Does anybody have experience with Chevy straight 6's? I have a vibration.?

Question

I know it's the engine, because we've separated the torque converter from the flex-plate and the engine still vibrates when the RPM is brought up.

Driving down the road the vibration begins at about 40 mph and gets worse from there.

I've replaced the harmonic balancer, that's not it. I've also replaced the mounts.

Has anybody had a cam gear dis-bond? Does that ever happen?

This is a well-maintained 250ci with almost 300,000 miles on it, but it doesn't burn a drop of oil and doesn't have any knocking or ticking noises at all.

I know this is a 'way-out-there' question, so few people dink around with those old 'thrifty-six's'. But this is our daily driver and if anybody out there knows what's up with this old boat anchor please let me know.

Thanks!

Answer 1

check for a bent pulley or fan blade

but you flex-plate might have lost a balance weight  and is the culprit

its unlikely that a can bearing or cam will be the cause without a knock good luck