On 8/29/2010 3:17 PM, fpspitfire@comcast.net wrote:
> Scott,
>
>
>
> I'm with Rick on this one.B I've never used or had a double row timing
> chain.B They are more than double the rotating mass.B why spend all that
> money to lighen the crank and rods only to bolt it back on the front of the
> engine.B While I agree the degreeing in of the cam is easier with kent
> adjustable, it just isn't worth the cost.
>
>
>
> I've never had a timing chain or gear failure...and I can't think of a
> spitfire racer who has.
>
>
>
Umm, technically, the only rotating mass added to the crank is the extra
row of teeth on the crank chain drive, so the additional amount is
actually rather small (taking an extra ounce or so off the periphery of
the flywheel would more than compensate). The chain isn't considered as
part of the rotating mass since it's an independent member which both
slides and rotates on its own (at a much lower rate than either crank or
cam), and the cam is operating at half speed, so mass effects due to
rotation are quite a bit less than for the crank assembly. The dual
chain does create a bit of additional frictional drag, so it would
consume a bit more power.
Still, I agree--if reliability is not an issue, and the cam can be
properly degreed without an adjustable sprocket, why go to the
additional expense?
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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