Basics question about ignition timing and dwell relationship
 

Can anyone please explain if changing ignition timing (moving the distributor) also changes dwell?

In other words do I have to check dwell before and AFTER setting ignition timing?

Thanks in advance

Dwell changes timing, timing doesn't change dwell. You always do dwell first then set timing.

Here's another way to think about it: when you adjust dwell, it makes the points open earlier or later and stay open shorter or longer, which changes when the spark happens, hence changes timing.

When you adjust the distributor location, the points gap doesn't change.

rwest, thank you for your reply.
Very clear and precise...

You're welcome and thanks for the compliment!

I always knew the answer, but the why never occurred to me until I thought about your question and bingo, now I know too.