WTF is with this crank sprocket?

[roostwear]

No pic (just a drawing), but i'll try to explain as best as I can. I got the crank and pistons assembled in the block Friday, and before installing the cam, I test fit the crank sprocket. Goes on a little looser than I'd like, and when it's in position against the back shoulder of the crank, it's loose against the key. The crank snout on this crank (don't remember on any of the other 390's I've had) is turned down about .030" right next to the shoulder, so that when the sprocket goes on, it barely sits on the machined pad. The bevel on the inside of the sprocket is also quite deep... far deeper than it needs to be to clear the radius at the back of the crank.
Anyone have a 390 crank they can check to see if the snout is machined wrong, or if I have too narrow of a crank sprocket?
http://www.roostwear.com/stevens/crank.jpg

[058]

I have some FE cranks, I'll check them out when I get into the shop sometime today. That reduced diameter does not look like something that was done by the factory. Do you know any history of that crank? Machined for a gear drive perhaps? A quick and dirty fix would be to turn the sleeve down to seal diameter size and weld the sleeve to the crank sproket so the sleeve would drive the sproket and use the extra surface of the crank key.

[roostwear]

No history on the crank. It looks like factory machining as the key extends back toward the shoulder past the machined pad. I just can't figure out why it would be turned down under the pad OD where the sprocket sits. Dumbass me tossed the old set already..... :cry:

[roostwear]

Well, spoke with my machinist and I've got a new crank coming with ANOTHER new bearing set. :mad:
Good thing I've been able to reuse 7 rods from this engine...... :cry:

[058]

I looked at a half dozen FE cranks and none had anything like what you described. Wonder if that was done by some "machinist" with a better[?] idea. :rolleyes:

[v-drive]

. Wonder if that was done by some "machinist" with a better[?] idea. :rolleyes:
I really hate those better ideas sometimes..........
:coffeycup :D v-drive

[roostwear]

The concensus is that in the past, it sheared a key and the sprcket spun on the snout. I'm not ignorant enough to just reassemble it as is, so the new crank goes in tonight. I guess sometimes ignorance IS bliss, but if replacing the crank now keeps me from getting towed in later, it's worth it.

[wideopen545]

i know this may be off topic
iam looking for a crank pulley for a 460 bbf single grove it needs to be a small diameter 5 1/2 in
i have a 10 and its turning my alt way to hard we have broken two already
thanks for any help tim
540.871.4833

[058]

i know this may be off topic
iam looking for a crank pulley for a 460 bbf single grove it needs to be a small diameter 5 1/2 in
i have a 10 and its turning my alt way to hard we have broken two already
thanks for any help tim
540.871.4833
A small pulley on a 460 is gonna be tough, most of them used the big drive pulleys to keep the accessorys turning faster. IMO this is something you will need to adapt from another engine or make a pulley. BTW, 5.5" might be too small, I made a 5.5" drive pulley for my Lavey-Craft and the alt. will not begin to charge until the crank rpms reach about 1200-1400 rpms.