lifter trouble

572 chevy,8-71 hi helix,60 over, 12to1 static compression, tractor pull engine,heres the problem.Ip put 25 passes a season and i break a roller lifter sometime every year.springs have been checked and renewed regularly with 280 lbs seat pressure. I have used crane crower and comp cams lifters and broke them all.any suggestions? thanks Glenn

 

Are you bending any pushrods ?. Int. or exh. lifter breaking ?. What type of ignition and how much timing .

 

broken lifters

It is very possible to bounce the lifter on the lobe if the "harmonic" is right, that all depends on the grind of the cam, the rpm, the weight of the lifter, the length of the pushrod, and the spring pressure. I had the problem one time and it only happened on the intake side at between 7000-7800 rpm sometimes during the burnout or going downtrack it did not matter. Crower told me I was having a harmonic problem and I thought he was off his "rocker" I changed my pushrods from short 5/16 to longer 3/8 and took the tall lifter out put the shorter lifters in, and removed the rev kit, problem has been gone ever since. I know it is hard to believe but have since seen the same problem on a friends car, (different combo) cured it by changeing size and weight of components. Call crower and see what he says. Good luck.

 

What about detonation? I know on a fuel car when it detonates, it will usually break the lifter also.

 

More Lifter Information

I have always broke an intake lifter. From what I can tell, the roller breaks in half. Rollers do have the internal oil passage. I run an upgraded super mag 3 and use 36 degrees total timining. (I know this is a little fast, but the motor seems to run it's best here). A push rod is sometimes bent when the lifter fails. I have never bent a push rod otherwise. Detination is a possibility, because I usually break one blower belt a year.

 

I would think spring pressure is a little lite. By the time you figure the square area of the intake valve times the boost pressure which would subtract from the seat pressure your down pretty low. What size push rods?
www.topeliminatorwest.net

 

You might want to try turning your timimg down , sounds like a detonation problem . I had a similar problem , exploding lifter wheels , bending manton 7/16 pushrods , breaking jesel rockers , ripping the stand bolts out of the heads and so on . I turned the timing down and all probs went away .The spring psi. does seem a little low but if that is what your cam mfg. recommends it should be okay . Any marks on top of the pistons from the valves hitting ?. Just my experience .

 

spring pressure

your springs are too soft look for 800/900 lbs open problem solved.