Thread: 429 Cobra Jet. Internal or external balance??

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Here's a blurb from one of the aftermarket damper manufacturers

Big Block 429-460 Ford - This damper utilizes a separate counterweight that is a spacer that goes over the crank and behind the damper. These weights are available from your Ford dealer (#M-6359-D460) and must be used unless the engine assembly has been converted to an internally balanced engine by incorporating heavy metal in the crankshaft.

I can't remember that my 429 had this spacer/counterweight, so maybe the weight was part of the damper like it is on a 400 smalll block Chevy. It has been too long and I'm too old.

Feel around behind the damper and see if you can feel an eccentric offset weight as part of the damper assembly or a separate offset spacer weight as described above. If you determine that the thickness of the damper is the same all the way around and can feel no offset weight, then the motor is internally balanced. Another area to check is the flexplate. I know Chevy also used a weight welded to the plate, but I'm not sure if Ford did or not.