Quote:
Originally Posted by SC2150
The only way to know the proper legnth for proper preload is to slowley tighten the rocker down until the rocker tip is just touching the valve stem end (you can spin the pushrod when starting to slowly tighten until you feel resistance). Then your target preload is 50 thou from zero lash. That equals app 1/2 turn of the rocker pedestal bolt. The least I accept is 1/4 turn and the most 3/4 turn. so if you have a 7.40 pushrod and it takes 1 1/4 turns, you will need a 7.350 (I always go with custom legnths to get it exact).
There is no way to determine this ahead of time until you have your cam installed and measure for it. Any vendor telling you a certain cam needs a certain legnth push rod is just guessing. The guess may very well be close, but I choose to measure for the exact legnth needed.  |
Thanks for the feedback. This actually confuses me a little bit. When you say 1/4 is the least and 3/4 is the most turns you will accept, 1/4 or 3/4 turns to what. My understanding is the rocker pedestal bolt gets torqued down to 22-26ft/lbs and the preload is determined by the pushrod length. The way I am reading what you wrote is somehow the threading down of the pedestal bolt is where the preload comes from. I know it would probably take 15 seconds for you to show me what you mean but I am having a hard time visualizing it. Am I wrong to torque the pedestal bolt down to spec and continue to adjust the adjustable pushrod until the rocker tip makes contact with the stem tip?