I am working on replacing a 351m in a 79 F-250 to a 460 the 460 is a 1978 motor. I am planning on keeping the manual transmission. I need advice on what I need for a flywheel. I'm fairly sure that the bell housing will bolt right up. Im just unsure where to get the right flywheel ( balanced-unbalanced) (and off what motors or years could I rob a flywheel?) Any help greatly appreciated.

 

BUMP!

Anyone?

Isn't the externally-internally balanced thing in 1978/1979 for the 460?

 

1979 is the cutoff so you need a neutral balance flywheel for a 1978 engine. a 390 flywheel should work fine if you use a 390 starter, or you can spend more and get the proper 460 flywheel. youll need a diaphram clutch set because the 3 finger clutch set wont fit without a spacer between the bellhousing and block. the 351m bellhousing is shallower than a 460 bellhousing... youll also need swap motor mounts... cheap ones can be had for about 90 dollars from summitracing.com

 

if it is a manual transmission the with a removable bellhousing the 351M and 460 bell housings are the same as far as flywheel goes they used the 460 motor up to 95 i think but if you have the 400M (a 351M block with a windsor crankshaft i think that the flywheel you have will bolt up and work on the 460

 

the 460 motors are externally ballanced i believe

 

There was both, after 79 was externall balanced, earlier are internally balanced.
I never can figure out which one 79 is though

I pulled a bellhousing off a 2wd camper special with a 460 and the NP435 and it was exactly the same depth as my 400 bellhousing that I already had. I've been told the spacer thing more than once though, I just havent seen a bellhousing that was the wrong depth yet.

The easiest solution is to get a flywheel off a newer externally balanced 460 and have it neutral balanced at a machine shop. You could buy it new from L&L for too much money, or you could use a 390 flywheel which are plentiful, but sometimes people end up with starter nightmares on the 390 flywheel.

Good luck and keep us posted on how it turns out.