Nice work buddy. I am doing the same procedure on my 393W. I’ve been frustrated by the dial indicator method to verify preload for the reasons you cite. I have used blue tape on the pushrod with a straight edge across the valve cover mating surface intersecting the pushrod. I use a razor blade to make a mark on the tape and then measure the distance plunged from that mark. Kinda crude with the razor and frustrating with the dial indicator, so for preload, I use the industry standard formula: Lifter Preload = Distance per polylock turn / Rocker Ratio + Distance per polylock turn. I will provide an example using a typical 3/8 rocker stud with 24 TPI and a typical 1.6 roller rocker. One full turn on the polylock will move the pushrod down 1/24 or 0.0417. Distance per Polylock Turn / Rocker ratio = 0.0417/1.6 = 0.0260. Now per the formula, you add 0.0417 + 0.0260 = 0.0677 which is the actual preload i.e., the distance the plunger moved down. Comp cams loves to cite liter preload as 0.5 turns after zero lash, so that would be 0.5/24 or 0.0208. So, 0.0208/1.6 = 0.0130. Now per the formula, you add 0.0208 + 0.0130 = 0.0339 which is the actual preload. One thing that has always bugged me is what lifter preload to use with the standard Ford Motorsport 302/351 hyd roller lifter FMS-M-6500-R302. There is no published value for this (trust me, I’ve looked). Which lifter are you using and where did you get the 0.025 preload value? Per the formula above, I note that 0.025 actual preload with a 3/8 stud and 1.6 rocker is about 1/3rd turn on the polylock (0.37) past zero lash. For contrast, recently I was looking at the Howard cams SBF hyd roller lifter which spec’d 0.030-0.035 for cast iron block and AL heads. 0.025 seems a little on the low side, so just curious. Real car guys do math and measure things. Fake car guys copy/paste from blogs! Keep the good work!👨🎓
the .025" was the starting point that I wanted to try, the least amount of preload I can run the better, (to an extent) to avoid random lifter pump up during high rpms
That's a pretty good method, getting the measurement with the lifter collapsed, assuming you know all your numbers, I have new lifter and have not been pumped defenatly using this method this weekend to find out my pushrod length, thanks for the video
Video is a year old, but just came into my feed. Issue I see is that you're setting rocker geometry by adjusting pushrod length. That is incorrect. You need to set rocker geometry, pushrod length is a result of that. There is a good video out by Scott Foxwell on how this is correctly done.