Flat tappet lifter failure

[Alan Roehrich]

Originally Posted by goinbroke2

My cam is .398 and 250@.050 Never had an issue breaking in dozens of other cams but.. should I put light break in springs on then switch once its broke in??

I've been using GM EOS for 40 years and have never had a cam lose a lobe, but again, I've never run the spring pressures and lobe profiles like this either.

It is ALWAYS a safer bet to run lighter springs, and or low ratio break in rockers. I bought a set of 1.3:1 rocker arms just to break in the cam on one engine, rather than disturb a set of high priced heads that didn't belong to me. I know several builders who keep a set of Shubeck lifters set aside, and used them to burnish every new camshaft, then swapped to break in springs or rockers, and put in the new lifters that were to stay in the engine.


I use moly disulfide paste on the lifters and camshaft, then I use a mixture of Brad Penn oil and one of the extreme pressure red assembly lubes for assembly. Then I use Brad Penn or Lucas break in oil for the break in on the dyno. My engines are all pre lubed, the carburetor is primed, and the ignition spark timed, so that they do not crank for an extended period of time. They start, go to 2500 RPM, get the timing set, and get run between 2500 and 3500 for a full half hour, without stopping unless there's some sort of emergency, like a massive leak, or excessive oil or water temperature. Then they get the oil drained, the filter swapped (I prefill my filters) and any change to the valvetrain, springs, rockers, or both. Then they get 15-30 minutes more run in with fresh break in oil. We check lash, etc, and then start pulls.