SBC 350 vibration

[Cobra_Crazy]

Hey Y'all,

I have been perplexed by a vibration that starts around 1200 rpm in my sbc 350. I originally thought it was in the transmission but after a rebuild and a new torque converter, it was still there. The damper appears to be fine and hasn't slipped as far as I can see. The engine runs fine, responds well but has an annnoying on/off vibration in the motor. I've got side exhaust and it broke the right side mounting bracket. a while back. Any ideas or recommendations. Someone told me to check the flexplate, it looks fine to my eye but maybe there's something else I should be looking for. Thx
Tom

[Oldcar_Mechanic]

Have you checked the fan?

Sometimes they throw a blade or part of a blade on two piece blades and that will do it.

Ron

[Cobra_Crazy]

thx Ron,
I've thought about that but I use electric fans mounted to the radiatior. They don't normally come on until the temp gets up there. Someone told me that it could be a journal bearing but I'm hesistant to just start tearing things apart. Any other ideas?

[Oldcar_Mechanic]

How about the motor mounts?

[Cobra_Crazy]

Ron thanks. I've found the problem. Who would have thought it was the thrust bearing. It wore down and I was told that it should only have .003 slop but it had a 1/4 inch. Once I get it back together, we'll see what happens. Thanks again for the tips.
T:)