I guess I have to do more homework cause now I'm really confused:
I thought the distributor on a 4 stroke spins at 1/2 the rate of the
crank since the cam gear is 2x as large as the crank gear. If the
distributor is spinning at 1/2 the rate of the crank, it seems like
there would be a spark (at a specific cylinder) every 2 rotations of
the crank. Where is the hole in my a**-backwords thinking?
This means the coil would send a spark every 1/8 of a rotation of the
distributor = 1/16 of a rotation of the crank (if you use my mixed up
reasoning above).
... I now see why there is a setting for # of cylinders.
What your saying makes sense though, because when I've got my
distributor in 180 degrees (like I did last month when I was putting in
an HEI), the motor will back fire. This means it's trying to ignite on
the exhaust stroke, right?
-alfie
Quoting zman <zman@gibbon.kungfumonkey.com>:
> On Tue, 16 Mar 2004 bigfred@unm.edu wrote:
> > Sounds to me like the tach is set up for a 2-stroke motor.
> > See if there is a way to configure it for a 4-stroke motor.
> >
> > If the tach thinks it is reading for a 2-stroke, it will show the
> same
> > number of RPM as there are sparks. So if the motor is spinning at
> 3000
> > RPM, the motor (since it is a 4 stroke) will be sparking every
> other
> > rotation of the crank or 1500 SPM (sparks per minute) = 1/2 motor
> RPM.
> > Since the tach thinks the motor is a 2-stroke, it will show 1500
> RPM.
>
> Actually there is no difference between a 2-stroke and a 4-stroke
> tach.
> Most all 4-strokes fire on both strokes, though they make power on
> only
> one. Where the 2-stroke makes power every stroke. The reason I said
> that
> it was most likely a 4-6-8 switch is because it reads it from the
> coil and
> not a particular plug wire.
>
> --
> Scott H. Zekanis
> zman@kungfumonkey.com
> http://www.rod-o-rama.com
> http://www.thehellbenders.com
> 1957 Buick Riviera Hardtop (2 dr., 364" Nailhead)
> 1959 GMC in Chevy Sheetmetal 1/2 Ton (235" Inline 6)
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