Mr. Sinister
Devastation Manager
Sorry for inserting info guys….. I am glad nobody ever breaks a single part. I wonder do you even use oil?
Broken rocker arms two weekends in a row
- Thread starter Les Gibson
- Start date
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Mr. Sinister
Devastation Manager
You know I read one of your recent posts about how you pulled off the maintenance on your car and motor home all in time to beat the rain, and I thought that was impressive on two parts the fact that it was important enough to do it and get it done no matter what.
Now I have to call it a story.
Good Luck.
Not sure what you are talking about but yes I do maintenance. As a matter of fact my car trailer is sitting with a tire and drum off waiting for trailer brakes to hopefully arrive from Texas tomorrow so I can leave Tuesday for Norwalk. They passed inspection but with two more races this year I wanted them done. Do I like working on cars??? No. Do I do things that I have proven don’t need done in 47 years of racing??? No. Like I said my last broken inner spring was in the 1980’s with a .750 lift roller cam. I probably broke three of them then the problem went away. I think my machinist may have overlooked something setting up my 906 heads. Knock on wood I’ve never hurt a keeper or retainer. I mostly run titanium but if I remember right titanium fatigues quicker than chrome moly steel. And everything gets 10 degree stuff.
It's a feel good thing, just like backing off the rockers.
My race engines never get spun under 50 degrees temp. It sleeps until then
pink340swinger
Well-Known Member
Did the OP find the root cause of his problem? I'm betting on weak/ permanently compressed springs causing bounce and hammering on the rocker as the cause. Here is a pic of
1 new, 1 compressed spring. Both from the same batch/ manufacturer built date. The weak/compressed spring caused valve float/bounce leading to hammering on the rocker arm which lead to it's breaking. Excessive/extreme valve lash can have the same results. Backing off rocker arms between long periods of non-use helps longevity. Same for rod bolts in aluminum rods, most quality aluminum rod manufacturers highly recommend it during long periods of non-use.
Wholly crap you guys are right. I pulled a spring to check them and would you look at that.
If we had big frozen lakes over on the west Coast and ice drag racing I'd love to do that.
pink340swinger
Well-Known Member
I run PAC 1355 springs on the intake valves. New intake springs are installed @2.100" and have 450# spring pressure at that installed height. 780# spring rate and 1.130" coil bind. 1200# @ 1.175". They lose roughly 50# after break in. The collapsed spring has 295# at that installed height. The exhaust springs have a slightly different rate as the exhaust valves are lighter and don't have as much lift. You're welcome to come over with your own spring tester and compare it to the 2 that I use.
No I trust you. I just don’t see an issue and never have. I only shift at 6700-6800 so maybe that helps. My spring are still on my 360-1 heads that I ran for five years so I can check the pressures when I take them apart. 5 years on a .650 solid lifter cam
Just to let everyone know, I replaced the two exhaust rocker arms that broke. Went Winterport Dragway and made 7 runs between time runs and eliminations and the car ran fine. I looked everything over at the end of the day and all looked well. I'm calling it problem solved. I'm still planning on replacing all the rocker arms over the winter. No apparent cause for the breakage other than perhaps the age of the rocker arms themselves.
Mr. Sinister
Devastation Manager
Have fun!
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