Well since I'm not getting any help in the TBI board I'll post this here too.

I've been pondering on just saying the hell with doing any work to my "187"s and just slapping in my ZZ4's to get a feel for them but I have a list of questions for those in the know.


1. Will I lose some bottom end "streetable" torque by switching these heads. They have been 3 angled, bowl blended, valves backcut, milled down quite abit and the combustion chambers are polished smooth.

2. What is a good head gasket to use? from what the machinist told me he milled them down .030 but I know they have been milled a touch before I got them. I want to get a good quench area and to maintain good compression. If I could get between 9.8 to 1 to 10.5 to 1 and be able to still run premium I'll be happy. I CC'd my heads today and they came up to 55cc.

3. There obviously will be alittle overhang from the heads as they are built for a 4 inch bore. will this cause a decrease in effiency (spl?) Will this cause any problems?

4. how much of the 2 middle intake holes will I have to grind away to be able to bolt the intake down? will this cause any leaks?


5. I know these heads normally use guideplates. With self aligning rockers will I still need these? (the heads don't have them on)


I have most of the parts I need to do this but I'm just missing head gaskets to get this done. Some help would be greatly appreciated.

 

wow, I must ask the really hard questions. Do we have anybody here that can give me a hand?

 

Screw it I went with 10105117 .028" - 4.00 bore gasket from scoggin-dickey

 

You bought the right gaskets- I was going to recommend them to you.

The only other question I can help you with is the rocker arms. You MIGHT be able to use the self-aligning rockers. Make sure the self-aligning "legs" on the underside of the rocker arm pallet area don't push on the retainer. You want it ONLY to push on the valve stem tip and nothing else. If they touch, you need to go with standard rockers, guideplates and hardened pushrods. If they DON'T touch, you're good to go with the self-aligning rockers, no guideplates and standard pushrods.

 

thank you for your help. Anybody else?

 

1. The ZZ4 heads are better than your stock iron heads, but not by much. You wont lose anything.

2. Question answered by Damon, but you will need to do the math to make sure your compression is still 10.5:1 or less.

3. I have not read about any problems like that on this board.

4. Quite a lot. Do some searches as I remember seeing pics.

5. I've been told you must use guideplates and non self-aligning rocker arms with these heads. I've never tried them any other way. Damon seems to be on the right track.

Also search this board and the TPI board for "corvette heads" or "l98 aluminum heads" or similar for the other concerns you'll have with these heads. You've already touched on one with the intake manifold bolts being different angles. The other is the lack of EGR passages, and the third is the missing accessory bolt hole for the serpentine setup.

 

I looked these heads up on SDPC and these are the new casting ZZ4 heads. It says that I HAVE to use my self aligning rockers. Also my heads have all the standard accessory holes.

 

This is a good thread, as I'm also looking to get the 463 castings for my 305. I'd be cautious with statements such as "all the standard accessory..", that doesn't mean it covers the serpentine arrangement. I'll have to do some searching around.

 

I have a set of the new zz4 castings 113 heads and we went with guidplates.A friend of mine had trouble with his self ligning rockers on his vette.These were the production 113`s though.Plus guidplates just seemed the best way to go.I dont know why they would say you have to use the self aligning rockers.I didnt.We did have to have them machined for guidplates.Bought mine new from gmpp same part number and same heads as on the zz4.Its a revised casting.Better than the production heads.you can run guidplates.I would agree with the head gasket as well.

 

This is from www.sdparts.com

"This GM Performance Parts SB Chevy Aluminum Cylinder Head was used in 1987-91 Corvettes with TPI. They have a standard carbureted intake bolt pattern and centerbolt valve covers. Ideal for use in street rods and fresh water boats. Must use self aligning rocker arms. Priced per head."

So I guess I should be ok with my regular rockers then? I already have 1.6 SA comp cam roller tip rockers.

 

I wasnt saying you cant use your self aligning rockers just sayin you can use guide plates as I did.Just a personal preference.I did have to have the machined for guide plates.Thats prolly why they say that.