Larry Mac,
You have to realize that I am a "seat of the pants" guy. For me, timing
settings I use are what work for me...I have found that just about every
engine has its own timing requirements. The ability of the cylinder to
fill has much to do with the timing required, as does combustion chamber
design, compression ratios, fuel quality, engine temp, etc.
I know that retarding the timing on the top end in the quarter mile is a
trick used by some...the old dual point distributors were often set up
to switch point sets at the end of the run to retard. It seemed to be an
advantage. I suspect that the timing was being run a bit advanced in the
lower end to improve acceleration, but when the engine was loaded
heavily at the end of high gear, the retarding prevented detonation. The
same idea could be employed at the salt on long runs.
I have run the high speed by-pass system in the past with good success
and at other times with not so good success. It has to be tailored for
your application. I now have a diaphragm valve with a jet box to control
how much is by-passed. The fuel requirements diminish as the engine goes
above peak torque because the engine loses volumetric efficiency. I have
just installed the high speed by-pass for the coming meet. In evaluating
the results of Speedweek, I found that to make it run on the top end we
had leaned the engine. In the process, we killed the low end
acceleration. With the engine on the rich side, we had a 215 & 213
quarter. After leaning, we had only one 213 quarter, all others were 210
or below.
I am sure that Dave, or others, can chime in here with a more technical
synopsis, but this is what my experience has shown me on the subject.
Tom, Redding Ca - #216 D/FCC
LGMCAFEE@aol.com wrote:
> This is something I don't understand. Why is the timing retarded on the top
> end? Does the temperature in the cylinder have something to do with it? And
> also in drag racing they starting leaning out the fuel on top end do any of
>you
> guys do this on the long runs?
> Larry Mac
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