Corvette0096

Do they have the same bolt pattern as my 85 heads? Where all my A\C bracket and stuff bolts up........

Jim85IROC

Yes. The ZZ4 uses Corvette aluminum heads.

tommelton

Same accessory bolt holes, but they are centerbolt style for the valve covers, not the perimeter style as on the 85.

Tom Melton
82 CE
86 Z51 Coupe with ZZ4 and ZF6

Corvette0096

That is what I wanted to hear.....But there is some Egr issues?

jburnett

You'll also need to slot the base manifold's bolt holes as the aluminum head's mounting holes are slightly higher; but, that's really the only diff.
-Jeb Burnett

JAKE

Hey, Jeb: Good to see you here.

I was wondering how about the Vortec heads that so many guys ask about. I know that slotting the intake manifold bolt holes is needed to allow the manifold to boltup but does this effect the port alignment.

You outta see the problems we've been having trying to get a TPIS Miniram to bolt up to set of Brodix 15 degree heads. I mean NOTHING aligns, not intake port, water ports, bolt holes, and the end gaps are so big you can put your index finger in it.

Thanks,

Jake

Jake

jburnett

Umm...Yeah, I can imagine you're having a problem. A customer wanted to use a set of 15 degree Pro Action heads on his 434 with a MiniRam. I mocked everything up and told him that I was going to have to cut the flange off the runners, rework everything and then have my welder TIG it back together; it was gonna be expensive. Instead I got him a Pro Action single plane manifold and welded EFI bungs in it!! Much nicer, much easier, and MUCH CHEAPER!! The Vortecs are a totally different animal than the ZZ4's BTW. They have a completely different bolt angle than any other SBC head, they're verticle. You actually either have to buy a specific manifold for em (Scoggin is now selling a big-mouth TPI base for the Vortecs) or weld up the holes and re-drill... PITA!!! Really the only diff between the aluminum heads and the old 882's that were used on the early TPI's is the angle of the hole; a lot of aftermarket base manifolds already come with the elongated holes to fit both later aluminum heads and early (pre-86) applications.
-Jeb Burnett
PS- Good to see you here too, Jake!!

JAKE

Yep, Jeb, that's what had to be done for a 434 I'm doing. Thankfully all this is way outside my area of expertise; Bob Jones' has had the headache with this mod.

That manifold has been cut open so many times and re-welded that it's a wonder it's still able to hang together.

First it was to port it to remove the turbulance that set in at just over 320 CFM; then it became a matter of improving the flow even more so that it didn't present a restriction to the heads, which flowed over 340.

Then came the angle problem with the bolt hole mismatch.

So the manifold got shipped to us from CA for me to mock up and the water ports weren't even close to covering the water ports in the heads, so back to CA they went.

Latest word is that all that's been fixed and the heads are due here anyday. The manifold is being held back for lots of photos and may be featured in one of the car mags.

What a nightmare, but at least all the bugs are out incase anyone needs those mods in the future.

Jake

18carfan

Didn't see this mentioned but the alum L98 heads never changed as far as intake bolt pattern goes. Only the iron head L98 motors (F-bdy) changed on the center intake bolts. An iron head Vette L98 intake will bolt right up to a ZZ4 (L98 alum) head. The EGR problem mentioned above becomes obvious when you realize the ZZ4 heads have no EGR ports. Just wanted to drop that in here. -Jeff

rafzz4

ZZ4 uses the center style bolts....at least mine does :crazy:


[Modified by rafzz4, 8:37 PM 4/3/2002]

Corvette0096

Rafzz4, The heads in the pic are center bolt style!

rafzz4

Thanks I was totally spacing there. I am glad at least someone has looked at my pictures at least!!! It seems like there is no interest in my car at all. Makes me wonder what is wrong..