sb tuning problems

If you take it to the track, the dyno tune may not be the best tune up for the car. Seen this a bunch of times. Advance the timing 2* and see if MPH picks up. I fit does, the dyno tune is off because it didn't load the engine the same as the car.

MSD does not provide a bushing with less than 18* advance. That's why I made 14 and 10 * units. If you want to straight up hillbilly engineer a bushing, get a piece of .500 stock with a, IIRC, .187 hole in it. Jig it up in a drill and use a file to reduce it to about .405 od. Cut it off, flatten two spots on either side with same file... done.

IMHO, you can set the timing wherever you want, it won't run best with anything under 20 initial.

Simple test. DO NOT DRIVE THE CAR AFTER DOING THIS!!!
Start car, get it warmed up. Twist distributor a little CCW, if it picks up RPM it WANTS the timing. Reset idle and do it again. You may actually be able to get the carb under control doing this. Shut it off and try to restart, if it drags the starter badly, turn distributor clockwise a bit, try to start again. You want to find the point that the engine has as much initial timing as the engine wants or the starter can handle when hot. Any less and the engine isn''t as happy as it could be.

Do the math with your current 32* total number and that's the bushing you want. You have to work within the mechanical parameters of the distributor and bushings available. Once you get the correct bushing in there, then go drive the car.

I wouldn't waste my time with a 14* bushing! Get a 10*.

Timing FIRST, then mess with the carb settings. I wouldn't touch anything regarding the secondary plate opening until you have the idle timing sorted out. It will run entirely different once you give the engine the initial timing it wants!