360 Internal or External Balance??

There were cast crank 340 engines in model year 1972. But it seemed like a lot of leftover parts from 1971 continued into 1972 until they were used up.

Here are some helpful links on what to look for.

http://www.moparts.org/Tech/Archive/smallblock/5.html

http://www.moparts.org/Tech/Archive/motor/8.html

http://www.moparts.org/Tech/Archive/conv/8.html

There obviously were a lot more forged crank 340's built because they were manufactured from 1968 into 1972. Cast crank 340's were only manufactured from 1972 through 1973, which was the last year for the 340.


To add a little to what tobysoldblue said - while 273 cranks can be installed in a 318 and/or 340, it would be wise to rebalance the rotating assembly. Different cranks have different weights. A casting is also lighter than a forged piece. This actually makes the counterweights lighter and requires external weights in most Mopar applications. 318's are an exception. Piston and rod weights can be different in different years also.


Also, I forgot the transition year, but very early 273 cranks had a smaller converter register and will not accept the newer/modern torque converters which had a bigger "snout".