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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
I spent the last hour looking for it. There are literally so many posts on this issue and I thought I bookmarked it but didn't. All I can recall is that it was referenced in a forum post here as one of the leading authorities on the valve guide issue and was close to 20+ pages long. It referenced the different fixes and addressed the problem in depth. I will look for it again tomorrow. I cannot recall the author.
I think he's referring to the CAC article. There may have been a little bit of a "situation" between the author and AHP, that caused the merits of MS90 to be downplayed. I'll leave it at that...
In any event, that article states that a metallurgist had mentioned that manganese bronze was just as reliable and durable. I humbly disagree...but thats my own opinion.
I think he's referring to the CAC article. There may have been a little bit of a "situation" between the author and AHP, that caused the merits of MS90 to be downplayed. I'll leave it at that...
In any event, that article states that a metallurgist had mentioned that manganese bronze was just as reliable and durable. I humbly disagree...but thats my own opinion.
The only "knock" one may be able to play against Moldstar 90 is that it is expensive and for most street driven vehicles, overkill. (Same could be said for your dry sump oiling system, too.) But, if you're a Nissan GT-R or LS7 guy who has inherent valve guide issues to solve, Moldstar 90 is well worth the extra coin.
so... are any of those fixes from those heads company addressing the casting manufacturing error where the guide is not centered to the valve seat??
Yes. The LS7 valve guide geometry issue is corrected by using a concentric valve guide, installing the guide correctly, and then performing a concentric performance valve job.
Yes. The LS7 valve guide geometry issue is corrected by using a concentric valve guide, installing the guide correctly, and then performing a concentric performance valve job.
dang! and still has issues...wow...I thought canted valve big blocks had issues but this takes the cake!
.........maybe I'll go back to my old stomping grounds and buy another Mustang - those Coyote motors are doing some great things especially with boost. We'll see what my inspection comes out like at the end of the month. Sometimes reading this forum blows !
.........maybe I'll go back to my old stomping grounds and buy another Mustang - those Coyote motors are doing some great things especially with boost. We'll see what my inspection comes out like at the end of the month. Sometimes reading this forum blows !
or you can go with a ls3 grand sport and boost the crap out of it
I think he's referring to the CAC article. There may have been a little bit of a "situation" between the author and AHP, that caused the merits of MS90 to be downplayed. I'll leave it at that...
In any event, that article states that a metallurgist had mentioned that manganese bronze was just as reliable and durable. I humbly disagree...but thats my own opinion.
my personal opinion, I agree on all counts and to amplify, the way I read the article was some said MS90 was not a great alloy which seems disproven by tested results above. The second point was it was a waste because it's not a top fuel or funny car WHICH seems to disprove the original point about it being a bad alloy, and the second point being it's a waste for the LS7 BUT it's about a $500 upgrade from AHP and that's chump change compared to the $15k-$20k a dropped valve costs you. Bad points in the article IMO but full disclosure I am biased by the fact that I already picked MS90 guides.
Would switching to an aftermarket head (TF, Brodix, Mast, etc) fix the valve issue?
I have been considering going to a Mamo TF heads and cam set up ....fixing the valve issue would be another reason to switch.
IMO (based research/links available in this forum), I would assess ANY head not manufactured by Linimar would be a "fixed" head. Unfortunately, anything that is a GM casting has a high probability of being affected.
Personally, I'm going to switch to TFS. My switch is based solely on I have yet to observe a failure of TFS valve train related parts or castings. Could my logic be flawed? Perhaps. Time will tell. In the mean time, I feel like I'm playing with fire.
Last edited by Pb82 Ronin; 04-04-2018 at 01:53 PM.
The only "knock" one may be able to play against Moldstar 90 is that it is expensive and for most street driven vehicles, overkill. (Same could be said for your dry sump oiling system, too.) But, if you're a Nissan GT-R or LS7 guy who has inherent valve guide issues to solve, Moldstar 90 is well worth the extra coin.
Exactly...since when is the Z06 community concerned with "overkill". I actually went with MS90 because it was overkill.
my personal opinion, I agree on all counts and to amplify, the way I read the article was some said MS90 was not a great alloy which seems disproven by tested results above. The second point was it was a waste because it's not a top fuel or funny car WHICH seems to disprove the original point about it being a bad alloy, and the second point being it's a waste for the LS7 BUT it's about a $500 upgrade from AHP and that's chump change compared to the $15k-$20k a dropped valve costs you. Bad points in the article IMO but full disclosure I am biased by the fact that I already picked MS90 guides.
Here’s the positive!! Khole at AHP has work with and resolved this issue for
Many years and in MHO and the facts speak for themselves. He has had ZERO issues of his repaired heads. I myself am thankful we have someone skilled enough to solve the problem. I have heard of so many stories of people who strictly race their LS7, then rebuild the motor when
Needed. They remarked that while tearing the engine down for rebuild, they check the valve guides, and they are still perfect shape in terms of clearances and wear! There is a reason why AHP offers MS90 guides for
Durability. There is also a reason why NASCAR engine builders use this material. AHP has some process of treating the valve coating which I’m not knowledgeable enough to describe. Their PM metal guides are very successful as well for street. As for me, I don’t race or track the car but
I wanted the best bc it made sense to invest in the best when your talking
$15 grand just for the engine. AHP is now receiving heads for others rebuilders to resolve their issue once and for all. I am not paid, or asked to
Proclaim their success and skill, customer service. I deal myself with facts. The LS7 is the best race engine ever made and it’s iconic.
NOW having said all this, GM let themselves “Down” and let the enthusiastic gear heads down!! It is heart breaking in the History of GM AND THE CORVETTE to not accept the responsibility to research and repair,
To correct this issue. GM has shaken my trust that I have had for so many
Years. GM has sold themselves out, cheapened their reputation, I thought
That they were better than that! I’m so disappointed. Ed Cole, Duntov, and many others must be rolling in their grave. When it comes to responsibility, character, and credibility, they sold themselves out to one thing, MONEY. They had and have so many options. They know exactly how to have cured the problem.
I’m sorry if I offended anyone, forgive me, it is only MHO. I don’t proclaim to know everything about this issue and I possibly could be wrong. If I am please correct me. I have been an enthusiast since the early 60’s and it frustrates me. Thanks for your understanding.
i had AHP do there moldstar guides and ferrera exhuast valves and a .020 decking.
i have a .635 lift cam
dual springs
car is a race car, spends nearly every mile on a road course at 3k-7k
i plan to keep the car for 10-15 years. i did my last car.
is there something else i can do with the to aid in further bullet proofing it? ie roller rockers were mentioned. im embarrased to say im not familiar with what a shaft rocker is, that was also mentioned.
i have no interest in removing or machining the heads. ie something i can do by pulling the valve covers.
what a shaft rocker is, that was also mentioned.
i have no interest in removing or machining the heads. ie something i can do by pulling the valve covers.
Cant do shaft mount on OE LS7 heads without machining though. Aftermarket castings...whole different ball of wax. TFS, Mast, can be purchased already set up "as cast" to accommodate a shaft rocker system.
As far as your current setup and current use...routine inspections are a must IMO. New springs every so often.
Hopefully we don't have another round of fixed heads that everyone will need to repeat
DH
No crap!!!
We have found that in many cases, if someone keeps the oil fresh, use quality oil and allow engine/oil to warm up (especially after getting heads fixed), then many of these so called “I fixed my heads” and now I having issues are non-existent. I am a big advocate of doing things on the over kill. Meaning, if you're going to fixed heads then go out and spray a NOS, install a blower/Turbo and so on, then please by all means change plugs and oil frequently. Use quality gas, allow engine to warm up, don't bounce off the rev limiter live a Honda Civic driver and please, please, please have a good quality tune…lean is not always or best approach, and too much fuel (super rich) is not always best either.
04-03-2018, 11:04 PM
My switch is based solely on I have yet to observe a failure of TFS valve train related parts or castings. Could my logic be flawed? Perhaps. Time will tell. In the mean time, I feel like I'm playing with fire.
