Well, not much else to do but start from the beginning, otherwise you are just shooting in the dark and trying to hit the problem. The fact you are making contact with valves and pistons will require heads to come back off and be dis-assembled. You will have to check valves and pushrods for being bent. While you are in it, you can easily check the guides with a ball gauge and micrometer. Then check installed height's on the valves and set the installed spring pressures with shims. To check your valve to piston clearance it can be done several ways, here is what I do to get a feel for what is going on.
Install one intake and exhaust with light checking springs, ones you can easily push open by hand. Use your old head gasket, set the head on the block and snug it down with a couple of bolts. Rotate the piston to TDC, with a dial indicator on the valve stem push the valve open until it makes contact, check the dial indicator for the total movement. Now this will NOT be how the engine will ever be while running, it will be just a basic check. In this position the piston will be the closest it could ever be to the valves, if it passes this test you will not have to do any more checking. Take the max lift of the cam lobe, found on the card that came with the cam, and multiply by the rocker arm ratio, 1.75 I believe is the stock arm ratio, but check that. So now you have the total lift, add a margin of error to this. Everyone has their own figure, I believe Reher Morrison uses .120 exhaust and .100 intake. Most others will use a smaller #. Add that to your total lift figure, compare it to the dial indicator # you got. If you have more you are good to go. I suspect it will be less. So if less, then the procedure will change and now you have to do the checking with actual piston and valve positioning for a running motor. Typically done between 10 deg. before and 10 deg. after TDC. With actual cam lift #'s at these settings.
Not hard to do, but a little more involved.
So we can assume your numbers will be too small, now how to correct it? Cam with less lift, change relation of cam to crank, rockers with less ratio, thicker head gasket, cut reliefs in piston tops. Decisions, decisions, ahhh life of an engine builder. COMPROMISE'S.
As far as those stock rockers go, they must be perfectly flat on the contact surface to the valve stem. Used ones typically are not, new aftermarket ones have potential of having other problems also, ratio differences, prone to breaking with higher than stock spring pressures, which you have now if using recommended springs for that cam.
Install one intake and exhaust with light checking springs, ones you can easily push open by hand. Use your old head gasket, set the head on the block and snug it down with a couple of bolts. Rotate the piston to TDC, with a dial indicator on the valve stem push the valve open until it makes contact, check the dial indicator for the total movement. Now this will NOT be how the engine will ever be while running, it will be just a basic check. In this position the piston will be the closest it could ever be to the valves, if it passes this test you will not have to do any more checking. Take the max lift of the cam lobe, found on the card that came with the cam, and multiply by the rocker arm ratio, 1.75 I believe is the stock arm ratio, but check that. So now you have the total lift, add a margin of error to this. Everyone has their own figure, I believe Reher Morrison uses .120 exhaust and .100 intake. Most others will use a smaller #. Add that to your total lift figure, compare it to the dial indicator # you got. If you have more you are good to go. I suspect it will be less. So if less, then the procedure will change and now you have to do the checking with actual piston and valve positioning for a running motor. Typically done between 10 deg. before and 10 deg. after TDC. With actual cam lift #'s at these settings.
Not hard to do, but a little more involved.
So we can assume your numbers will be too small, now how to correct it? Cam with less lift, change relation of cam to crank, rockers with less ratio, thicker head gasket, cut reliefs in piston tops. Decisions, decisions, ahhh life of an engine builder. COMPROMISE'S.
As far as those stock rockers go, they must be perfectly flat on the contact surface to the valve stem. Used ones typically are not, new aftermarket ones have potential of having other problems also, ratio differences, prone to breaking with higher than stock spring pressures, which you have now if using recommended springs for that cam.
