[Jonsey]

This car used to have the same engine with a much larger cam, TH400 transmission with 3200 RPM converter. It had the stinky idle and not great throttle response at partial opening, but never bucked at low speeds. An auto trans does hide a lot of these issues.

I had a chance to look at the timing this weekend. Warmed up, it had 14 degrees initial timing with 36 total by 3000 rpm. Another 7 degrees was provided by the vacuum advance at idle.

The chart with the MSD Pro Billet directions shows it should be providing 16 degrees of advance at 12 inches of vacuum. I'm not sure why I only get 7.

We swapped out the 23 degree advance bushing for an 18 degree advance bushing and moved the initial timing up to 18 degrees. Idle AFR changed to a 13.5 target. It runs much, much better. Almost no bucking down to 1500 RPM in first gear.

It looks like the MSD Pro Billet uses a GM points style vacuum advance unit. The Crane Cams 99600-1 is out of stock everywhere. Accel has a model 31034 that looks like it will work. The directions with that unit say it can provide between 5 and almost 30 degrees of advance depending on adjustment. I'll order of those and see if we can get a little more timing out of the vacuum advance.

It's amazing how much better it runs with just a little more timing. Thanks for the tips!