Pizter

Not trolling. Interested in moving from the german platfom and its either a c6 z06 or a gen 2 V.

Only thing holding me somewhat back, even though I dont really care, is this stupid guide issue.

So. CNC ported ls3 heads on an ls7. Besides the port shape, why would it be retarded? How much power are you really going to gain over a set of cnc ported ls7 heads vs ls3 heads?

Every other day I get the ls3 grand sport talk. I don't want a grand sport.

Learn me knowledge pls.

Thanks.

c5racr1

Ported ls3 heads are a good option, you will need a intake manifold also.

AzDave47

I don't know about the LS3 head transplant, but having the LS7 heads redone by a quality shop is $1400 plus install or another $600-800 more with CNC work if you don't spend big $$ on valves.

I recently had my LS7 heads done and wanted to keep it lightweight so sprung for Katech Ti/mo valves that are intended to work in CHE bronze guides. You could go SS intake/exhaust with dual springs if you don't intend to run it a lot of time at 7K RPM.

At 47K miles and 17 track days plus some other performance events, all my exhaust guides and 6 of 8 intake guides were out of spec, some by 2-3X the wear spec of .0037" I'm glad I got all new valves because I would not want to run valves that had been in out of spec guides (personal choice).

Pizter

both of the faster heads/cam/intake cars here were already having excessive wear. One was WCCH, and 1 set american racing.

So we figured I could just toss the ls7 heads and maybe sell them, and just use a set of CNC ported ls3 heads. Just wondering if this idea is just idiotic or not. I feel like this would be a way better option and almost cost the same.

Dan_the_C5_Man

To the OP - please explain in your own words what you feel the differences are between the LS3 heads and the LS7 heads, and how those changes will resolve the issues?

Pizter

What i've been told is the angle? Of how the valve sits in the head is really aggressive. Or something of that extent. I'm still trying to learn these motors and cars. I mean, if you want to explain to me why im 100% wrong please do it. I'm here to learn.

Pizter

I mean, do peoples re-worked ls3 heads have the same problem or?

Cman01

Do LS3 heads even fit on a LS7 block?

Coolant passages line up between the head and block?

Unreal

Yes, ls3 heads can go on. For what it cost, just fix the ls7 heads.

Dan_the_C5_Man

Not here to tell you how "wrong or right" you are, or pass judgement.

I will say that most of us on the CF (the ones with an engineering mindset anyway) have for the most part "figured out" the LS7 guide / valve issue, and how to correct it.

Most of those same members would most likely not trade their LS7 heads for an LS3 setup.

If you have first-hand details of "failed" or "out of spec after the fix" LS7 heads, we'd all like to learn more about them (build details, cam, springs, valves used, type of use (1/4 mile, road race, street driving, etc.).

With this information, we might provide better feedback to you on whether or not you should abandon your LS7 heads.

RamAir972003

Now after talking to someone on here who has switched over to ls3 head yes you can and u loose about 15 20 the most to wheels, the reason he is doing this is to see if there will be guide wear after he pulls these heads also but yes it can be done...

dapopa9

This is looking to possibly be a good option since even the "fixed" LS7 heads are having the same issue.

I'm also interested in hearing if anyone has experience with the LS3 heads. Guess maybe it should be asked over in the C6 section. Do the LS3 heads also typically have their own issues?

Michael_D

It can be done. Why in the world anyone would want to do it is beyond my comprehension.... The foundation of why the LS7 can make as much power as it can, is the freeking heads.... LS7 heads are vastly superior than any other LS platform. Just fix them and move on.

Fix the damn things. Don't run the OEM rockers on lifts in excess of 'about' .620", and you'll be find.

Dan_the_C5_Man

..This is what I suspect is the core issue with the OP's (or others) builds, but waiting for the response on the details to validate.

MyLS1Hauls

If you put LS3 heads on an LS7 short block, you had better check PTV clearance, as the stock pistons are flycut for the shallower LS7 valve angle. You're probably fine with a mild cam, but a larger one could result in contact.

I'd rather rebuild my heads every 25k miles than run LS3 heads, personally. I've only heard of a couple sets of "fixed" heads that wore out quickly, and they all had cams with lift over .650.

long_tall_texan

Here is a very good explanation of the LS7 heads/guides/valves issue.

http://www.corvetteactioncenter.com/...-engine18.html

After reading through all of this, as a mechanical engineer myself, I have decided to fix my LS7 stock heads. I'll have bronze guides put back in them, and stock valves. Then, when re-assembling, I'm going with a roller-tipped rocker arm. That seems to be the most likely way to ensure the lowest chance of the fixed heads having an increased guide wear issue. Just my 2 cents...

Pizter

Don't know the exact life on either car. 1 of them though seems like the cam was much too big.

I just felt like if this issue could be fixed for basically the same price, without the chance of dropping a valve, I'd sacrifice the little extra whp you'd get out of the ls7 heads vs the ls3 heads.

Looks like I still have a bit of research to do.

olddragger

Look hard--I did. Ended up sending my heads to AHP. It was a good decision.