Must_Have_Z

It's not just heads. It's not just rockers. It's not just guides. It's not just the metal material. It's not just concentricity. It's all those things. And that's what makes this issue so damn frustrating. There are good vendors out there offering solid solutions but every car is different, and used differently, so I honestly think there will never be a 100% bullet proof fix. My advice? Choose the best solution for your driving habits, mods and budget. And then don't just forget about it. Get the heads checked every 15k-20k miles and be diligent. Not sure what else we can do.

KEZ06

So I dont pretend to know the conpatibility, but I believe that some have used LS3 heads on the Ls7. Is the geometry more conducive to wear prevention? What is lost using the LS3 head?

Must_Have_Z

From hotrod.com (http://www.hotrod.com/articles/hrdp-...top-ls7-heads/):

"Though the LS7 castings share the rectangular ports of the LS3 heads, they up the flow ante with raised ports, altered valve angle and locations, and even larger titanium valves. Not long ago these factory LS7 castings would have been considered full race heads."

KEZ06

Thanks for the article. I will give it a read.

BigVette427

I heard someone say even with a fully ported LS3/L92 head, you lose about 20 rwhp right off the bat as opposed to an LS7 head. WCCH claims 354cfm at .600" lift on an L92/LS3 head where as on an LS7 head at that same .600" lift, they can get about 389cfm.

Also, remember that the LS3 rocker arm ratio is still at 1.7 compared to the 1.8 for the LS7 (and all subsequent Gen V motors, as well) so there is a slight reduction to the amount of lift that you're getting out of your camshaft, as well. You would no doubt just be better off going with Moldstar 90 guides on AHP's LS7 heads, and an LS friendly cam with lift under .650". (Like the popular 116 cams from Katech and AHP.)

KEZ06

Is guide play a check I can do myself or is it better to have a shop do the check? I have WCCH heads on an erl short block so of course interested in avoiding the valve drop issue. This car is about to be used for the track. So the last thing I want is a suseptible head issue as I start to stress the drivetrain.

v8sten

BTR Stg4 cam. don't know the exact specs anymore, but it was an aggressive cam. I was just doing what Brian Tooley said to do

Unreal

Changing valve springs ever 25-30k miles is normal and should be done.

MTPZ06

CYA for a smart business owner that doesn't want to put statements out in the universe that may haunt him at a later date. His springs should last way more than 25K...but it pays to be cautious with advice.


As others have mentioned...heads flow less (even fully ported), lower rocker ratio, different intake manifold. Plenty of drawbacks IMO.


Agreed. If you're running a more aggressive than OE cam, this just comes with the territory. I think Katech also recommends ~20K maint intervals. Thought process is along the lines of...a high quality, properly spec'd and installed spring should practically never fail in 20K miles...so if you want the best chances at "never" having one fail...swap them out at 20K miles.

BigVette427

I think the website text has changed a little over time, but previously some have listed that cam at 246/254, .652"/.630", on a 111 LSA. Today, it's listed at 247/258 on a 112 LSA but doesn't mention the lift. That's a lot of duration and regardless as to the lift, the lobe type would be as significant as the lift. Interesting what he says about the rocker arm side loading.

Due to the longer pivot length and longer scroll of the LS7 rocker arms up to .660" lift can be used without valve tip damage. We recommend maximum open spring pressure of 430 lbs

https://www.briantooleyracing.com/ls7-stage-iv-cam.html

It certainly shouldn't be normal for a production car! (I can't believe how CHEAP the valve springs are on the Gen V LT1/L86, btw!) But the LS7 is essentially a race motor that we all know comes with inherently poorly machined cylinder heads, so we have to go in and make some adjustments to save the heads. I still believe the beauty in the LS7 is in its cylinder heads, so to beef up the guides and improve the valve train with superior valve springs and exhaust valves, that's been part of the enjoyment for me in owning an LS7.

I figure by the time I get 25K miles more on my Vette (currently just under 7k) there will be ample evidence of comparable setups (Moldstar 90 guides and PSI springs) for me to decide whether or not I ought to pull my valve covers. Shoot, if TSP gets their new roller-tipped rocker arms right for the LS7, they might be a new go-to item that'll motivate me to get back in there long before 25k miles anyways.

Innovate

Katech_Zach

This is incorrect. We always use Ti/Mo intake valves in heads with bronze guides. There are no exceptions. We don't use OEM intake valves in heads with bronze guides. We would not risk our reputation doing anything less. So no, none of our heads have issues.

Unreal

To be clear, 25-30k for an aftermarket cam, not factory. If you swap to a big duration aftermarket cam, with big lift, springs at least need to be inspected, if not replaced every 25-30k. If it is all factory stuff, sure 100k+ no issues, but not with aftermarket parts.

racebum

high end bronze/mag is actually pretty hard. katech also recommends $3200 in valves they are very slippery via moly coated titanium. i think this is why they don't get a lot of speak on here. a set of heads done by katech will set you back about 4k, 5k if you port them. spending that much on valves is basically 10% of the cars value in many cases.

0Myhardtop

Yep...no issues here thus far, and lord only knows what we put these cars through

Note: one can easily say that I would champion hard for WCCH since they are one of our vendor plus due to the fact that we have been working together side-by-side for over 12yrs. But, honestly, we have not had any issues and just because we haven't, it does not mean others have not.

My advise:please talk to the guys at WCCH vs blasting on the forum. The forum can be a great place for info, but sometimes....

Thanks,
Carlos

rio95

corvettenutz

i always wondered if this is a dry start issue.

nuke61

Maybe another part of the puzzle, but I also think the horrible C6Z oil cooler is part of the problem. Rio95 lives in Michigan, and he once posted about how difficult it was to get his motor up to a decent oil temperature. I live in Phoenix and don't even run the stock oil cooler.

Unreal

Which I do think is part of it. Just like how we have seen locally guides shot in 10k miles from the people with huge cams, that just do them for sound, and to rev it to 7k at the car shows on a cold car, and yet others with same heads, milder cams that are less wear prone, that know how to maintain and use the car have 50k+ trouble free miles with no signs of any wear when tested. Just goes back to anyone can kill a guide if they want too.

0Myhardtop

We do check.

And as of matter of fact, I was just on the Bat-Line with WCCH this afternoon to discuss this very thing.

As I recall, you like most of our customers are out romping the **** out of your set up - as you should, that is what it is for...but please, if not already, take the extra steps: change oil more frequent, allow oil to warm up before going Ricky Bobby and use a good quality oil. I like Mobil 1 0w/40.

17K miles with a semi-race set up is really good. And I know you're not driving like miss daisy either.

BTW, if you do have an issue, WCCH will stand behind it 100%!!!!

Thanks,
Carlos