[Tate]

How to find TDC using the drop valve method

Remove valve cover. Bar engine watching the rockers on the #6 cylinder. When the exhaust begins to close and intake is just cracking open, stop. That is close to TDC on exhaust, which means #1 is close to TDC on compression. Back engine up a bit. Install dial on intake valve, use lash adjuster to run the valve down 0.100" Bar engine forward until you deflect the dial a couple thou. I go to .002". Mark damper. Back the engine up a bit so you're not pressing against the valve. Adjust the rocker so the valve closes. Bar the engine well past TDC. Set the valve back down 0.100". Bar the engine backwards until you deflect the dial again to the amount you used before. Mark the damper. Measure the center of these marks, that is your TDC.

Don't do it on the exhaust stroke. At TDC, both valves are moving, which means your marks will be at different distances away from true TDC. It might not be out much, but why not do it properly when its only on revolution away? Likewise, this method requires no disassembly, only have to lash on valve to be back up and running.