-
Another BBC out here at the lake broke another famous rocker stud so I thought I would post this. That makes 3 different guys out here that have broke one stud...and all of them were the arp's "best".
Something I found a while back.
Consider the ARP Part number 334-7202 "small block" rocker stud. The shank is much longer and the overall stud longer. This gets more of the roller rockers trunion riding on the shank...rather than the threads of the stud.
And since the stud is longer...you have more thread for the adjuster nut.
I'll be changing all mine to these over the winter.
-
If those are the "pro" series, it's possible the extra 20,000psi hardness (200,000 compared to 180,000 in the "high-perf" series) is getting into a brittleness issue with the instalation. The harder a fastener is, the more brittle it is, the more likely to develop cracks and break under strain than just bend.
-
Another BBC out here at the lake broke another famous rocker stud so I thought I would post this. That makes 3 different guys out here that have broke one stud...and all of them were the arp's "best".
Something I found a while back.
Consider the ARP Part number 334-7202 "small block" rocker stud. The shank is much longer and the overall stud longer. This gets more of the roller rockers trunion riding on the shank...rather than the threads of the stud.
And since the stud is longer...you have more thread for the adjuster nut.
I'll be changing all mine to these over the winter.Where did the stud break? What kind of valve train (spring pressure) and rpm?
Thanks for the heads up. Long valves for added installed ht. can be a problem. The small block studs are a good fix. If the rocker is riding on the threads, you're definately asking for trouble. Can't really blame the stud, if it's breaking at the threads.
-
Yea I have had to get into the ARP book and pick a stud that has the proper shank length. Even had to machine some of the threaded length off so the poly lock would function.
-
1. Were the studs 3/8" on top and 5/16" where they screw into the heads? Mine are like this but I run a flat tappet blower cam, relatively soft valve springs and I don't turn over 6,000 RPM's.
2. Were the springs stiff like you would run with a roller cam? Roller cams require strong springs because the cam profile is made for faster valve openng.
The American way - "If stiff is good - stiffer is better" will kill even 3/8" studs. If thie springs are real stiff, you have roller rockers and you run high RPM's then a stud girdle is definetly in order.
Just my .02 worth
L J
-
I cannot find a reason to not run stud girdles. Even if you are running a pump gas 4600rpm warrior. Just a quick hop out of the water and the thing can wind up. A cheap set is better than nothing.
-
For the record and to clarify:
All were large roller cam 7000 rpm plus engines. 220 lbs of seat pressure or more. Not sure of the length valves in all these particular instances. And they all had girdles. It doesn't mean for everyone to yank the rocker studs out and go this direction. Its just something that those building high horespower applications might want to look at.
The longer shank offers better support of the rocker trunion and the longer thread gets more thread into the adjuster nut. Every stud I ever saw broken is always at the thread area because the roller rocker trunion should ride on the shank of the stud (as much as possible)....not the thread. Yes..long valves aggravate the problem.
And just because you run a stud girdle is no guarantee the pushrod will not come out of the rocker when a stud breaks. Odds are it will.
-
Even had to machine some of the threaded length off so the poly lock would function.
I had to do all kinds of funny stuff to the studs when I got my old set of Dart 320's----it was a mix and match sorta thing----had to put head bolt washers under some to get the trunion off the threads and enough thread for the stud girdle nuts!!!
-
For the record and to clarify:
All were large roller cam 7000 rpm plus engines. 220 lbs of seat pressure or more. Not sure of the length valves in all these particular instances. And they all had girdles. It doesn't mean for everyone to yank the rocker studs out and go this direction. Its just something that those building high horespower applications might want to look at.
The longer shank offers better support of the rocker trunion and the longer thread gets more thread into the adjuster nut. Every stud I ever saw broken is always at the thread area because the roller rocker trunion should ride on the shank of the stud (as much as possible)....not the thread. Yes..long valves aggravate the problem.
And just because you run a stud girdle is no guarantee the pushrod will not come out of the rocker when a stud breaks. Odds are it will.
broke one in march, last pass of the weekend. after 5 years and over 450 passes, that's the sum total of damage, so not too bad. replaced 'em all.. with over .700 lift with a solid roller deal, those studs can weaken even with the girdle. but, the crane golds just keep on keepin on..same since 1998 (knockknock on wood).
