Thread: 428 or 390

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Originally Posted by Mike P

If the engine is a 428 (and complete) there will be a a counterweight on the sleve behind the harmonic balancer. The 390 is internally balanced and will have sleve without the weight.

The 12th picture down on this site shows a picture of the sleve with the counterweight.

http://www.mustangandfords.com/techarticles/15999/

Mike only the 428 SCJ used the balance sleeve or "cookie cutter" as some guys call it behind the harmonic balancer. The 428 and 428CJ's don't have that..stock from the factory anyway. The SCJ used heavier LeMans rods and Ford took the balance pad off the #7 crank counterweight on the IUA SCJ crank and put more weight on the nose with the balance sleeve. Not the best idea but it worked and was a low cost solution vs making another crank casting for the SCJ. If you put a std IU 428 or IUB CJ crank next to a IUA SCJ crank you'll see exactly what I mean. The link you posted also mentions this about the SCJ crank and balancer.

G.