Big Picture: Trigger Offset and Advance
Posted: Mon Jan 10, 2011 4:32 pm
My 1985 CRX is finally starting and running well enough to worry about setting the timing. I'm using a stock but locked distributor for the signal to MS, which is controlling the timing.
I would just like to make sure that I understand the relationship between the trigger wizard, trigger offset, and advance as set in the tables.
The Trigger Wizard, in this instance, is used to equilabrate the VR signals coming to the MS from the distributor to the actual position of the number 1 cylinder.
It took 22 degrees in the trigger wizard to line up the timing light to the TDC mark on the crank pulley. Essentially, this means that the VR signal the MS receives is 22 degrees out of phase with TDC. It doesn't mean that the base timing is 22 degrees advanced. The trigger offset is not a component of the spark advance table, just a synchronizing device.
Stock base timing for the CRX is 16 degrees.
If I leave the crank pulley mark at TDC and don't set it to base timing mark, the cells in the advance table will be net of the missing base advance. So, if the relevent table cell was 16, the actual physical advance would be zero. If the cell was 14, total timing would occur 2 degrees ATDC.
I then reset the timing so the light flashes on the base timing mark. In this case, if I have the table cell at 16 degrees, the spark will occur 16 degrees BTDC, which is the base advance. If I have it at 14, MS will retard the signal by 2 degrees of rotation.
Right?
I would just like to make sure that I understand the relationship between the trigger wizard, trigger offset, and advance as set in the tables.
The Trigger Wizard, in this instance, is used to equilabrate the VR signals coming to the MS from the distributor to the actual position of the number 1 cylinder.
It took 22 degrees in the trigger wizard to line up the timing light to the TDC mark on the crank pulley. Essentially, this means that the VR signal the MS receives is 22 degrees out of phase with TDC. It doesn't mean that the base timing is 22 degrees advanced. The trigger offset is not a component of the spark advance table, just a synchronizing device.
Stock base timing for the CRX is 16 degrees.
If I leave the crank pulley mark at TDC and don't set it to base timing mark, the cells in the advance table will be net of the missing base advance. So, if the relevent table cell was 16, the actual physical advance would be zero. If the cell was 14, total timing would occur 2 degrees ATDC.
I then reset the timing so the light flashes on the base timing mark. In this case, if I have the table cell at 16 degrees, the spark will occur 16 degrees BTDC, which is the base advance. If I have it at 14, MS will retard the signal by 2 degrees of rotation.
Right?