449er

I love the LS7, why? because I own one

Dreamer2

I don’t own a LS7 but if I did, heads would be examined and repaired. That is the tax you pay to own this legendary engine. The cars themselves are expensive. I could never drive around comfortably not knowing.

tommyc6z06

Exactly! I bought mine at just under 10,000km in 2018 and immediately got AHP Pkg 4 heads for peace of mind (stock cam for longevity and reliability)...2 days downtime at my local Porsche shop.
It turned out that a few of the valves on the original heads were close to outer limit of spec and a couple just outside.
While not a racecar, I don't just hard park it at the local show'n'shine, and do tickle the limiter on track
Would it have held together? Maybe...and how long? But why worry about it instead of knowing you've at least tried to mitigate risk.

Interesting history on all this...not so different from Porsche IMS, coolant fittings, or BMW bearings, etc etc

Kevin Mason

Or that guy who spends $40k on an engine, but puts Wally World Special tires on the same car. I have seen this more than once.

KennyPowers

Got a backup cause I like tinkering with stuff..

DANG2012

American Heritage

Yes

https://americanheritageperformance.com/

KennyPowers

Temporary, as in -> youll get LOTS of smiles and fun miles before you gotta do it again

DANG2012

So this aint a permanent fix to the problem? Im trying to get as much info as i can as im trying to purchase a 07 with heads done already by AHP. Im not trying to do this again

82LS7

Do you play with your car hard? like full throttle to near redline often? we do, my friends 66 C2 with the 570HP LS7 crate motor, 4500 miles, and mine, 82 C3 with the same setup,1,700 miles on my new motor, we just sent our heads to AHP, here is the report we got last week:

Your tear down/inspection sheet came back up to the office today.
The report found all 8 titanium intake valves bad and not reusable
4 of them have CRN coating flaking off on 45* sealing surface/angle and also have rough valve stems
1 has a large chip off the tip of the valve
3 have fractures on the edge of the valve tip.
All 8 will need to be replaced.

now this is with only 4,500 miles on a brand new LS7, and they mentioned that this engine was about to have a verry bad day. so glad we tore them down early to get upgraded! currently there getting the works!

Too-Fast

This is further evidence that GM/Chevy never fixed the LS7 head problems; mine were out of spec at about 2900 miles in my 2011 Z07, that I bought new...it did see runs to 7000rpm, was not modified at the time.

American Heritage

GM never did fix the problem with the LS7 heads thats for sure. Even the Crate LS7s that they sold (or still sell?) to this day have head issue.

https://americanheritageperformance.com/

grinder11

Send your heads to AHP for guides and a valve job, ditch the stock valves, and install Ferrea hollow stem stainless valves. Sleep better at night. I had AHP do my guides over 30,000 miles ago. I set up the installed height and installed the valves myself, using PAC dual springs. I've had no problems since. IMHO, not all heads are repairable for the long term. The valve job can be perfect, and if your rocker pedestals aren't machined the correct distance from the guide centerlines, or at the right distance above the deck height, or the pedestals have too much porosity to be non-flexible, they'll eventually take themselves back apart.

rockinSeat

Can someone measure what the right distance is so that we can save this time and trouble?

grinder11

You will never find that blueprint spec. GM wont release that info to the public. Only way you'll ever get it is if someone at GM, or Linamar, would spill the beans. Even if it was ever posted, you'd have a hard time verifying if the poster, and specs, were actually legit. In this thread, Hib Halverson was kind enough, and able to verify the OP is legit.

American Heritage

I agree with this statement
Kohle

https://americanheritageperformance....cylinder-heads

Tigerchevelle

can't wait to hear your results

grinder11

Yeah, I'm somewhat looking forward to doing it, but a bit apprehensive as to what I may find. I will say that stronger valves have a better survival rate against abuse and machining errors than the OEM GM valves, all else equal. But who knows whether my heads have the proper blueprint dimensions for the fulcrum pedestals as they relate to the cylinder head deck surface and valve guide centerline. I will say AHP did a fine job on the machining, and I went with their hardened PM guides, NOT the MS90 guides. Kohle said AHP's PM guides are harder than the GM PM guides. I think the real world answer is the high mile, 100,000 mile LS7's are probably outliers. We LS7 owners should probably realize that these engines, while not all out racing engines, probably require more attention than LS1's, LS2's, etc. To me, this engine is worth a rebuild every 50,000-70,000 miles. To others, it won't be. We shall see what I find.......

Tigerchevelle

if you go back and read the whole thread,he left before 09 so he doesn't know if they fixed the head issues or not.

Tigerchevelle

I just hit 79k on my daily 09. I
get it up to 6600,7k sometimes but I'm sure I'm in for a rebuild soon so I don't get crazy with it.
I did pick up a set of AHP heads with the moldstar90 guides and ferra ex valves.
I have the original heads to redo when needed.
I do wonder if the LS7 heads have more issues though?