[AT] Starting Issue with MH Pacer

[charlie hill]

Alan,  your comment raises a question I've wondered about 
many times but never asked.  Occasionally I run across a
distributor with a different kind of rotor button.  Instead
of having a simple brass rod that runs out and sweeps past
the contacts for the spark plug wires it has a rod that is
shaped like a sickle, a long curved L shaped rig that is close
to the contact points much longer, maybe as much as 10 degrees.
I have always wondered why those rotors are out there and what
their purpose is.  I think one of my D-14's has one.  I can't tell
any difference as far as timing goes but it should make a difference
of some sort.

Does anyone know what I'm talking about?  

Charlie

-----Original Message----- 
From: Alan Riley 
Sent: Tuesday, September 02, 2014 1:39 AM 
To: Antique tractor email discussion group 
Subject: Re: [AT] Starting Issue with MH Pacer 

Incorrect point gap will affect ignition timing.  When the points open 
with respect to crankshaft position determines when the spark is 
delivered to a particular plug.  Point gap determines the location on 
the ramp of the distributor cam lobe at which the points open.  

If they open further down the ramp from the peak of the lobe than
they should, then ignition timing is retarded since the crankshaft 
has rotated an additional amount before the spark occurs. 

Conversely, timing is advanced if the points open nearer to the 
peak of the lobe than they should.

Alan





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