Balance question.

[Dragonbat13]

I just tore down a 318 with a cast crank and found a spun rod bearing. Crank wiped out. I got a forged crank that can replace it with , but I am not exactly sure what it came out of. I know its not a 318-3 truck crank.

With the stock rods and pistons, will I have to re-balance the assembly to swap over to the forged crank?

 

[Robbie2734]

What year 318 had the spun bearing, and what is the casting number on the forged crank? I believe the rod/piston weights are very close up to the Magnum series. That is for car engines only, truck could use heavier rods. If it was me, I'd have the rotating assembly balanced. Your forged crank should be from a 67 to 70 year 318, or it could be a 340 crank too.

 

[krazykuda]

I just tore down a 318 with a cast crank and found a spun rod bearing. Crank wiped out. I got a forged crank that can replace it with , but I am not exactly sure what it came out of. I know its not a 318-3 truck crank.

With the stock rods and pistons, will I have to re-balance the assembly to swap over to the forged crank?

You shouldn't if it was made in a small block originally with the stock "light duty" 318 rods.