Chaps,
I have my engine on the bench being rebuilt. The bottom end is complete including the magneto. The cylinder barrel is fitted but not the head. I thought I'd try setting the ignition timing before the head was fitted. I started out by just using my dial guage but I found it was not easy getting the before TDC accurate while fiddling with the magneto.
I made a bar from 10mm x 20mm steel stock with two large holes to allow a couple of head bolts with spacers, (also known as 1/2" sockets) to secure the bar across the cylinder bore. The bar also had a smaller bolt threaded and locknuted in the centre.
I set up my dial gauge so it touched the piston crown and turned the engine backwards until it measured the correct distance before TDC. The small threaded bolt was turned down to just touch the piston crown and locked up. This allowed me to take the engine back and then forward, (taking up gear slack) to stop at exactly the right place.
I wedged the loosely fitted A&R unit open to the fully advanced position and checked the points gap was correctly set.
Next I connected my digital multimeter, set to ohms across the contact breaker points. When the points are closed the resistance of course is zero. The mag was carefully turned until the points just opened, indicated by the resistance changing to approximately 0.5 Ohms.
I tightened up the A&R unit and ran the whole process again to check all was ok. Jobs a good'n
