[Fot] TR Racing cranks- and another question?

[Bill Babcock]

It doesn't have to, the spacers just need to keep the rods from moving  
too far. They can be pretty loose, certainly looser than thrust  
bearing clearance. Still, I think it would work a lot better to put  
spacers in the pistons where the movement is relatively slow rocking  
rather than spinning. That's what we came up with for racing two  
stokes--no reason why it couldn't work here as well. I discussed that  
with Uncle Jack, but nothing came of it.

On Sep 12, 2008, at 8:06 AM, fubog1 at aol.com wrote:

> Two questions actually...
> 1) the spacers on the pin... does this not induce side thrust loads on
> the piston? This is not good.
> 2) if the BE is narrower, there is excessive cheek clearance. Again, a
> bad thing.
> I'm curious as to how this works in service...?
> Glen
>
>
> -----Original Message-----
> From: Larry Young <cartravel at pobox.com>
> To: Greg Solow <gregmogdoc at surfnetusa.com>
> Cc: FOT <fot at autox.team.net>
> Sent: Fri, 12 Sep 2008 9:47 am
> Subject: Re: [Fot] TR Racing cranks
>
>
>
>
>
> Greg,
>
> To get a larger radius on the crankpins, do you weld the edges and  
> then
> regrind? On my current engine, I welded the edges of the crankpins to
> reduce their width so they would accommodate chevy rods. I them
> reground with a larger radius to reduce the stress riser.  This is a
> cheap approach that addresses both weaknesses, rods and cranks.   
> Others
> on the list have used chevy or other commodity rods, but have used
> spacers at the wrist pin to center the rod. The only problem is that
> welding puts a lot of stresses in the crank and proper nitriding
> requires stress relieving.  The grinder had a hard time getting it
> straight.  He said it was out 0.022 the first time it came out of the
> oven.
>
> Larry Young
>
>
>
> Greg Solow wrote:
>
>
>
>
>
>  A good used crank properly race
> prepared, deep case nitrided and ground with the proper radii on the
> journals, is very reliable at power outputs of up to 16
> 5 hp as long as
> the revs are kept below 6800 rpm. The weak link in bottom end is the
> connecting rod. For use over 6,000 rpm they need to be replaced with
> steel billet rods.
>
>                                                             Greg Solow
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Bill Babcock
Babcock & Jenkins
Billb at bnj.com
503.936.7660
www.bnj.com

Editor
Ke Nalu e-Magazine
Paddlesurfing's Web Journal

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blog: www.ponohouse.com/ponoblog

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