Zeaux6504

After reading the many forums regarding the dropping valve issue, I decided to have my shop do the wiggle test. As it turns out, the intake and exhaust guides were out of spec, with the intakes being the worst. My Z06 only has 20k miles on it. I believe, given enough time, my motor would have experienced failure if I did get the heads reworked. I had American Heritage do a package #4 on my head, but I opted to get the Moldstar 90 guides installed instead of the PM or bronze guides. After talking to numerous professionals and manufacturers, I believe this was the right combination for me. Although the Moldstar 90 guides were about $500 more, it was well worth the extra few bucks knowing I have the best guides on the market. From what I understand, Moldstar 90 has all the benefits of both PM and bronze, but more durable.

My experience with AH was a very pleasant one. Kohle was very knowledgeable and the customer service with top notch. He returned my heads in the stated time frame (about 5 business days) and was happy to answer any questions along the way. So far, I am a happy customer. I will be sure to give updates to the forum as I rack on the miles on the street and the track.

Going with AH was not an easy decision since everybody talks about WCCH on the forums. For me, it just seemed that what AH was offering on their package #4 made more sense than just the default decision of using SS valves and bronze guides. Kohle’s knowledge and willingness to use the Ferreas and Moldstar 90 really help me make up my mind. I guess what I am trying to say is that if the consensus to the “fix” is SS and bronze, than using the Ferreas and Moldstar 90 is certainly a step in the right direction.

As aside, I hope this combination of Ferrea hollow stems, BTR springs, Moldstar 90 guides and QM550 cam prove to be a stable combination. I was recently made aware that Spintron testing was performed using the Ferrea hollow stems. I was not part of the participating forum members as I recently joined the forum. I hope testing validated my combination. Either way, I am still going to drive my car and enjoy every breathtaking moment.

Current mods on the car- QM550 cam, M2W, AR headers, X-pipe, halltech killer bee intake, tune by Quality Motorsports, 3.9 gears, and of course, heads reworked by AH.

'06 Quicksilver Z06

Well, good luck with the setup, but no, I don't believe that the recent testing results you make mention of above are going to validate that Ferrea hollow stems, BTR springs, and QM550 cam combination. I don't believe that it was one of the tested setups, nor do I recall any of the tests in that recent effort being anything close, in terms of components used, to the setup which you describe above.

At any rate, to your part in red, that is the most important point.

Good luck.

vertC6

No everything is the exactly the same including the cam, the only difference is the springs. I would change your springs to the PSI beehive 1511, they have more control than the duals, and the QM 550 is a low lift cam.

Kohle is the only guy I will send my heads to!!

Zeaux6504

VertC6, thanks for the input. People like you are the reason why this forum is so invaluable.

vertC6

Thank you for the kind words if you need anymore help feel free to PM me

Unreal

No one has tested that cam.

Glad to see reports of good customer service, but proof is in the pudding. Please post some dyno results, track results, or get 30k miles, check heads and report back. I want parts that work, not friendly phone chat. Not saying they don't, but all you can do is review his service, hard to say if the parts are working until someone uses them, put some miles on, and reports back.

vertC6

The cam was the QM 550, you can confirm it with Michael D

Unreal

You would have to ask carlos, but a QM550, QM600, or any of his cams actually change depending on user. If it was a QM550, doesn't mean it was the same QM550 if that was even one tested. I know I had a QM blackmamba, that was different from other QM blackmambas. Carlos custom does cams per the user.

Either way I'm sure you will be fine and good job getting something done. Just saw another car this week drop a valve because the owner didn't think it was a big issue and chose not to do anything.

DON T.

My thoughts exactly. I want parts that work! The First time. Dont have money to burn experimenting with this and that combo. I know without a doubt the combo i went with will last. Testing shows this. The pudding so to speak. I wish you success sir, that you have many years of enjoyment with your Z.

Zeaux6504

What I have gathered after reading all the research/posts/testing/testimony, is that any combination you use (i.e. SS/Bronze, Ferrea/PM, stock sodium/PM) will be the solution as long as the head work is done CORRECTLY with quality parts. The important point is there have been almost zero head-related failures post "fix", regardless of combinations used. If one want a tested combination that addresses the "valve bounce" issue, then one should use the combination that was validated via Spintron test that certain forum members carried out. If I had know about the Spintron testing before I reworked my heads, I would have paid my part and get the information. For me, it was too late, but am still comfortable with my decision. I do not have a test-proven combination, but also believe my motor will not blow up either. I hope time will prove that the LS7 motor is in fact a wonderful piece of American engineering, once the heads are addressed.

AZDANZ06

Thanks for your review, the reasons you listed are the same exact reason I am driving my Z over 8 hours to American Heritage in late December to have him perform the wiggle test, if out of spec his shop will R&R my newly rebuilt heads and I will come back after it is all done to drive it home. I spoke with several shops before making this decision as well as reading threads and feel this combination is what I feel comfortable with in the end.

Random84

To be fair, the Z06 isn't the first car to ever get a set of aftermarket springs with a valve job and a cam before.

Focus on having a competent professional and trust their judgement ( being more valuable than the sum of the parts). At the least, you bought another 40k more miles of confidence....

And by then your springs will probably need replacing anyway!

American Heritage

Thanks for the honest review Jetty and thank you for your business.

Your gonna love the Moldstar90 guides. They are the next big thing.

Also just to remind everyone we stand behind our heads 100%!!! Integrity is everything in life!

Now go beat on it with no worries!!!

Michael_D

That is correct. I do not know if Patrick is still using Cam Motion lobes or not, but the QM550 I supplied for the testing does. Also, QM sticks are Patrick's, not Carlos's. Those two often partner on projects, but they both have their own independent businesses.

DON T.

Im good with all you said, i did not know about spintron testing in 2012 when i went to Katech, Nor did i pay any $ when it was conducted again this year. I simply went with the advise from Jason at Katech in the spring of this year. And i also hope your correct that time will prove the LS7 WAS the best of the best all time GM motors! BIG-MOTOR!!!! I wish you the best. 100%

LMB-Z

I really would like to see the dyno sheet on that build, before and after.

FSTFRC

JameZ06

American Heritage is one of the best shop hands down. I'm glad I came to Kohle to have my motor done. I really enjoy driving the car hard after without the hesitation of the valve might drop.

MyLastCorvette

Before I had my heads rebuilt I talked to many shops over approximately a year. AHP does good work as witnessed by the satisfied customers.

For myself, it boiled down to the same as going to the Doctor. I get nervous when the Doc is about the same age as my Grand Kids. Doesn't mean anything, other than what one is comfortable with; Enjoy your Z, I'm sure she will run flawlessly for many miles...

American Heritage

The most miles we have on a set of our Package 4 heads is 50,000 miles (maybe a little over 50k now). We measured the valves at 45,000 miles and we had no measurable wear. In other words they measured almost identical at 50k miles as they did when we first put them on.

Mylastcorvette: I understand your thought process, when it comes to doctors i feel the same way as you. The big difference is in the automotive world you can start practicing/apprenticing/interning at a very young age (16) as opposed to practicing/apprenticing/interning internal medicine at a much older age (often mid/late 20's to early 30's). just sayen