broken 1-1/2 M rocker arm

[mike st]

A little success and little disappointment in the shed this weekend. I got the 1-1/2 M going but the rocker arm broke after a few minutes of running. Not sure why. I adjusted the gap according to the owner’s manual – push rod just touching the rocker arm with the ‘exhaust’ mark on the flywheel lined up with frame mark. It sounded great for the time it ran, real strong with a sharp bark through the muffler. It’s actually a big disappointment as most of this engine is original equipment – only the piston rings have been replaced. I plan to have the broken one brazed up to get the engine running reliably rather than risk another part. I’d prefer to put an original back on, so if any one has one laying around and they’re will to part with it, please let me know. Still not sure why it broke though …we’ll see how the brazed one stands up.

If you have any ideas why this might have happened please let me know.

Thanks!

Mike

[Kevin O. Pulver]

Mike,
No telling what that engine has been through before you got it.
Doubtless the rocker was stressed already. Maybe the exhaust was half stuck once and someone rolled it over.
Or maybe it was just plain a bad casting and had finally had enough.
It shouldn't be too hard to find another one. Or a good braze job doesn't look bad either. Kevin

[Tom Marshall Jr.]

When you get it repaired, turn it over slowly and watch the spring to see if the coils touch together. (coil bind). also look at the spring cap to see if the center part hits the valve guide. When the cam lobe it open all the way you should be able to push the valve open a littel more. if so your rocker just broke on its own.

[Al Wait]

That is a common enough engine that I am sure a reproduction rocker is available from someone like Starbolt. No one need ever know. Al Wait