Don't forget to disconnect the vacuum advance
Mel (still looking for my elusive '59!)
----- Original Message -----
From: <dardal@xxxxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Sunday, January 12, 2003 12:33 PM
Subject: Re: IML: How to use a timing light
> Quoting Kevin Pacheco <kevin50187@xxxxxxxxxxx>:
>
> > Where are you supposed to set the mark to? theres a metal strip that
> > has
> > markings on it, but not sure where to set it.
> > Im using 91 octain and the elevations is over 7,000
> >
> > Kevin Pacheco 71 IMP
> >
>
> This sheet metal piece has some markings on it. There is a zero in the
middle,
> and then if I recall 3 marks from each side, 5 degrees each. So, you have
> reading resolution of 15 degrees befrore and 15 degrees after TDC.
>
> One of the cables of the timing light goes around the plug wire of spark
plug
> of cylinder number 1 (I think that's on the driver side, the one up front,
but
> check to make sure). With engine idling, aim at the harmonic balancer,
the
> little disk of about 1 inch thick that's rotating under this sheet metal
> piece. You will see a little horizontal groove on the harmonic balancer
> flashing and appearing motionless. If the little line is below the zero
mark,
> that means you are before TDC (which is where you should be). Now, if you
> loosen the distributor and rotate it a little, you will see this mark
moving up
> and down. When you rotate the distributor clockwise (the little vacuum
advance
> module is moving towards the front of the car) you are advancing and you
will
> notice the mark is dropping.
>
> What is the optimum setting for your car? Keep on advancing till you hear
the
> engine pinging (on a fully warmed up engine). Dick B. suggests to test
for
> pinging at around 30 mph on D, by pushing the gas on a medium to light
> acceleration. I do it differently. Since my cars are slightly modified,
I
> never hear pinging in that condition (unless the timing is way too
advanced).
> I do a WOT acceleration throughut the rpm range of the engine w/ 1st or
2nd gear
> (from 2000 all the way to 4500, no reason to rev it further if you are
trying
> to detect knock). If you don't hear any knocking, advance some more,
> regardless of what the timing light says (the more you advance, the higher
the
> performance and economy, and the lower the exhaust temperature). When you
do
> start hearing the familiar pinging sound, retard a hair (say one or two
> degrees) and leave it there. Use the timing light to record this
"optimum"
> setting, so if you have to mess with the timing again, you won't have to
go
> through all that. Its possible that in the summer you may have to retard
a
> hair more. The hotte the engine, the more it tends to ping.
>
> Beware: some real low compression ratio engines that have no carbon
deposits
> (I don't think the 71 is included, I think the 71 has close to 9 which is
> almost healthy) may never knock, especially when premium gas is used. If
you
> use the above technique, you may end up advancing way too much, which will
be
> beyond optimum. One of the symptoms for this case may be hard starting.
>
> D^2
>
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