^ many times on that '85 they started the 50 oz and pre was 28 oz

 

My block is an 1980. I guess i should put a photo up huh

 

82 is when they changed balance. In 80 and 81 ford used a 255ci destroked 302 in the mustang.

 

Get the casting number, it should be on the bottom near where the starter would mount.

 

'82+ (when the 302 was "reintroduced") are 50 oz. balance factor.... 80-81 4.2L were also 50 oz., leaving the '79 as the only 5.0 Mustang with a 28 oz. 302.

 

It's also gonna depend on whether or not you get your assembly balanced. You take it to someone with a balancing machine to balance all the internals, and you can do it as 28oz factor, or 50oz, or 0 if you have the stuff for it. As long as you have the right balance factor balancer/flywheel, they'll balance the assembly to whichever.

 

not to deviate from the topic....
but if u were to add aluminum underdrive pulleys, since they are alot lighter than the steel stock pulley, would it throw off the balance of the motor? Im pretty sure the crank pulley i have is at least 1 pound lighter than the stock steel one. I have no idea, does anyone know?

 

no, the pulleys should be balanced perfectly, and have no bearing on the balance of your engine

 

cool thanks

 

is there a diff between the two if u had an unbalanced crank with the option