1978 chevy 350 flexplate issue

[1982K20]

Hi guys. Installed a new flexplate on my 1978 chevy 1/2ton 350 engine and noticed it was not running true. Is this a bad sign something is wrong with the crankshaft thrust/main bearings? Is there a way I can post the video I took on here?

 

[bucket]

I think it would suggest that the ring gear is not properly welded onto the flex plate. The torque converter bolts hold the plate itself true.

Is it out of round, or is there just a little run-out?

 

[fast 99]

The torque converter bolts hold the plate itself true.

Run out after being bolted up is a problem, before doesn't matter.

 

[bucket]

Run out after being bolted up is a problem, before doesn't matter.

Right. I'm wondering if OP is seeing runout in the ring gear, but not the plate itself.

Of course, I'm also assuming that it's bolted to the torque converter already and the engine has been running to notice that it doesn't spin true.

 

[fast 99]

Right. I'm wondering if OP is seeing runout in the ring gear, but not the plate itself.

possible, haven't seen that problem before but given the quality of parts today nothing surprises me.

 

[1982K20]

The engine is still on the engine stand so I’m just wondering will it get better once I install it in the truck and bolt up to the torque converter. The runout is quite noticeable on the engine stand

 

[bucket]

The engine is still on the engine stand so I’m just wondering will it get better once I install it in the truck and bolt up to the torque converter. The runout is quite noticeable on the engine stand

As long as it's properly seated on the crank and the bolts are properly torqued, it'll be fine.

 

[1982K20]

As long as it's properly seated on the crank and the bolts are properly torqued, it'll be fine.

Okay sounds good. Thank you