MSD Distributor Advance Bushings

[Stumper]

Just got done installing a smaller advance bushing in my distributor as I want to try lowering my initial timing back down a bit. I have not started the motor to reset timing yet and have to leave for the afternoon but wanted to pose this question .... in theory at least, do you think that going to a different size advance bushing will change the initial timing or just the amount of advance - or both?
I know I'll need to reset the timing but just curious what the theory is with these bushings.

:toothy9:

 

[fugly]

It changes the total amount of advance between base and all in- if you set it with the max the same as it was, your base will be lower

 

[Stumper]

That's what it appeared to do. Adjusted it a bit earlier and while my full stayed near 38 degrees the initial dropped "a bit". According to the chart the initial should have come in around 18 degrees with the blue bushing but it was more like 20 degrees. Just took it out for a short crusie - and the jury is still out ........