Jack, either tool will work. To be sure of your measurements, use the same TFS checker tools used in the demo since the sample calcs are for those specific checker tools. These tools are inexpensive. The one criticism I have of the video is the addition of 0.075" for preload. It is correct to add length for preload but 0.075 that value is not for all lifters. Add the preload value for the hydraulic lifter you are using. Most short travel hyd lifters have a preload range of 0.020 to 0.060. Many builders add 0.050 for short travel hyd lifters. Verify your LS hyd lifter desired (optimum) preload add use that in the calculation. Note: It may be 0.075 actually since that sounds like an LS preload but check it out yourself.

Agreed about preload. It's also different if you have an all iron block head -iron with aluminum head- or all aluminum block and head engine. The latter being the largest preload for thermal expansion is the largest in aluminium. I have a 97 Camaro with iron block and aluminum heads. Gen 2 LT1. Preload is approximately .030- .035 with either morel lifters or the Lunatis I have.

@@clifford_2zero7 Yes, good point. As an example, Howard Cams ALWAYS publishes recommended pre-load for there lifters. Their common SBF hyd roller lifter is 0.030-0.035 with a cast iron block and AL heads. Different values for different block/head material combos.

Mike, the 0.017 is a standard machinist calculation for a 5/16 ball pushrod. What is going here is that the pushrod's ball radius, not the oil hole flat surface, is what touches the lifter and rocker. What you measure is the overall length which is where the calipers touch the machined off flat areas of the pushrod oil through holes. In the video, they simplified by showing an example of a pushrod that is 8.01668 (8.017) for overall length, then they subtracted that from the 8.00 value which is the length at gauge diameter for 5/16 ball end pushrods. The difference is 0.017. The example may be confusing because not all pushrods are 8.01668 (8.017) for overall length, but they were trying to show a simple example. It will always be ~0.017 for a 5/16 ball end pushrod regardless of actual overall length. They should have clarified. TFS also cites 0.017 in their instructions for their pushrod length checker in the video. See their instructions at static.trickflow.com/global/images/instructions/tfs-9000_at.pdf

Brandon In the illustration shown the .017” at one end of the push rod ball. If that were correct you would have to account for both ends or .017”x2 or .034. Maybe that is confusing people.

@@brianf8621 Yes Brian. You bring up a good point. I think the 0.017 is the total length to subtract i.e. 0.0085x2 for both ends of the pushrod combined. I note that the TFS instructions also cite 0.017.