by carparts

Problem i see with waiting
If it does drop a valve which is what i believe happens most often and its fixed under warranty you no longer have a matching numbers car. I had my heads done by WCCH who i believe did most of Katech LS7 heads till they brought it in house. Like all collector cars people want matching number cars.

I am not sure that is necessarily true... if GM replaces an engine and it's all on the books - it really shouldn't affect the long term collectable value... and some may find the story interesting. (provided it's a factory warrantied LS7 from Wixom or BG) However, I surely doubt this car will be worth the kind of money we're dreaming about for a very, very long time -- long after I'm gone and regardless, the heads will be done at by that time anyway.

[MrRaZ28]

I will never understand the obsession with matching numbers anything. My prediction: these cars will never be worth the money that the 50's/60's/70's/ cars sort of are, depending on condition. Too much electronic stuff, even in our cars, for it to last.

I.e. Drive the damn thing! It's meant to be driven! lol

[4 FN 27]

Originally Posted by Russell James

The only way to measure valve stem to guide clearance is disassemble, mic stem and guide in 3 places then do the subtraction.

I agree. The wiggle test is an OK starting point. Obviously if it move .125 there is a problem. But as the article points out it is hard to define the limits.

Back in the day we used a Faro Arm CMM to digitize the entire Head and check the tolerances.

I bought this Romer Arm home a few weeks back. It will be perfect for checking the Concentricity and anything else that matters.

[1970judge]

Originally Posted by carparts

Problem i see with waiting
If it does drop a valve which is what i believe happens most often and its fixed under warranty you no longer have a matching numbers car. I had my heads done by WCCH who i believe did most of Katech LS7 heads till they brought it in house. Like all collector cars people want matching number cars.

What? By that measure Yenko Camaros arent worth anything either. Those arent numbers matching cars homie, they’re conversions. BUT, they’re some of the most sought after. Dana, Baldwin....etc. Last I checked GM didnt offer a 427 4th gen, but a Dick Harrell car WILL set you back in the wallet a good ways.

That logic is

[BJJKRIS]

The heads don’t have any numbers to match. Just an etched on part number. No VIN. Btw if I was a collector years from now and I bought one of these cars and then found out that it had the original heads I’d be a little upset. Like “great, the previous owner didn’t fix a known issue and now I have a time bomb”


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[Shoupaloop]

What is the car market going to be down the road when Millenials are middle-aged? I going to suspect that it's going to be in stuff that we don't conventionally think of as cool. It wouldn't surprise me if there was a larger market for a Tesla versus a big CID muscle car. Maybe the interest in cars won't be there at all. Maybe it will be I-pods or other electronics. Perhaps it will be in diesel trucks. Just throwing out thoughts, but I don't see the market getting more robust and driving prices up.

[Biergut]

Originally Posted by Shoupaloop

What is the car market going to be down the road when Millenials are middle-aged? I going to suspect that it's going to be in stuff that we don't conventionally think of as cool. It wouldn't surprise me if there was a larger market for a Tesla versus a big CID muscle car. Maybe the interest in cars won't be there at all. Maybe it will be I-pods or other electronics. Perhaps it will be in diesel trucks. Just throwing out thoughts, but I don't see the market getting more robust and driving prices up.

I think there will always be interest, but the issue I see is the gasoline and more than likely special permits in order to burn it. Lime Rock Park has only a few certain days they allow unmuffled sound... I see that type of restriction on using gasoline engines in 25/30 years. The United States is going green like it or not.

[Jeff71]

Originally Posted by 4 FN 27

I agree. The wiggle test is an OK starting point. Obviously if it move .125 there is a problem. But as the article points out it is hard to define the limits.

Back in the day we used a Faro Arm CMM to digitize the entire Head and check the tolerances.

I bought this Romer Arm home a few weeks back. It will be perfect for checking the Concentricity and anything else that matters.

Nice shop, sir.

[Gbland60]

Originally Posted by BuckeyeROC

Agreed.

+2. Be like Been there .