last week, I was brake torquing, and then I heard a loud "POP". ended up being 2 broken pushrods on the same cylinder. I replaced those, and now a pushrod on a different cylinder keeps bending it bent the first time when I was driving home (very easily) just after replacing the first 2 bent pushrods. Then I replaced it and while I was setting the lash, it went "POP", splashed some oil and was bent. Samething second time. Samething third time. It would clack, then as soon as it stopped clacking, it would go "POP". Anyone got any ideas of what's causing this?

engine/heads have about 300 miles on it
heads are rebuilt stock, springs are matched to cam, stock rockers, stock pushrods, SLP 51006 cam (right around "500 lift), stock hydraulic roller lifters. Lifters/pushrods/rockers have 73,000miles

'87 350 SBC

 

Have you checked the alignment of the rocker? The stud may be bent or if screwed in may have been tapped out of line with the rest.

 

I'd SWAG it as your stock rockers are binding on the stud. The slots aren't long enough, BTDT. No matter what you have bind in the valvetrain someplace. May not be the springs but it could be a retainer to guide bind.

RBob.

 

Sounds like too much cam for the rest of the valve train.... or rather, not enough valve train for the cam.

If the valve springs are stock diameter (1.25") then they are at their absolute max lift, with .500". That's a possible danger point.

The immediate casue of push rod failure is probably the end of the slot in the rockers binding on the stud.... too much lift for the weenie stock rubber rockers. Look at the rockers and the studs where you've had broken push rods, on the rocker at the end of the stud slot closer to the push rod seat, and on the stud right below the where the rocker ball sits on the side facing the push rod hole in the head; you'll probably see a shiny spot where they've been interfering.

 

what rockers would you guys suggest? I have the centerbolt heads, and need self-aligning rockers.

I've heard that aluminum rockers won't last as long, but do they last long enough? stay with 1.5 ratio or goto 1.6? the springs should be good to .550" lift.

 

That's what they all say; but are they paying for the damage??? They've got your money, and now you have to deal with the issues.

Stay with 1.5s. You've got problems already, why tempt fate.

I would not recommend aluminum rockers. Look at the Comp steel ones; Comp 1417 if you don't want full rollers, 1317 if you are willing to deal with stuff that's too big to fit under you stock valve covers. That may sound trivial, but it's a bigger problem than most people realize until after they put some cheap replacement valve covers on their motor, and then wonder why they have all these weird problems that they didn't anticipate. I'd recommend the 1417s.