help a friend out 63 barracuda had a shop put motor in they had no idea what they were doing. after 2 years he pulled car out Im helping him get it running it has a 340 never started with edelbrock heads rpm intake and holley
went to put torque conv bolts in and found out motor would barely turn over with a breaker bar. found the balancer was hitting timing cover pointer for timing mark and bottom of water pump. its def a 340 motor is there diff balancers for small blocks?
i looked on mancini and summit and jegs and looks like 7 in or 7 1 /4 is there also a 6.5 in balancer?

 

Sounds like your trying to use a early timing cover with a later damper.... So yes you need a newer cover...

 

I found a 7 in balancer aftermarket neutral balance can I just swap that? I know its a 340 I think forged cranks were neutral balance and cast cranks had external balancing? the balancer I took off was neutral the torque converter has two small weights on it certainly not like the later 360 weight looks like the size of a 1/2 oz tape weight for wheel balancing 2 of them right next to each other like its weighted I didnt build this motor Im fixing someone elses screw ups.

 

Sounds like your not dealing with a easy fix....
You can do a lot if you know the crank is a 340 and internally balanced... You will be good running neutral what ever !!!!!
But if it had a 360 crank... These are Externally balanced... and you could have 1 or 3 cranks ans 1 of 3 dampers... And you can have 3 choices of Converter weight arrangements..
I ran into one of those (someone else built it) deals... Got the rote crank>>> Dampner>>> Welded the weights on the convertor>>> still had a vibration>>> Had to take the whole asm and have it all rebalanced!!!!
I was so pissed at the guy that sold me that POS i could have killed him.... To this day, that engine is still out there at some track winning races....

 

I bought a 360 la ram truck 86 had a horrible vibration in it at 75 mph couldnt figure it out they told me it had a new trans in it turned out the torque converter was for a 360 magnum not an LA . swapped converters vibration gone took me a while to figure it out.

 

Yep and then there are the Magnums....