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Full Circle crankshafts
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 Posted: Mon Jan 28th, 2013 11:32 pm
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Steve Welte
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I happened to notice a Full Circle West Bend crankshaft on Flea Bay. When I looked at the closeup it appears to be all epoxy to modify it. Back in the day I had a couple full circle Mac shafts that were filled with epoxy but had a machined metal band around the outside. I don't remember if it was steel or alum??? It just appears to me that epoxy alone wouldn't be a good idea. Is it being done differently today or maybe no one is really doing it?

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 Posted: Tue Jan 29th, 2013 04:57 am
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Bill Johnson
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Jim Ackerman said it would work but I wouldnt recommend it. Talked to him about 5 years ago about the process and he said dont bother with the alum rings today.

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 Posted: Tue Jan 29th, 2013 05:05 pm
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Steve Welte
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Thanks Bill. That is interesting. I know Epoxy has come a long way in 40+ years but still at 12,000 rpm I don't know. I did notice the epoxy appeared pretty clear where the old cranks were a greenish epoxy.

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 Posted: Thu Jan 31st, 2013 10:49 pm
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Alan E. Lidke
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I dunno. I wonder if some of the epoxy is really as good as it was back then. I quit messing with full circle cranks but I used to build them just as our shop did in the '60's using a BIG hose clamp silver soldered into a circle. It was especially nice if one had the slots in the clamp all the way because it permitted the epoxy to bond into the ring.

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 Posted: Thu Jan 31st, 2013 11:03 pm
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Sterling Brundick
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O. K. Here's where I really show my ignorance. Can someone post a picture of a typical crank and a full circle crank so I can see the differance and then be kind enough to explain what the functional differance is please. Thank you.

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 Posted: Thu Feb 7th, 2013 06:30 pm
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Mike Clements
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The function is to "stuff" the crankcase for a larger pressure differential. That ultimately forces more air and fuel into the combustion chamber for more HP. Kind of like running the super charger on overdrive.
My dad built my engines when I was a kid and racing the Mc's and 820's. He too used the round metal band that was lightly tig welded to the counter weight. He filled that open area with A-B epoxy and it really did bring the engine to life. The epoxy didn't last forever, so we called these "Qualifying engines".
I'm 62 now and my dad passed away 17 years ago. I miss him every day too. There are so many questions I would ask today of him. I wasn't smart enough to know what to ask while he was here.

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 Posted: Fri Feb 8th, 2013 01:06 am
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Dewey Weber
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Hey Guys

Im pretty new to all of this however what about a Gem Stuffer will that help

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 Posted: Fri Feb 8th, 2013 01:52 am
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Ted Johnson
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A bottom (crankcase) stuffer does help, but the difference between most factory stuffers and aftermarket stuffers isnt as great as the reduction in volume offered by a full circle crank. A full circle unit also reduces turbulence. In the early days of karting, guys stuffed the case with Devcon epoxy, stuffed the inside of the piston with cork saturated with epoxy, and built full circle cranks. I'm with Alan. I don't think even JB Weld is as good as some of the epoxies in the early sixties. We had a steel-filled epoxy caled Cipcobond that was almost black. When you filled a Mac third port cavity with that stuff, you better mean it to stay for a lifetime! There was an opaque white epoxy that was fantastic as well. I can't remember the name of that one. It worked for full circle cranks, but we also used a band around it. TJ

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 Posted: Fri Feb 8th, 2013 10:30 am
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Sterling Brundick
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Thanks Mike & Ted. Now I understand the purpose. But let me ask this question. Since you have filled in the "void" so to speak with solid mass, wouldn't you have less air in the chamber? Seems like the fuel volume would not change but the same volume would be forced through a smaller space. Is that correct?

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 Posted: Sat Feb 9th, 2013 02:36 am
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Tom Smith
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I was selling the full circle WB 820 crank. It's from a West Bend 820 Dave Bonbright ran with good results. Since nobody was switched on enough to buy it I think I'll trade Bonbright for it and switch the cranks in my 820.

Last edited on Sat Feb 9th, 2013 02:40 am by Tom Smith

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 Posted: Sat Feb 9th, 2013 03:16 am
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Steve Welte
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So Tom I didn't purchase as I don't have any 820's. So can you tell me if that is banded or not? That would be the crank I was looking at on E bay.

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 Posted: Sat Feb 9th, 2013 04:08 am
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Tom Smith
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no band

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 Posted: Sat Feb 9th, 2013 09:41 pm
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ralph hollinger
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I will be selling a couple 580's in the next several weeks. They are proto type engines built by an aircraft tool and research company in the 60's - they were the 580 kings in my neighborhood here in the Mid Atlantic where I grew up. One engine has an all steel full circle using a very interesting concept. Both engines have removable cylinder heads. Removable heads was their speciality and they perfected it over the years. Should I sell them here or on ebay??

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 Posted: Sat Feb 9th, 2013 10:17 pm
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Brad Beard
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We followed the Ackerman article in one of the kart magazines to modify a 91 when I was a kid. We did the full circle crank but without the rings. Bad idea. It let go the first pop out of the box and we were on our way to Comet to have it done right. I can still remember Diz laughing when we told him what we did to basically destroy a perfectly good Mac 91. Brad

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 Posted: Mon Feb 11th, 2013 10:28 pm
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Lee Williams
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The epoxy that Jim A. used for his cranks was either Hysol or a very similar type. It is still available today.

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 Posted: Mon Feb 11th, 2013 10:53 pm
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Brad Beard
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Seems like I remember it was DevCon, but it was 40 some years ago.............

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 Posted: Sun Dec 1st, 2013 04:29 pm
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Gary Haggar
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I just came across this artical on the full circle cranks and thought I'd add my 2 cents. I ran 820's for 3-4 years both strokered and with Akerman Full Circle cranks. At the time the Akerman cranks I bought were made up of epoxy with a metal band around them. Never had any probs with any of them coming apart in my 91a1's or 101 Mc's or my 820's. We milled the heads,shaved the flywheel, knurled the pistons, stuffed the front end with a GEM stuffer plate and mounted 2 big Tilotsen carbs on what was called a V12 manifold(an added 3rd carb in front in place of the stuffer plate for enduro races). Took up as much space as posible inside that engine keep her tight. Sometimes too tight. If one of them ever detonated it was a real mess. The sucker would fragment like a hand grenade:shock:. But my gawd would those things scream. Thanks you guys. You really brought back some fond memories of some of the most fun a guy could ever have in this life. Busting down the track/street race in my C open machine at near 100 MPH was such a rush. I dont think I ever got the chance to experience just how fast one of the C open (twin fully modified (strokered) 820's or Mc 101s) would go. I just know they were much faster than most people ever gave them credit for. I saw you guys mentioned Diz (Emerson Dizmore). I live down the the street from Comet Kart Sales today oddly enough.Bought all my jugs and parts there for years. Im 60+ yrs old today. But its good to see some of you never forgot what it was like back then before the Komets and B-Bombs replaced the Mc and West Bend Chrysler engines.

Last edited on Sun Dec 1st, 2013 04:34 pm by Gary Haggar

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