Did BMS make a 3.06" stroke narrow journal forged crank?

[86brick]

Topic pretty much says it all.... I was told they did make a 3.06" stroke forged crank, but I haven't actually seen or heard of anybody using one so I was just curious.... Guess if they did these must have been used for the Indy motors, but I'm also curious if they were only wide journal or if they actually made them in narrow journal as well....

TIA

 

[KendallF]

Buick made raw forgings. They were finish ground by a number of companies so you will see all sorts of combos regarding width and stroke.

I would say that the vast majority of short stroke (3.06" and shorter) cranks were made for Indy/road race applications and used the wide long rods. In general, the early cranks were narrow journal and most later cranks were ground to wide journal specs.

I have seen several 3.06" wide journal; I also currently have one that's something like 2.75" wide journal. The crank in my motor is a 3.632" narrow journal.

 

[86brick]

Thanks for the info Kendall!

 

[John Wilde]

Kendall is the man!

 

[TurboDave]

These are Diamond, Muldex and LA Billet, but are a few examples of the really short one's.

http://www.musclemotorsports.com/musclemotorsouth/v6-engine-parts-buick-cranks.html

 

[1320n10]

Brick i have a brand new bms/moldex 307 narrow journal crank that has rolled fillets on both the mains and rods. So yes there were some finished with the narrow journals.

 

[86brick]

Dave, thanks for the link to those cranks.... Wow a 2.66" stroke crank! The shortest I had heard of was a 2.85"...... Cool stuff!

Walt, do you plan on using that 3.07" narrow journal in a stock block motor (say for TSM) or a Stage motor?? There's a guy down here that has one of these short stroke narrow journal cranks (I'm not sure of the exact stroke) and he plans on building a destroked 109.... I'm very interested to see how a destroked 109 would run (some say it's a dumb idea others seem to think it could be a good one).... Guess we'll have to wait and see

 

[1320n10]

Brick the me-r has only been tested on a ecm bench to 65-to 6800 I think with the 307 crank you would have to rev it to 7500 or so. Hopefully i will have a moldex 3.560 and an la billet 3.590 soon. One needs to stock pile this stuff when the price is right!!!!

 

[ijames]

Originally posted by 1320n10
Brick i have a brand new bms/moldex 307 narrow journal crank that has rolled fillets on both the mains and rods. So yes there were some finished with the narrow journals.

This is the first I've ever heard of a bms crank with rolled fillets. I'm pretty sure that they would have to be rolled after the raw forging was rough machined but maybe before the journals were finish ground to size. I don't see how Buick could roll them on the raw forging given the tremendous range of final strokes that people used. So who rolled them, and how much did it cost? Or perhaps these aren't rolled but had the grooves machined in (which isn't nearly as good)? Inquiring minds (okay, me at least ) want to know.

 

[1320n10]

Carl all i know is it is a bms forging that was finished by moldex. I have a 3.635 bms crank that has no fillets and the 307 sure looks just like a turbo crank on the journals.

 

[1320n10]

Originally posted by 1320n10
Carl all i know is it is a bms forging that was finished by moldex. I have a 3.625 bms crank that has no fillets and the 307 sure looks just like a turbo crank on the journals.

 

[TurboDave]

Originally posted by 1320n10
Carl all i know is it is a bms forging that was finished by moldex. I have a 3.635 bms crank that has no fillets and the 307 sure looks just like a turbo crank on the journals.

I'm wondering if someone just "cut" those fillets in? Actually rolling them would have been a stupendeously expensive operation on a "piece by piece" basis (as apposed to mass produced, same stroke cranks).

 

[ijames]

Thanks, Walt. Dave, that's what I was thinking, that they were just machined in.

 

[1320n10]

I will clean some of the cosmoline off one of the journals near the edge and see if i can shed any light on this. If does not really matter but now you have me curious.