broken rocker adjuster

[cory cotherman]

breaking in my sc spec engine and 4min in I heard a ping. shut it down and found this. Does anyone know what could cause this? and where do I get a replacement? thanx cory

[Vic Skirmants]

Check the end of the pushrod; I'm guessing it wasn't seated properly in the adjuster cup.
I assume Stoddard has those.

[Geoff Fleming]

The exact thing happened to me about a dozen years ago. I imagine it is just a random event, having put over 100,000 miles on 356s and never experiencing it before or since. I discovered it during a valve adjustment.
Get me your address and I'll drop a replacement in the mail.

[C J Murray]

I would think that you did not have the pushrod seated in the lifter when you assembled the engine. When it ran it seated causing way too much play and the pushrod caught the edge of the adjuster cup the valve then hit the piston and then the adjuster cup broke.

OR, the valve stuck in the guide, allowed the pushrod to shift to the side, then the piston hit the valve, then the adjuster cup broke when the piston pushed the valve closed.

OR, the rocker stuck on the shaft with the valve open then the same as above. I just had this happen in a race engine. A little weird though.

Check for a bent valve or a sticky valve or a sticky rocker.

[Dick Weiss]

When rebuilding an engine (or replacing a pushrod), I squirt some oil into it and can feel the end fitting the tappet's
ball-socket which makes sure the end is in place.
If the end isn't in place, you really can't adjust the screw properly and be able to rotate the pushrod.

Dick

[C J Murray]

It takes a lot of force to break the cup. Ultimately it breaks because the piston pushes on the valve and because the pushrod is not seated in the cup but is on the edge but this holds the valve open too far where the piston pushes on the valve breaking the cup. The only way the pushrod becomes unseated is if the valve or rocker sticks or if it was not fully seated during assembly.

[cory cotherman]

thanks to geoff for the replacement adjuster! got it all back together. bore scoped the cylinder to make sure there was no damage... all is good. adjusted the valves. started her up and runs great. just finished my 20 min cam break in today. ready to reinstall and start my ring break in. thanks all.