Senior Tech Team
Join Date: Apr 2012
Location: Yerington, Nevada
Re: Problems with Mr Gasket screw-in studs
"I tried "cleaning" the threads on that stud by driving a nut up and down but it destroyed the threads:
Two things about threads and studs,
First, the threading of things in an engine
Conventional threads are usually ones that have their ends shaped into a sideways V. These studs run regular type nuts and are not usually used for engines.
The threads used on most engine applications are called "roll", or, "rolled" threads. These threads do not come to the V shape at the bottom, nor top of each thread end, they come to a curvature at each end of the threads. Look at a threaded fastener, the V will literally look line a V at the thread ends, the rolled, a modified S.
To "chase" a rolled thread stud, or bolt, with a V type thread nut, die, etc., is to ruin it. The V at the end of the regular thread literally cuts away the curved end of the thread on the fastener, AND on any rolled thread hole in the block, heads, like main bolts, head bolts, studs, al of them. So, don't run a regular thread anything on a rolled thread hole, stud, bolt, fastener.
The reason rolled threads are used for engine fasteners is they are considerably stronger than regular V threads, and don't usually cause thread issues.
The next thing on a rocker arm stud is the end that the lock sits against. If we look at a regular V thread stud, its end will show some sort of curvature, or other situation. A rocker stud must have a FLAT cut end to match the poly-lok set screw. If the regular, non-flat stud is used, the lock screw will no seat against the stud correctly, can cock the poly-loc off center, and/or come loose.
For more ingo on regular v, and rolled thread fasteners, look on the ARP site, and google 'V treads' vs 'rolled threads', lots to learn.