Stumbled across a set of stock ZZ-4 heads, part # 12556463, 1.94" intake, 1.50" exhaust, 58cc chamber aluminum heads, screw in studs and stock springs from the zz4.

Did a couple searches on them and they appear to be a bolt-on for my 89 IROC 250/700R4 TPI.

Can anyone confirm that they are/are not a direct bolt on for my engine?

Would the stock springs hold up for the cam I have if I also switched to the self aligning Crane 1.6 RR's?

TPIS ZZ9 cam (lift .520 ex/.484 in-- dur. 282 ex/270 in)

THANKS for any advice and info.
Craig

 

Opps, I guess they will not work unless you have an older style intake.

 

they should work cuz they are same heads as on the vettes. centerbolt covers i am pretty sure as well. so yeah, it should work fine. LOL

 

you will have to grind on the center bolt hole of your intake manifold a little, but nothing that cant be done in 10 minutes.

 

I have aluminum heads off a ZZ3 and they will work except as noted above (as they use the older angle for the centerbolts). Also, the heads do not support an EGR. You will need to look at setting up an external EGR similar to the Corvette.

I would change the springs.

 

Carefully check your valve retainer- valve seal clearance. You're nearing the limit if your heads are like mine. Knowing GM tolerances... safer to check it than find out the hard way. Might also need to drill an accessory bracket hole.

 

NO!!!!!!!!!!!!!!

YOU can't use those. They will NEVER FIT!!!!


Send them to ME!!!!!

 

Crap--the heads got sold!

Anyway--THANKS FOR THE REPLIES AND THE INFO--I REALLY APPREACIATE IT!!!

Some one educate me.

I assume from the responses that the ZZ-4 heads were from an earlier time period than the L98? (Sorry--guess I'm not up on my thirdgen history like I should be)

Would the L98 58CC alum heads be a direct bolt? What is the part # for those?

If, by the time U bought a set of the L98 heads --had all the work done (valve job--port/polish/CC--springs--Etc) it sounds like U would spend 1000.00/1200.00--wouldn't U be better off just getting a set of AFR's for a few hundred more, with all the same work?

The AFR's would be a better performance #'s/flow ETC--right?