The Ford Barn - View Single Post - Timing issues, Bosch magneto/ laurel cylinder head

rotorwrench · 06-04-2022, 10:21 AM

Make sure the distributor rotor is timed to fire on the #1 cylinder terminal contact. Make sure the spark advance (magneto cam or interupter housing control arm) is set for the retard position. The engine will start with some advance. Many engines of this size will start around 5 degrees advance from TDC. The model T may start with more advance than that but I don't have the instructions for the model T engine.

These mags can be set for clockwise or counterclockwise rotation so a person has to set the distributor rotor for the proper rotation and observe that the interupter lever is turned the proper direction for advance and retard. It can be set up either way so the installer has to verify that it rotates the correct direction with movement of the lever. The installer also has to verify the the firing order for the other high tension leads is properly set. The mag can rotate either way depending on how it is set up so this has to be observed to get it right.

If the mag is rebuilt and fires on the bench then timing was likely the only problem. From there, it's all about fuel delivery and a proper mixture to start it.

06-04-2022, 10:21 AM	#20
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 17,409	Re: Timing issues, Bosch magneto/ laurel cylinder head Make sure the distributor rotor is timed to fire on the #1 cylinder terminal contact. Make sure the spark advance (magneto cam or interupter housing control arm) is set for the retard position. The engine will start with some advance. Many engines of this size will start around 5 degrees advance from TDC. The model T may start with more advance than that but I don't have the instructions for the model T engine. These mags can be set for clockwise or counterclockwise rotation so a person has to set the distributor rotor for the proper rotation and observe that the interupter lever is turned the proper direction for advance and retard. It can be set up either way so the installer has to verify that it rotates the correct direction with movement of the lever. The installer also has to verify the the firing order for the other high tension leads is properly set. The mag can rotate either way depending on how it is set up so this has to be observed to get it right. If the mag is rebuilt and fires on the bench then timing was likely the only problem. From there, it's all about fuel delivery and a proper mixture to start it.