[GoFast Beaumont]

Anybody seen something like this before. Is this from me just torquing the poly lock too much? Fatigue? General use/old age?

 

[bracketchev1221]

 

[427L88]

I;ve split them before by overtorquing. so yeah.
Sometimes off fractures caused by bad harmonics - aka float. BTDT.

Nice looking rocker arms!

 

[shovelrick]

Doesn't look like you had a lot of threads down on either of those poly locks but I'm far from a pro, edit yes those are nice looking rocker arms what brand?

 

[BillK]

Can also be because the stud isnt long enough and you dont have enough thread engagement. Looks like your allen screws are down in there pretty far. If that is a 7/16 stud then you really should have at least 9-10 turns of thread engagement. More would be better.

Cant say i have ever broken one tightening it down and I get pretty aggressive with them.

 

[shovelrick]

I'd be willing to bet harmonics from not enough threads too, NO engine pro but a mechanical contractors thinking

 

[bracketchev1221]

Can also be because the stud isnt long enough and you dont have enough thread engagement. Looks like your allen screws are down in there pretty far. If that is a 7/16 stud then you really should have at least 9-10 turns of thread engagement. More would be better.

Cant say i have ever broken one tightening it down and I get pretty aggressive with them.

I believe it’s from too short of a stud also. I like to keep a poly lock set screw flush or just above the nut. Mine was on an engine I bought with the car so it needs help!!!

 

[GoFast Beaumont]

thanks guys, yea i am suspecting over torque and fatigue but just wanted to check. Hopefully they still make the poly-lock for these. They are a .600 body but taper smaller right where it meets the rocker arm trunnion.

in regards to threads there is just over 0.5" of contact, the picture is a little deceiving. should be more than enough for a small ZZ502 camshaft movement.

The rocker arms are a original set of Comp Cam Pro Magnums (chromoly construction). They definitely have served me well being on 7 different motor combinations and thousands of street miles.

 

[GoFast Beaumont]

 

[Malibu ss 64]

This set from jegs should work.

JEGS 20972: Poly Locks [7/16 in.-20 Thread, Set Of 16] - JEGS High Performance

Buy JEGS 20972 at JEGS: JEGS Poly Locks [7/16 in.-20 Thread, Set Of 16]. Guaranteed lowest price!

www.jegs.com

 

[shovelrick]

I have a set of ARP 235-7205 studs that didn't work for my build I'd let go cheap, pm me for details if someone needs them