Have goggled this a bit and a little unsure on which is the best crank? Is it the 6 bolt or the 8 bolt 164 have both and when I do get around to rebuilding not sure which would be best. @Rob I thought you might have a idea or anyone got any advice.
My understanding is that they are essentially the same. I would chose the one that you have the a flywheel for.
I'm with Rob, I'm not aware of any other differences, so I'd find a flywheel and then use whichever crank suits the flywheel.
I think it was just a running change they made as they gradually worked towards the changes needed for 240 production.
Thanks for that, there were a few other forums were they seemed to favour the 6or 8 for one reason or another nothing real specific so thought I might ask the question
didn't The b20 bottom end change to different rods & bearings with the change from 6 bolt to 8 bolt fly? Dunno if I'm remembering right or if it applies to a b30...
I'm not certain either, but I don't think that's the case, I think the internals are all the same.
I know that a B23 crank can be sat in a B20 block and spun over and all the bearing journals are spot-on. Obviously it can't actually be used due to differences at the front end of the crank.
Maybe I'm thinking of gudgeon pin sizing changes...when I was mocking up a b20 turbo idea the b21ft pistons were a direct fit on 8 bolt crank'd rods, perhaps the m rods came in then?