sharkthehunter77

My spies(whom are everywhere) may have uncovered some!!! But, corvette heads bump the compression up...way up from the stock L48 compression of like 8.1:1 or whatever. what has to be done to keep the block together afdter bolting on heds like that?

Ryan77

They should be ok, they're aluminum right? As long as it's not more that 10:1 compression, the stock bottom end should be ok, as long as it's in fairly good condition.

nunus79

Good find! What's the mileage on that engine? I could be way off, but isn't that the head that comes on ZZ4s?

Ken73

There's actually three version of "L98 heads" in existance. The '85 and '86 heads are the stock smog iron heads; 76cc chambers with 1.94"x1.50" valves. 462624 is the casting number I believe. Then there's the '87-'88 (? I can't remember) aluminum 58cc chamber, angle-plug heads (same valve sizes.) After '88, I believe they changed the exhaust ports to the "D" shape (which are raised .100" up.) The later heads are what are going in my '82, and I'm using the Dynomax ceramic coated headers. They should match up with the D-port exhaust just fine, and leave some area below for some anti-reversion effect.

If yours are the later style, they are the ones to get. On an L48 (8.5:1 compression) it should put it up around 9.5:1 or probably closer to 10:1 - you'll definitely want to switch out the cam to something a little beefier, because the L48 cam with 10:1 compression will create a very high DYNAMIC compression ratio that will cause terrible pinging...

Metal Wulf

those heads will rock on an L48 :smash:
get the XE262 cam as well :thumbs:

Smokehouse69

The D shaped port heads are the ZZ4 heads, they have no problem with 10-1 compression. That and a XE268 cam will rock!

dukvet76

I bought the 58cc Aluminum heads and am putting them on my stock block along with the XE242 cam shaft, edl 2101 intake and Dynomax Ceramacoat headers. The heads were upgraded with Pro-Flow Swirl Polished Stainless Valves, LT-1 Valve Springs, Chrome-Moly Retainers and screw in studs, Hardened Guide Plantes and Valve Locks. The block is being rebuilt with new Keith Black pistons et al. It should be done in a couple of weeks, and I'll let you know the progress.

Budman68

I run L-98 heads on my L-48 and the compression is around 9.5 to 1. No problems so far.