What pistons should I use with 89 heads off a corvette. They are angled plugs. Springs have been changed and I plan on running ZZ4 cam. I don't want some huge compression ratio. 10 to 1 max. What about disn pistons I hear you get a good burn with this combo.Also are torc specs the same with these heads as my stock 89 l98 cast heads? What about head gaskets? Should I buy new head bolts?

 

If you dont want killer compression go with stock replacement pistons, dished 4vr pistons. The old head bolts are normally fine and you should use a quality head gasket set, like nitro seal. I beleive the standard nitro's are 0.45 thick so that will also help keep the compression lower. I'm not sure about the tq specs for the aluminum heads but im sure the specs are different.
Good Luck!
SSC

 

Your final compression ratio depends on several factors.
But on a
.030" over 350 if you use the recommended corvette
head gasket (.051" thick) and flat top pistons (.025" down in the bore) your cr would be 10.22:1. Would be ok on 93-94 octane.
GM also recommends hardened headbolt washers. You can get them at any GM dealer.

 

Should I buy corvette head gaskets? Both my car and the heads are 1989. Is my block the same as the corvette? Do I use corvette torc specs for the heads and intake? thanks.

 

1. Yes 2. Don't know,doesn't matter 3. Sure don't forget the headbolt washers. .... Your welcome

 

1. Use Fel-Pro part # 1014.

2. Those blocks are the same no matter which sheet metal (or fiberglass) they came wrapped in from the factory. A casting is a casting.

3. You could also use ARP or other high-quality hardware, just make sure it's bolts with washers. You don't want the bolt head grinding against the aluminum. Torque is the same as for cast-iron heads, I use 60-65 ft-lbs, tighten in 20 ft-lb increments, go around the heads at least one full time after they reach 60 to make sure none are loose, always check torque while the bolt is turning. DO NOT OVERTIGHTEN THEM, that is the worst thing you can do, it is certain death to the head gasket. Use Loctite PST thread sealer with Teflon on the threads, or Permatex 300 (brown gooey glop), DO NOT use silicone.

 

Thanks Guy. I was a mustang man at one time then I grew up and bought a bird. Had an 87 GT and broke down all the time not to mention you could not go around a corner with the thing.Traded it for a 1990 5.7 formula and the rest is history. Current project 89 GTA. I love it!!!!!!!!!!