I'm probably going to be swapping a ZZ4 cam in my L98, and I've read the suggestions regarding valve guide clearance, screw-in studs, and valve springs. I will be running ZZ4 springs, retainers, and keys.

The retainers, 12495492, appear to be the non-rotator style. Is this still correct for the exhaust valves?

The keys, 24503856, are designed for 11/32" valve stems. I may be wrong, but weren't some valve stems 5/16" in diameter? What size does the L98 have? I'd check that myself, but the heads are at the machine shop.

 

no gm v8 has 5/16 valve stems. i'd buy some springs from a source other than gm, but if you did a search you've already seen me say that on here.

 

Just to add...

AFAIK the L98 heads don't, nor have ever had exhaust rotators. I think they saved that honor for the 187, 191, and 193 POS "swirl port" heads.

 

And 416...

 

416's have the rotators, or the POS swirl ports?

 

Rotators.

At least mine did.

 

Thanks for the clarification on the rotators and valve stem sizes. Attached is a picture of the valvetrain. I haven't pulled the retainers, but the ones on the exhaust valves look just like the rotator-style on a set of swirl port heads that I have. What do you think?

Yep ede, I saw your recommendation about the valve springs in another post. I can't recall the reasoning behind not using GM's springs, though... didn't you say that they weren't made by GM or something?

 

Yup. M R Rotators.

Keep in mind that GM springs are from the lowest bidder, not the best manufacture. If I were to coil up some springs out of bailing wire and sell them to GM for .001¢ per 1000, then they'd buy mine.

 

TTT.

Sometimes this server bytes.