70 440 internal or external balanced?

[Mopar2You]

I had a 76 block in my 70 roadrunner, it has an external harmonic balancer I believe (was on the pulleys attached to the crank). I put it on my 70 440, and now it has a VERY large vibration at over 3k rpms.

Is the 70 440 externally or internally balanced, and the same for the 76? If they are both external, then are they the same weights? Etc. etc. etc..

Thanx!!!!!!

oh, the site for my car is updated if you want to see the work I have done to it.
http://www.cardomain.com/id/lordofchaos187

[Tarrbabe]

76's had a cast iron crank and were externally balanced. The 70's had steel cranks and internally balanced. You need to use a pre-cast crank harmonic balancer. nuff said unless you have the engine rebalanced to use the newer balancer.

[AndyF]

A '70 HP motor would have been externally balanced.

[Tarrbabe]

In 70, the only 440 that was externally balanced was the 440-6pak. They had to be externally balanced to make-up for the oversized 6-pak rods. The rest were internally balanced in 70. Mother changed to cast cranks in 74.

[dirty dan]

HI If you have a 70 440 you need to use a thin balacer. Any balancer from a 383 or a 440 as long as it is from pre 73 it will solve your problem. DON`T run the engine untill you get the right balancer!!!! Or it will knock the bearrings out of it. Contrary to what you may have read it was 73 when mother mopar began to use a cast crank. The 73 is not hard to pick out in a croud . It has a very thick balancer even thicker then on your 76. If you have not yet removed the counter weight from your converter you need to. This WILL take the bad vibes out of your 440!! . Happy motering

[Tarrbabe]

Dirty Dan, you may be right about the 73 440's having cast cranks but thats not what is in my Mopar Engine Book. If he is using the torque converter with the weights on it, I know your right if he has the steel 70 crank. That can cause really quick damage. I know that Mother used cast cranks in the 71 model 2 bbl 383 as I had one in my 71 Charger.

[John Kunkel]

ALL'70 HP 440's have the big rods, six pack or not and are externally balanced.
The big rods can be found as late as '74 on some forged crank HP motors. (Cop cars mostly)
'73 was the first year for cast cranks in the 440. After mid October '72, standard performance 440's could have either cast or forged cranks. All '73 HP and pre October 440's will have forged cranks.

[451Mopar]

I'm with John on this. I have a 1970 440 Hp block, stock 4-bbl, and it has the counterweighted front dampner like the six pack engines.

[Tarrbabe]

I guess mother lied.