I know been asked a thousand times..(no search available yet)

but a quick yes or no would be great

starting my 355 build finally...will a zz4 cam work with stock heads?
heads have already been done.

thanks a bunch

 

You'll need to upgrade the springs if you have stock ones on the heads, and you'll also need to have a machine shop set them up to accomodate the lift of the ZZ4 cam. Stock heads only handle about .480 lift. The .510 exhaust lift of the ZZ4 is what requires the upgrades. There's a couple of ways to set up your heads for the extra lift. The machine shop can machine down the top of the valve guides to provide the retainer to guide clearance necessary for .510 lift, or they can use valve spring retainers that are offset +.050. In addition to the offset retainers, they usually put shims under the springs to keep the installed height of the spring correct with the offset retainers. My machinist used shims under the exhaust springs anyways since you should remove the stock valve rotators when upgrading springs. If your heads are already installed on your motor, and you don't want to remove them again, I'd suggest having the offset retainers installed. No matter which method you choose, make sure to upgrade to the appropriate springs if you're still using the stock ones. They won't cut it.