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Wedge [no this doesn't belong in the 'rumph forum]

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ChrisS

ChrisS

Jedi Knight
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I spent a little time after work today down in the machine shop with a spare crank I have. A couple of the journals were marginal for needing a grind so I didn't care to much about it. I set it up on the milling machine to try and wedge it myself, below is the result. I think I'll get it balanced next week. For those that care, with a 2' main / 1.625" rod journal I set it up will parallel blocks such that the bottom of the rod journal was 0.500" above the base on the main. I then cut down the crank until it was 0.425" above the main journal. I don't know if this is what APT does but it seemed to work out pretty good for me.

crank_end.JPG


crank1.JPG


crank1.JPG


crank2.JPG


crank3.JPG


crank4.JPG


crank5.JPG
 
I don't know nuthin' 'bout no crankyshafts...but it sure is purty. :thumbsup:
 
Looks good. You can do mine next! :laugh:

Seriously, that would take me all week to do.

I realize there's a weight reduction, but it's around a pretty small radius of the rotating member (as opposed to cutting metal off the outer edge of the flywheel).

What is the other advantage of wedging? Oil churning?

Are you planning on running a crank scraper?

I'm doing up my 1275 right now (for the A35), but it'll just be stock this year
 
It's more to move the counter balance away from the rod pin and cleaning up some of the shark edges /stress risers and less about rotating mass. I plan on getting a crank scraper as well. I talked with a local racer that helped fit / develop this one.
 
Just for grins and giggles please someone explain the reasoning behind all of this and the exact purpose of the scrapper. Is it to force oil down into the sump more quickly so it is available for the stroke?

Mark
 
To reduce oil frothing. Smokey Yunick did a very nice treatise on power loss and recovery. In his research he states he was amazed by the amount of oil foaming and frothing occurring inside an internal combustion engine.

So he started the quest of reducing oil frothing, to maintain oil lubrication integrity and to reduce "windage" losses as the crank, rods, etc. are whipping through foam.

For a good visualization go to the bobstheoilguy.com site and look up his Lucas additive section.

The less foam and froth you create the more power you conserve, the better your lubricant will last.

Years ago there was no such thing as oil splash shields, scrapers, etc... Now every single new automotive manufacturer that I am aware of uses them in their engines...
 
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