340 Vibration

[GrizandLinna]

Looking for a little wisdom. I bought a 1970 Dodge Dart Swinger and the gentleman said he had the engine rebuilt. Don't know how long ago, but it seems pretty stock. I finally got it to run and at idle it is smooth as silk. However, as soon as I give it gas there is a vibration. I thought at first, it was in the drive line, but I can sit in the garage and slowly rev it and the vibration is there. It doesn't have a miss, but when you drive it down the highway, you can feel it in the car. Could it be as simple as a vibration damper, or do you think I should take it apart and see if there is some imbalance inside? Any info you can offer would be appreciated.

 

[RAT ROD AL]

First thing I would check is the casting date on the side of the block, and see if it has the correct V Damper on it.

 

[jazak5]

First thing I would check is the casting date on the side of the block, and see if it has the correct V Damper on it.

wouldn't you have to pull the oil pan and look at the crankshaft??

 

[Bodyperson]

You can sneak a peak with the timing cover off

 

[Kendog 170]

Can't hurt to check the flex plate and bolts but probably isn't the issue.

 

[jazak5]

Can't hurt to check the flex plate and bolts but probably isn't the issue.

along that line look through the trans inspection cover and see if the torque converter has weights on it

 

[George Jets]

1970 340 would be internal balanced, neutral balanced engine.

No lopsided weight on the front balancer, like is apparent on the 360 externally balanced engines.

Mid 1972 340s went to external balance front weighted balancer. A special balancer for those 340s.

360 external balancer below.

Neutral balance, balancer below.

☆☆☆☆☆

 

[GrizandLinna]

I found the vin stamp and it's a matching motor, but the trans doesn't seem to be stamped. I will check the balancer and torque converter.

 

[cudamark]

Also, check for solid engine/transmission mounts, and exhaust mounting/routing.