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Re: Dwell angle

To: Phil Nase <nase@ptd.net>, spridgets@autox.team.net
Subject: Re: Dwell angle
From: "Robert E. Shlafer" <pilotrob@webtv.net>
Date: Mon, 12 Jun 2006 13:44:24 GMT
Point gap should be .015 and/or dwell 60
degrees. When this is correct, timing can
be set.

Since you are running a "286", it might be
fair to say the compression ratio is (hopefully) 9.5-1 or greater for the sake
of low-rpm trapping efficiency (reasonable low-end torque)?

When trapping efficiency is low, more timing can be tolerated (as in vacuum 
advance in the partially filled cylinders
as low rpm or light throttle "cruise", 
fr'instance. What static CR are you running
Phil?)

Thus, your motor can actually handle a bit
more and a faster rate of advance (even
at 9.5-1) than stock until the motor "comes up" on the cam (cylinder filling 
increases) at which point you'll want to "slow" the advance rate and in 
consideration of today's garbage octane hi-test (you are using the highest 
octane unleaded premium you can find locally,
of course!:), limit it to 28-30 degrees or so
as well.

Let's say something like 28 degrees total using 91PON or maybe 30 using 93PON. 

An engine "running on" after electrical power to the plugs has been removed is
normally a sign of too much initial advance
OR insufficient octane for the initial ign. advance setting (all other things 
equal).

I noticed this (run on) in my buddy's stock AH 3000 Mk3 while driving it 
yesterday after a hard country road run. A 
quick fill-up with Citgo (93PON) solved
the problem. He'd been using mostly
mid-grade "89" and occasionally "91" which
simply is not sufficient and most especially
so in warmer ambient temps.

In your case Phil, in consideration the "286" cam, using a slightly colder 
spark plug can help assuming the plug is not too cold so as
foul in light-load low rpm operation. Here
again, a higher than stock CR will be helpful
in the latter respect.

Cap'n Bob
Basic Frog

Cap'n. Bob      '60 :{)




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