OK, trying to get all my ducks in a row here. Tell me if I've got my facts straight, and then lemme know If I've missed anything.

To put AL vette heads on the ole l98, this is what I need...I think.

My current manifold will need to be machined to fit the bolt patern of the heads, right?

There is no accomodations for EGR, so what are my options?

The edelbrock TES will bolt right up, correct?

I'll need special gaskets to go between the iron block and the aluminum heads right? ...since they're diff. metals, right?

What should I be concerned with considering the smaller combustion chambers? This will raise compression right? How will this effect my performance? Let's assume that the only major mods on the motor are headers, and a mild cam. Maybe some minor head work...ie, valve job,rr's etc.

Did I miss anything?

 

yup thats about right. when you go for head gaskets they will or should ask you iron or alluminum so thats a nill point. the vette heads use an external egr passage not internal like the irons. if you get an edelbrock or other manifold it will have provisions for external egr and dual bolt patterns. the compression ratio will raise by 1.0 points roughly to 10.5:1. lastly the headers should still work pretty well.:lala:

 

What will the comp. ratio do to performance?

Can I use my old manifold....althought I can see why you might as well replace it while it's off.

 

you can use it just elongate the center holes and use a felpro 1204 which has the egr blocked any since the heads dont have the port. the compression ratio will give you a bit more power but the head flow in more important and a good cam.

 

Your compression ratio will increase roughly .6(1cc of volume=.1 in compression/64cc to 58cc). Keep in mind that if you go over like .470 in. lift or so the valves have a tendency to smash into the cylinder wall(not a good thing). I had my egr turned off in my old car(still passed emissions,still there just for looks though). Get an egr block off plate if you are using the vette intake or just leave the egr on the original intake and elongate the two center intake bolt holes.

 

oh and if you do use the stock intake base do yourself a favor and at least port that sucker. the stock intake system will be holding you back more then stock vette heads will or even a stock cam.

 

Over .470 lift the valves smash into the cylinder wall? I don't see that happening. I'm actually running over .480 lift myself with the same heads.. have a friend over .520. Make sure you get head bolts with washers. These heads come with guideplates, so either take them out or buy non self aligning rockers and hardened pushrods.

 

maybe thats on a 305?

 

I ran over .510 lift on those heads on a 350 with no problem. Most likely thinking of a 305.
To the question, TES bolt right up fine.
Compression will be roughly 10:1 with factory pistons and standard head gasket. more with a thinner gasket.

 

One of the accessory bolt holes is missing from the passenger side head. You'll want that hole in there to mount the bracket to. Just needs to be drilled+tapped.

 

So you can use the stock rockers with guideplates IF you have hardened push rods correct?

And if you block off the egr opening on the intake it will still run fine?

 

I figured I go with roller rockers since I'm in there anyway.

Yeah, what's the deal with the EGR? The car should run fine I would imagine, but you'd see a code....is it 32? Other than maybe not passing emissions, that should be it right?

 

Upgrading an F-Body L98 from iron L98 heads to Corvette aluminum L98 heads will in essence give you a Corvette L98 which has the compression 10:1. You will have to run an external EGR just like the vettes do.

The reason the power ratings are different between the F-Body L98 and the Corvette L98 are due to the heads (flow and compression), exhaust, and simply becuase GM would never admit that the FBody has as much power as the big brother vette.

With the upgrade to aluminum L98 heads will essentially yield L98 Corvette mph's in the 1/4 but not necesarily the same ET (the Corvette suspension and therefore hookup is better).

An upgrade to a ZZ4 cam after that would give you a ZZ4 motor which is rated at 355hp/405tq. The ZZ4 cam is a fairly mild cam in relation to drag cars and has emissions passing capabilites in proper tune but can produce pretty decent power! This shows that these heads (for stock) have excellent potential and even better if ported out with a 3angle valve job.

My L98 is getting tired so I chose to buy a ZZ4 crate motor rather than upgrading the heads and cam because I need a 0 mile motor.

 

Kevin91z on here is running vette heads and the LT4 hotcam. Pretty sure he has 1.6's putting the lift at .525" I'm running STOCK iron heads on my 350 w/ .525" lift and have no problems, and don't expect any if I switch to vette 58cc heads.


QUESTIONS:
1) Can you run hardened pushrods and self aligning 1.6's with the vette heads and their factory guideplates???
2) Are all vette heas the old intake style bolt pattern?
3) They're still 1.94/1.50 valves aren't they??


THANKS!

 

1) you dont need guide plates if you run self aligning rockers.
2) vette heads have the old intake pattern yes, edelbrock and other aftermarket intake manifold have a dual pattern, new and old.
3) yes they are 1.94/1.50

 

I should've stated that. I dont know where in the world I got the assumption he was using a 305 from. Must be the medication. Yes you are right on a 350 there is no problem with that much lift. On a 305 since the space between each chamber is larger,it moves them closer to the walls. Sorry for not clarifying..

 

I was under the assumption that the vette heads HAD FACTORY guideplates on them? Thats why I was asking if we could go ahead and use our self-aligning rockers with hardened pushrods, etc. Some of the above replies hadn't made that clear.
THANKS guys!

 

mine didnt come with guide plates but they where pulled off a zz4 engine at the time.

 

Mine have factory guide plates and screw in studs.

 

screw in studs no plates here. fresh no miles.

 

Thanks guys for all this info. Any ideas on where to find a reasonable set???

 

EBAY theres a ton of them on there all the time. search vette and zz4 heads. cams on there all the time to for zz4's.

if you search zz3/4 heads you will find them for lower prices typically then vette. got mine for $400 for both shipped brand new in the box. then again i got a brand new zz9 cam for $225 shipped in the box with cam card and all. :hail:

 

1. I would seriously advise ditching the stock guideplates, if thats what you have. They are not hardened, and a hardened pushrod can, over time, damage the guideplate.
2. Yep. And centerbolt valve covers.
3. Yep.

Blocking off the EGR... well... it all depends on the chip. I've tried both 88 and 89 chips totally stock with only the VATS turned off (not EGR related) and neither one set a code without the EGR hooked up. MAF cars, IMO, tend not to set code 32's if the EGR isn't there. An EGR solenoid problem will set it, and a stuck open EGR will set it, but my experience has been that a missing EGR will not. Other people have had problems setting a code doing the same thing, why I dont know. I'd say the error check is finicky and inconsistent. If you have SD, I'd say a code is guaranteed.

All have screw in studs. The ones I have seen are all helicoiled as well.

 

Man, you guys kick butt!:hail:

ZZ3 and ZZ4 heads are the same as the l98 vette heads? Are there any differences at all? I bet that the name "vette" adds a lot to the price

Once again, thanks for all the help...maybe we can get a vette head questions "sticky".

 

Gm used the non hardened guide plates only to hold the pushrods in place on the assembly line. the rockers are what centers the pushrod.
I made the mistake and used the stock guideplates (thinking they were hardened) with non self centering rockers and hardened pushrods. I was lucky not too have a problem.

 

All '87 vette heads use hardened guide plates as these were the last year of the non-guided rocker arms in '88 they went to the guided rocker arms they did have guide plates but they are not hardened on the later years and are only there to ease the assembly of the motor. I got a set of '87 w/ new $100 roller tip rockers with the hardened guideplates for sale in the classifieds.

 

No, I'm using 1.52 roller rockers, making my lift .498".

1) No, you DO NOT want to use self-aligning rockers and guideplates. Use one or the other but not both.
2) Yes
3) Yes

 

Why aren't you using 1.6's?????? Just curious!


Also, so you can just use old school rocker arms and guideplates on the vette heads??? Thats cool. Thansk Kevin!

 

You can only do this with modifications to the valve stem height. Do not attempt to swap the rocker arms on the stock 88+ heads to the non guided rockers. The 87 heads are set up for non guided rocker arms.

 

You can only do it with modifications to the valve stem height? No, dont think so.
I'm running roller tip rockers (not self aligning) and guidplates. No problems.

 

Well let me qoute John Lingenfelter:
"The rail rocker requires a taller valve stem tip that protrudes further above the retainer. This is important since rail rockers cannot be used on older, shorter valves stem engines."

:lala:

 

Well, let me quote the original question, rather than running off on a tangent:

"Also, so you can just use old school rocker arms and guideplates on the vette heads??? Thats cool. Thansk Kevin!"

Yes, you can use old school non self aligning rockers on vette heads (with taller valve stems) without issues.

 

I had a set of 1.52 roller rockers, and 1.65 roller rockers. The 1.65's would make the lift .541", and I would have to get new springs and have the heads machined for the larger springs. So I used the 1.52 rockers and saved the extra expense.

 

Thanks man. What brand makes 1.65's?? I thought mine were just 1.60?!?! Should've used some TPIS ZZ9 springs.... stock diameter up to .550" lift. Only $125 and use stock retainers and stuff. Later!

 

I believe Harland Sharp rockers are available in a 1.65 ratio. I suspect that Comp Cams might have some as well. Thats the run of the mill stuff, expensive stuff left aside. With enough money you can have whatever you want, you know.

 

When running the LT4 Hot cam you need new springs too right?

 

Does anyone make headers that fit a 3rd gen and have the ext EGR hookup?

 

Um, If you buy a set of heads...Wouldnt they come with guideplates and pushrods already? why worry about whether they are hardened or not? But, I Dont think the car will run good without EGR because of the computer...It is tuned to use the EGR...and it makes calibrations and measurements with it...U need to have it tuned or something to take off EGR with no problems... Unless you go to carb and GIVE me the TPI System..LOL

 

Nope, you have to modify it yourself. Only L98 Corvettes and Vortec trucks come with an external EGR setup like this, that I know of...

 

Think I found a set of these heads locally... CHEAP! Is it worth putting 2.02/1.60 valves in them? I plan on having a friend port/polish these to the extreme. He is very good with heads. Any opinions?? THX!

 

Thats what I thought. Thanks. I've been combing through the exaust board and I guess I'm mod up a set of TES's and coat them.

 

Yes,I think a corvette heads sticky is a great idea!
My vette heads also have the guideplates(whats up with that)
And,I'm planning on running the CRANE #104225 on my sd setup w/ a 2000stall.
Any objections or better advice????
thanks for any helpful input,Tim