On Mon, 21 Jul 1997 20:17:15 -0400 Trevor Boicey <tboicey@brit.ca>
writes:
>Ulix Goettsch wrote:
>> I thought it was overADVANCING that caused hot running.
>
> This is my understanding as well, both from reading
>and personal thinking.
>
> I am very sure of the graph that shows advance versus
>power, because it's always a tradeoff of power versus
>melted pistons from the heat.
>
>--
>Trevor Boicey
>Ottawa, Canada
>tboicey@brit.ca
>http://www.brit.ca/~tboicey/
>
I don't have any "scientific" evidence of over heating caused by
retarded timing, just personal experience.
Once in my jaded youth, I was riding with several friends on Harleys,
and my Panhead 74 had the simple manualy adjusted advance/retard. In my
case, it was held at full advance by a spring, which was unhooked for
starting purposes, and then re-hooked when running. That evening, the
spring broke (unkown to me) and my timing gradually retarded. I didn't
suspect any thing, probably haven just rolled a bit more throttle in
without thinking when the power went down, when a buddy pulled along side
and frantically started pointing at my exhaust. It was glowing cherry
red!. As I looked down, I also saw the broken spring, and quickly pushed
the dizzy to full advance, Within a very few minutes, the pipes where
back to normal
I can only surmise why the engine runs hot with retarded timing, as
being caused by the delay in igniting the mixture somehow allows the heat
generated to be, to a greater extent, passed through the exhaust port
without producing useful work (pushing the piston down).
Again, I don't know why, I just know it does.
Rick Morrison
72 MGBGT
74 Midget
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