Mythbuster: continuing project thread of my 1303 '75

[dub_crazee]

Bizarre!!! Glad there was no damage! Put any decent runs in before the damage?

[Wally]

Originally Posted by dub_crazee

Bizarre!!! Glad there was no damage! Put any decent runs in before the damage?

Not really, it happened on the 2nd run. First run was a track-sensing 12.8/181km/h, but I had hoped for an 11-run this day...

[michael86]

Could it be a age related that the rockers broke.
The material getting brittle over the years.
I've never seen this before.

Glad it was only two rockers and no more damage.

Tiki

[Humble]

That's really strange that it snapped off 2 rockers in the same fashion on the same cylinder. It's amazing there's nothing else wrong, you really lucked out

[Wally]

Originally Posted by Humble

That's really strange that it snapped off 2 rockers in the same fashion on the same cylinder. It's amazing there's nothing else wrong, you really lucked out

Yeah, I did huh?

Might indeed be something like metal fatique Michael, but you would have thought this would have happened to others then too? Never seen it before and especially not at two on the same cylinder...
I am still very much puzzeled by the whole thing.

[effvee]

Better go back to basics. Seems like a lot of pressure on the nose of the rockers. What kind of spring pressure are you running? No spring coil binding? I would have thought your push rods would have bent before the rocker did that? Maybe have a very close look at the other springs for spring binding. This is pure luck that you did not damage this engine, very good luck