piston to valve clearance

[Rev]

The best and most accurate way to get piston/valve clearance is to install very light springs on the #1 cylinder valves. Mount the head using the old compressed gasket torqued to 25 lb/ft or so. Put the #1 piston at TDC at the end of the exhaust stroke/ beginning of the intake stroke. Put a dial indicater on top of the spring retainer and push the valve down with your finger until it hits the piston. Do this a few degrees before and after top dead center. As mentioned earlier, use a solid lifter for this measurment set with 0 lash. Record how much further you can depress the valve after it's opened by the cam. That's the piston valve clearance. Do the same thing for the exhaust valve.

I had the machine shop install the weak testing springs which I borrowed from them. I went home and did the test and then came back to them for reinstallation of the real springs. As Gearhead said, you will want .100" clearance. My machine shop guru insisted that I do it that way instead of the modeling clay technique. He said "yeah, it's great if you have a whole lot of extra clearance, but what if it's close? How accurately can you mic that piece of modeling clay?"

Rev