lowace

I'm having a little problem figureing out what fits what. I know "centerbolt" heads came out in 87 but, what were the alumnium heads on the late 86 convertables.What is the difference between the 86 and 87? Would the "centerbolt"s fit on my 86 coupe? Are intake and exhuast manifolds interchangable or do I have to stay with the old style aftermarket heads? I really would like to upgrade the heads and still keep within my budget the wife caught me buying "MORE PARTS" " "

vader86

well the intake is exchangable but why would you want it? , as for the heads, the 86 verts all had aluminum heads, and as far as i know (i was stupid and didnt know my car had cast iron when i bought it) the 86 aluminum heads are the same ones that are used on the 87, i'm sure Scorp will chime in somewhere on that. I believe the 86 aluminums had center bolt covers on them. If so, i dont see why the exhaust manifolds wouldnt be interchangable.

If your car has cast iron heads, they arent interchangeable, they redesigned it in the middle of production. But the intake still is-but again why would you want it. If you do have the iron heads, then look for some good aftermarket ones that allow for some porting.

Aggravated4life

My 86 Coupe has the factory aluminum heads..this wasnt exclusive to just the convertibles late in the year.I was one of the lucky 86 coupe buyers..didnt realize what I had until after I bought it.
:)

86-91 aluminum heads will work on your engine.

However,86-87 heads were a little different then the 88-91 heads.in 88,GM did some port work and cut back the exhaust valve,reshaping the exhasut port to a "D" shaped one.Thats where the name D port heads came from on these cars.
But dimension wise, theyre all pretty much the same.I would believe the 88-91 heads will flow a little better then the 86-87 heads.

Just for info,The ZZ4 engines uses the aluminum L98 D port heads that were on the 88-91 Vettes.

Btw,to upgrade to a stock L98 aluminum head isnt worth the money,unless its CNC fully ported.You wont see any signficant power gains by leaving them stock.

Youre better off getting new Hi flow cast iron heads with 2.02 valves and they dont cost an arm or leg.Maybe Dart or world products.
If you must have the aluminum ones,consider brodix or AFR heads.They flow very well out of the box,yet are somewhat pricey.
:)

lowace

So your saying 87-91 heads will boltup to my 86 intake?Ikeep hearing something about bolt angle being different.I really would like to use the later "centerbolt"s on my stoke intake and then step up to a ram jet next year.