250 Crankshafts

[Anonymous]

Can anyone tell me if all U.S. 250 cranks are the same? It seems to me I've seen some that looked fully counterweighted, and some that didn't. But then I thought I'd heard all small Ford sixes are internally balanced:

 

[xctasy]

All the US and Aussie 250 cranks have only 10 balance weights, as far as I know. This is because the oil pump drive gets in the way with a fully counterweighted crank. Some Aussie guys use the later OHC 243 cube 12 weight cranks in there 250 X-flows. They don't fit the US block unless the trust bearing is enlarged to suit. The front nose has a larger diameter too. Aussies used the smaller 200 gears on there 250's to save tooling costs and weight, while the US 250 is really heavy duty.

Aussie cranks on the 250 based, but similar 240 and 243 OHC six had 3 versions of special 10 or 12 counterweight versions. The latest 243 DOHC has a different front cover as the pump is a Jap-style trochiodal number. It wont bolt in unless you spigot the existing crank snout on to the later BA Falcon crank, and then you have to sort out the rope seal, thrust bearing, and oil pump clearnance issues.Oh, the bearing mains are 2.65", rather than 2.4" too
In short, stick with what you have!

The US 240 or 300 is fully counterweighted, I think, but the bores are 400 thou furter apart, and you have no hope fitting one.

 

[Anonymous]

Thanks. It sounds like any 250 US crank will work then.

I had two 250s, one with a bad crank and a good top end, the other with a good crank and a scored cylinder. I tossed the bad crank without comparing the two (stupid!), then later it struck me that it looked different than the one I was putting in. Seemed like the one I was installing had lighter, perhaps partial, counterweights.

I guess the only sure thing is to have the whole works balanced.