If you use rocker ratio method: I have 2 gutted hydraulic lifters pressed together with an aluminum rod in center (top to top). Make sure you surface the upper lifter flat, then put my dial indicator (with extension) onto the second lifter face to degree cams. Makes a nice big indicator surface...
Sounds like I should try to duplicate the same x-sectional area open when the ports and skirt holes aline in reguard to piston position or travel. I can measure this with a degree wheel indexed to TDC and calculate the piston position at a few different points such as when initial port to skirt...
In rebuilding a Mercury Sportjet with Force 90hp stroke I used Wiesco forged pistons but they do not have the 2 large diameter (approx 1") holes on the pistons intake skirt as the originals had. Wiesco claimed they are not needed in reguard to power and were intended for reducing piston weight...
