r2boxers

I am aware of the vendors that are rebuilding LS7 heads for guide issues. Just wondering if Lingenfelter does this also? All responses appreciated in advance.

MTPZ06

Yes, they offer CNC ported heads, and PM guides. Not sure whose PM guides, and what metal composition they are though. I imagine they know how to do a concentric performance valve job...something Linamar cant seem to do.

The biggest thing to me then becomes wear of the guide material over time...is LPE's PM guide material the same composition as OE? If so, I feel its too soft...same goes for bronze. No one really knows much about LPE's PM guides.

Bronze Manganese would be an upgrade over OE guides; but AHP's PM guides or even better yet, their MoldStar90 guides are just superior in every way.

MTPZ06

I know its in quite a few threads, but for reference purposes with regards to my comments above on guide hardness...this is AHP's independent test on various guide materials. Ultimately, this is what convinced me to go with MS90. MS90 becomes harder after use, no other compound does that.

American Heritage

Rest in Peace John Lingenfelter (one of my personal idols).

Our Moldstar90 Valve guides are hands down the best guides on the market! They are truly an out of this world alloy. Formula 1 and Indy cars run Moldstar90 for a reason. Moldstar90 handles high heat with ease and as mentioned above Work hardens. This means the longer its used and the harder its used the stronger it gets!

http://www.americanheritageperforman.../services.html

Undy

I believe Lingenfelter is one of the few shops that use GM's OEM guides. From what I remember they can obtain them due to their close relationship with GM. Personally, I wouldn't use OEM GM guides. Draw your own conclusion though...

MTPZ06

I had heard that rumor as well...never heard if it's been substantiated or not. If true, I agree...there's far better choices out there.

r2boxers

I believe you are right! Will be going with AHP heads. Just got off the phone with them.

yellowzron

I called them to see what they did on a zr1 I was gonna buy. They were very helpful and spoke to me at least for 30 min. Customer service was awesome. The only thing I could not understand was, they are firm believers in using OEM guides. I have no idea why they do, but if I was gonna re do the heads, NO WAY would I use OEM guides. Just my 02 cents.

1972bluelt1

I've wondered this stuff myself since they are near my home. I guess it doesn't cost anything to ask if they use or can use MS90 guides. I know on some of their high end builds they use inconel exhaust valves.

American Heritage

They dont have MS90 valve guides only We do!!!
We are the only ones to use MS90 valve guides in any LS head.

We make our guides locally to our extremely picky specs. They are extremely pricey and time consuming to make.

http://www.americanheritageperformance.com/

User Omega

Great choice. One of the best shops I have dealt with. I will definitely do business with them again.

OnPoint

I had Lingenfelter work my heads while they had my ZR there doing some mild hp enhancements.

Thye machined the heads and replaced the guides. They use OEM guides, and state the most critical aspect is getting the machining right, which apparently wasn't on my ZR from the factory as all the guides - intakes and exhaust - were out of spec.

Just passing along, fyi. Not arguing one way or the other on which guides to use. I do feel better that my heads are machined right, tho.

nuke61

I don't think there's anything particularly wrong with the OEM guides. After all, the LS6 motors had sodium filled exhausts and PM guides, and I think the latest LT motors have the same combo.

outhouse

They are to soft for the LS7 application, no debate about it.

Tech

LOL.. If you say so.

I wouldn't hesitate using OEM guides. If the guides are not machined correctly, something is going to wear prematurely. Fix that problem and the guide material is a non-issue.

Not everyone is building their car for LeMans.

yellowzron

There have been numerous problems with the ls7, there have been some dropped valves with the ls9, hard to tell since not everyone who owns them are on this forum. But there seems to be a problem here and if anyone thinks there isn't then thats ok. Its up to the owner to address the problem.

Tech

I don't think Nuke was saying there weren't/aren't problems with dropping valves. I think he was saying that the guide material likely isn't the root cause. Maybe the valves would have lasted longer with a MS90 or bronze guide, but the problem is actually the machining or finishing of the parts.

nuke61

I disagree, because there are all those LS6 and LTs out there with the same setup. The difference? Quality machine work, and not the non-concentric work that Linamar did.

If the problem was PM guides, or spin-welded sodium filled exhaust valves, we'd be hearing all sorts of problems from all the LS6s that are much older than LS7s, and now with the LT motors. The difference is that the LS7s have known non-concentricity of the valves and valve seats. Lingenfelter uses the same heads on their warrantied work, so that shows their confidence in PM guides - as long as the machine work is up to snuff.

outhouse

I don't say so. AHP even shows you how soft they are. the problem is not all the machining process, the problem is dynamic and reworked head with proper tolerances and harder guide material are already wearing out early due to the aggressive valve train.


So it snot me, it the actual knowledge of the problem in detail.

outhouse

Disagree all you want.


Heads with harder material that were machined properly have already worn out from WCCH and been replaced.


AHP guides with the harder material are showing almost no wear at all.

MTPZ06 posted the hardness for a reason.