413 harmonic balancer

Are these engines external or internal balanced. I broke my harmonic balancer.

Internal

Yep, Rapid is right. You can use a regular neutral-balance 383/440-style balancer no problem.

All the 413 motors where internally balanced, there are two different balancers for them just like the 383 and 361 motors and the 1966 440 motors, the pre 1967 motors have a straight tab on the timing cover with the zero mark on the top and the zero TDC line on the balancer is higher up on it at TDC than the 1967 and later balancer that where used with the curved tab timing cover that has the zero mark on the tab in the center of them
OP, my message is make sure which one you have and need to replace it with, you can verify TDC and then add a timing tape onto the new /replacement balancer you use to get the zero mark where it should be for tuning Lots of different ways to skin the kitty

http://www.440source.com/dampers.htm