Thread: 391/361 steel crankshaft info

Tweet

My experience with the 391 crank is that it is very stout and will take about any abuse. Just remember, you'll have to have the front snout turned down to the FE size if your going to use FE timing chains, front cover, and balancer.

I've had a few 391's break cranks, but it always happens after the bearings go away, so she's screwed anyway! 318 trucks do the same thing, where a cast crank will rattle on for weeks with loose bearings a steel one will break. Had it happen on diesels, too.
By the way, if you are going to use a truck block, bear in mind that the pilot bearing at the bottom of the distributor, where the oil pump drive engages it, is bigger than the car ones. Either bush it down, or use the truck dist. and pump and drive. It's 33/64",I think.

after reading an article a few months ago, in engine builder magazine, about metallurgy... i've decided using 30 year old cranks isn't a good idea, the thing is metal does age and weaken with age, cranks, even more so than things not seeing a lot of pressure... secondly you really dont know how the last owner of that crank drove the vehicle it was in.... 3rdly steel cranks tend to be more brittle anyways, which means it could already have a bunch of microscopic stress fractures running through it.... i've used plenty of old cranks and not had problems, but it does make you wonder sometimes.... personally if it can be fit in the budget, i'd prefer putting a brand new steel crank in there.... i know its expensive but it is some good insurance.... the billet steel cranks are obviously the best but also cost a lot of money, but the forged steel cranks are pretty good as well