I've heard +/- 2 degrees is acceptable when grinding a cam.

 

My site says .00416" is 1/2 a flat with 7/16-20 studs. Read carefully.

 

Missed that somehow. This post thoroughly confused me. I set mine and haven't had any problems. Then I read this and thought I screwed up.

 

You can use this formula to calibrate your rocker nut for lash:

(1/TPI)/6flats = inches per flat(hex nut)

TPI = Threads Per Inch

3/8-24 is 24 TPI, so (1/24)/6 = .00694 or ~.007 per flat on the nut.

7/16-20 is 20 TPI, so (1/20)/6 = .00833 or ~.008 per flat on the nut.

 

Another way to look at it for a 7/16-20 thread is there are 20 threads to the inch. So one full turn will equal .050". If you want .060" than you would need one full turn plus 1/5 of a turn. If you want .020" that would be 2/5 of a turn. Hope this helps.

 

I hate to bring up old threads, but this doesn't work accuratly. Since the pushrod sits back behind the stud, it gets depressed more than the center of the rocker arm, so one full turn is more than .050", I checked it with a dial indicator, it was aroud .080"

 

Unless you use a dial indicator to set all the valves (who is gonna do that ), the TPI the only real constant you can use. It's not that critical, in most cases. All a person has to do is find what preload that works best for them and be consistent with setting all the valves. I mean, if you took 5 people and had them find zero lash, you would probably have 5 diffferent actual values. So setting the preload based on that will result in 5 different actual preload values. Bottom line is there might not be enough difference in running to tell any of them apart.

If you want, just use your dial indicator to set up a baseline for how many turns equal whatever actual preload. I guess it may even be different for different ratio rockers.

OTOH, people have been using the TPI and number of turns method since hydraulic lifters were invented and it seems to work ok.

 

this makes sense for those w/ comp r failures who were using 3/8 studs...