I have a 408 smallblock with an msd pro billet distributor. I bought the distributor to make it easy to tune for my application- no welding up slots or repeated disassembling to tune it.
I had a flat spot I couldn't cure at 2200 rpm. I tried switching to an air gap from a single plane, adding a 4 hole spacer, acc. pump tuning... Couldn't get rid of it.
Don's 10* mechanical advance bushing let me bump the initial from 16* to 24* while keeping the total timing around 34*. Not only did the flat spot disappear but I have better low rpm throttle response. My mini starter doesn't kick back or anything.
Hope this helps somebody else.
Kevin
