valve adjustor nut, locking vs self lock

[Jerry G.]

Just doing the valve adjustment on the race car before Monterey and I'm currious. The stamped rocker manufacterer included self locking friction nuts to adjust lash. In the past I've used adjusting nuts with a set screw. Think kool nuts by Crane. In a racing application do we have any opinions on one design vs the other. it sure is easier to adjust the lash with the self locking. jerry

[Jim L.]

Re: valve adjustor nut, locking vs self lock

Jerry,

Some manufacturers of rocker studs, ARP comes to mind, recommend against the use of self locking nuts with their rocker studs.

I'd go with the PolyLoks, myself.

Jim

[Clem Z.]

Re: valve adjustor nut, locking vs self lock

back in the day we used self locking nuts BUT we used "PAL" nuts on top of them to make sure they did not move on race engines. the posi locks have one advantage they are tall enough to make the oil from the push rod hit them and run down onto the rocker ball. i have seen if you don't have the "drippers" in the rocker covers the oil will overshoot the rocker ball and will cause them to burn. http://webcache.googleusercontent.co...&ct=clnk&gl=us

[Joe C.]

Re: valve adjustor nut, locking vs self lock

Just doing the valve adjustment on the race car before Monterey and I'm currious. The stamped rocker manufacterer included self locking friction nuts to adjust lash. In the past I've used adjusting nuts with a set screw. Think kool nuts by Crane. In a racing application do we have any opinions on one design vs the other. it sure is easier to adjust the lash with the self locking. jerry

If you use any brand of "Poly Locks", make sure that you turn the Allen setscrew and the 5/8" adjuster nut the final 1/4 turn AT THE SAME TIME for a positive lock. If you adjust your lash with the nut, and then turn/lock the Allen setscrew afterwords, this is often (but not always) enough force to cause the set screw to deform the top of the rocker stud for a positive lock. If course, your rocker studs are probably screw in type, with shoulders for guide plates, which all have flat tops for the set screws to dig into.

[Jerry G.]

Re: valve adjustor nut, locking vs self lock

With poly locks i usually get the lash then back the nut off a 1/8th turn then hold the nut and turn in the set screw until it touches the stud. Then I turn them both the last 1/8 turn. This puts a preload on the set screw. Seems to work until I forget to tighten one set screw. This just happened to me at the Portland race. ( bent pushrod and all) You can't make this mistake with the self locking but the concern is that they will walk out. So Clem's old racer trick is the Pal nut. Now I guess I can worry about the Pal Nut loosening and going into the pan. Makes you crazy sometimes.

[Jerry G.]

Re: valve adjustor nut, locking vs self lock

Clem, do you torque the Pal down so it doesn't loosen?? Jerry

[Joe L.]

Re: valve adjustor nut, locking vs self lock

Just doing the valve adjustment on the race car before Monterey and I'm currious. The stamped rocker manufacterer included self locking friction nuts to adjust lash. In the past I've used adjusting nuts with a set screw. Think kool nuts by Crane. In a racing application do we have any opinions on one design vs the other. it sure is easier to adjust the lash with the self locking. jerry

Jerry-----

GM recommends the self-locking type nut over all other types when using with stamped steel rockers arms. I do, too. This applies to both street and racing applications.

[Clem Z.]

Re: valve adjustor nut, locking vs self lock

Clem, do you torque the Pal down so it doesn't loosen?? Jerry

just snug them up and never lost one. don't you have magnets epoxied in the heads to catch the pieces of valve spring that chip off and cause the small scratches you see on the cylinder walls ??

[Clem Z.]

Re: valve adjustor nut, locking vs self lock

With poly locks i usually get the lash then back the nut off a 1/8th turn then hold the nut and turn in the set screw until it touches the stud. Then I turn them both the last 1/8 turn. This puts a preload on the set screw. Seems to work until I forget to tighten one set screw. This just happened to me at the Portland race. ( bent pushrod and all) You can't make this mistake with the self locking but the concern is that they will walk out. So Clem's old racer trick is the Pal nut. Now I guess I can worry about the Pal Nut loosening and going into the pan. Makes you crazy sometimes.

to do poly locks set the valve .003 loose,tighten the set screw while holding the adjustment nut and then turn the adjusting nut to the final lash setting. this will cause the lock screw to bite into the top of the stud