If I got some Alum. vette heads for my 89' L98, what is involved in porting them and how much should that cost? Will any 86-92 model L98 heads fit?

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Gunmetal 89GTA T-Tops L98
Gettin there's all the fun
Best 60 ft: 1.996'
Best 1/8th mile: 9.02 @ 76.5mph with 60' time of 2.14
Mods: air filter, hypertech chip, 3" exhaust

 

unless you want a set of alum. vette heads specifically... why dont you go for a set of vortec heads? from what i hear, they will cost less(providing you port the vette heads) and produce more power. given, they are iron, but hey, power is power

 

Vortec heads wont fit on a TPI intake manifold thats why. The bolt patterns is completely different and the intake ports dont line up.

You can get the Corvette heads, I did. But they have a different bolt pattern too. You can solve that by getting an aftermarket intake manifold like from Edelbrock, Accel, or TPIS. Or you can enlarge the middle four holes on the intake manifold to line up with the Corvette heads. Dont forget the Corvette heads do not have EGR passages in them, so you wont pass smog if you have that in your area, and the smog tech checks the function of your EGR. I'm getting around that by setting up my EGR like the Corvettes do, with a tube off the #8 exhaust port up to the passage on the back of my TPIS intake. (all aftermarket intakes have this)
You can get the heads from any GMPP dealer as ZZ4 heads.

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What about clearance? Don't you orginally have 76cc heads, and your trying to put on 58cc Vette heads. Wont the valves hit? Not to mention the compression ratio would be REALLY high.

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Rob
'86 TA 305 TPI
Gutted MAF
Ported Plenum
TB Bypass

 

should be no clearance problems or compression problems. This is a stock head that comes on a 350 already. You would probably be hitting your valve guides way before you'd get a piston clearance problem... unless the cam timing was off.

Sears has a decent electric grinder that's good for porting. Look at some ported heads closely to get the idea.
good luck

 

Uhh.... f-body L98 heads are 64cc, not 76cc. I computed my compression ratio out to 10.3:1 with these Corvette heads. It works fine on 92 octane premium. But I have to use 100 octane at the track or I get knocks and pings.