i had my stock heads redone & had new springs installed good upto 550 lift - can i run a zz4 cam with 1.5 rockers and still have enough valve clearance? what is the max valve clearance with a 88 350? neother the heads or the block was decked.

 

If your block is still at stock deck height and the heads haven't been milled, you should have no trouble with the ZZ4 cam. It's .474 on the intake side, and .510 on the exhaust with 1.5 rockers.

 

what is the max i can go with a stock deck?

 

Impossible to say. There's too many variables.

The valves are at max lift when the piston is somewhere around halfway down in the bore. So, peak lift numbers tell you nothing; unless of course your peak lift is something like 2". That probably isn't a concern for most of us.

The usual point in the engine cycle where the valves come closest to the piston is at TDC at the "overlap" point (the other TDC event in a cylinder's cycle, besides the firing instance).

If you advance a cam (make all valve events earlier with respect to piston motion) the intake will open sooner, and therefore will be farther open when the piston reaches TDC. Meanwhile the exhaust will have closed more. So advancing a cam reduces clearance on the intake side and increases it on the exhaust. Retarding the cam does the opposite.

Similarly, reducing the lobe separation moves the exhaust event closer in the cycle to the intake event (reduces the number of degrees between them), has the same effect on exhaust clearance as retarding the cam, since the exhaust event occurs "before" the intake event, and therefore reducing their separation means the exhaust valve events occur later.

Virtually any cam you would ever use that would also fit under .550" max lift springs, will not have any of these issues. You don't typically run into problems with that until you have something like 280° of .050" duration, and in excess of .650" of lift. Think "big race-only solid roller". It's not a question of "shouldn't" have problems, it's "it won't", with a street cam. The factory puts ZZ4s together on an assembly line, and has no problems. You won't either. About the only time you might, is if you run domed pistons and large valves, and the valve relief in the piston is too small diameter. Then, the edge of the valve might maybe hang the edge of the valve relief. But you're NOWHERE NEAR that with that little bitty stock cam. Don't even worry about it.