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Ignition Timing

Submitted by andy_withers on Thu, 21/07/2016
Forums
Commando

I'm trying to do the timing on my contact breaker system on 72 commando. Contact breaker have been adjusted to 15 thous, TDC, auto advance locked, back 28 degrees. But when you need to adjust each contact breaker separately to the point of opening they will not adjust by moving the contact breaker plate or the individual contact breaker plate. Does anyone know why this will not happen? Can the auto advance be put in wrong?

Submitted by hans_taylor on Thu, 21/07/2016

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Hi Andy.

Presumably these are new parts ?

You should adjust the gap when the cam is at its highest lift, ie on the heel mark.

Then when you set the timing, by turning the engine you should get the heel mark just beginning to open the points at about 28 deg. Then adjust the points with the small screws. If the points will not open, then either you have the wrong advance cam or the heels of the points is worn down. I think !!

Submitted by jonathan_soons on Thu, 21/07/2016

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Previously andy_withers wrote:

I'm trying to do the timing on my contact breaker system on 72 commando. Contact breaker have been adjusted to 15 thous, TDC, auto advance locked, back 28 degrees.

This is a small quibble but all manuals (for just about any engine) recommend turning the crankshaft forwards, either with a spanner on the crankshaft or with the rear wheel, so as to take up lash in gears and chains.

Submitted by andy_withers on Fri, 22/07/2016

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Previously Hans E Taylor wrote:

Hi Andy.

Presumably these are new parts ?

You should adjust the gap when the cam is at its highest lift, ie on the heel mark.

Then when you set the timing, by turning the engine you should get the heel mark just beginning to open the points at about 28 deg. Then adjust the points with the small screws. If the points will not open, then either you have the wrong advance cam or the heels of the points is worn down. I think !!

Hi Hans

The parts are all original, well not new. I set the points on the heel marks, haven't checked the heels of the points to see if they are worn.

Cheers

Andy

 


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