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Speed,Combat,Scale,Racing => Carrier => Topic started by: bill bischoff on October 09, 2011, 12:48:12 PM

Title: "trick" for rear intake engines
Post by: bill bischoff on October 09, 2011, 12:48:12 PM: In recent posts I have mentioned that rear disc valve engines can be made to run backwards by assembling them "incorrectly". I just came across an article I published in the NCS newsletter in 2000. I thought it might be of interest.
Title: Re: "trick" for rear intake engines
Post by: Wayne J. Buran on October 09, 2011, 02:31:28 PM: Bill, I knew of the rear intakes being reversed however it was the standard front intakes that drove my question.
Thanks for the article.
Wayne
Title: Re: "trick" for rear intake engines
Post by: john vlna on October 09, 2011, 06:42:01 PM: Wayne
Some Front intakes can be reversed in the same way, the K&B with a bolted front end for example. Mounting the engine can get weird though
John
Title: Re: "trick" for rear intake engines
Post by: Wayne J. Buran on October 10, 2011, 04:32:36 AM: I understood that also, its the one piece case engines I was questioning. No source around here for that crank work.
Thanks
Wayne
Title: Re: "trick" for rear intake engines
Post by: john vlna on October 10, 2011, 11:45:28 AM: Wayne,
Yeah if it is a one piece case you have to have a LH crank, What motor is it?
John
Title: Re: "trick" for rear intake engines
Post by: Wayne J. Buran on October 10, 2011, 06:04:31 PM: Irvine .36 ABC Red Case
Wayne
Title: Re: "trick" for rear intake engines
Post by: bill bischoff on October 10, 2011, 09:08:17 PM: Wish I knew a source of custom crankshafts. Anybody know anybody who makes cranks?
Title: Re: "trick" for rear intake engines
Post by: Mike Greb on November 16, 2011, 04:14:01 PM: I have made LH cranks for my own use. What a PIA. I think i counted 15 setups to make a crank.
Title: Re: "trick" for rear intake engines
Post by: Tim Wescott on November 16, 2011, 07:08:06 PM: Quote from: Mike Greb on November 16, 2011, 04:14:01 PM
I have made LH cranks for my own use. What a PIA. I think i counted 15 setups to make a crank.

??

1: Chuck stock in 3-jaw, turn & polish bearing surface, prop mount, prop shaft (or hole for same), and front face of crank
2: Turn, wrap beer can around bearing surface, drill hole for intake
3: mount in offset holder, put holder in chuck (maybe swap to 4-jaw to dial in the stroke), turn pin and counterweight (thunkity thunkity thunkity)
4: Mount on V-block, carefully align crank pin, drill/mill/whatever the intake hole. Mill flat on prop mount if that's what floats your boat.

If you're not going to heat treat and a D-shaped prop drive is enough -- you're done and I'm confused. Even if you are heat treating then I come up with two more setups (one to finish grind the bearing, and one to finish grind the pin), and I'm still confused.

Granted, as wannabe machinists go I'm a lot more "wanna" than "be". So I'm not criticizing -- I'm wondering what the other 11 (or 9) setups are?
Title: Re: "trick" for rear intake engines
Post by: Mike Greb on November 17, 2011, 04:52:05 PM: It was a long time ago when I made my cranks. I rough turned the shaft and crankpin on my cranks because I was going to heat treat them. I think the way I did the counterweight took a couple, a couple for the intake timing port. These were produced on clunky machines and required a lot of messing around to get the parts finished . Maybe not quite 15, but a bunch. If these had been more that one off projects, I might have become more efficient.

I don't know if they are still available, but os made a left hand version of their 40 sf. That crank fit the os 40 and 46 sf and fx, and maybe some of the china os clone motors. Again that was a long time ago. One time I bought one of those cranks and a os 46 sf and had the crank installed before I left the hobby shop. Talk about voiding the warranty in a hurry!