Timing is Everything

And the Mustang didn't have it. I went to an 1/8th mile track last weekend, and despite changing the springs in the carburetor to a more conservative profile, it still didn't run right. That left the finger pointing squarely at the distributor. Sadly, my timing light was busted, and I didn't have the components to change the timing curve. I limped it down the track a few times, and then brought it home. It had amazing power once I hit around 4k, but nothing until then. Several people commented that they could hear it come alive about 200 feet down the track. Unfortunately, a lot of time had passed until then, which resulted in low ETs.

An Explanation on the MSD distributor:
Its a beautiful piece of simplicity. Other than the traditional turning of the distributor to set the timing, there are only 2 other adjustments; springs to control a set counterweights which spin out as the RPMS increase to advance the timing, and a bushing which stops the advance. It has a magnetic pick-up which sends a signal to the MSD box 8 times every revolution. Add a cap and a rotor, and you have it.

My distributor was set with springs too stiff, so the advance wasn't occurring fast enough. Also, the bushing was thick, so the total advance was minimal. I had to buy a new set of springs and bushings ($12.99) as well as a new total advance timing light ($49.99), as mine quit working.

The distributor was originally setup with 2 blue light springs and the black (largest) stop. I replaced one spring with a lighter silver spring, and replaced the stop with the silver one, which is the second smallest. I re-timed the distributor so that it has 15 degrees of advance at idle, and 36 degrees at 4,000 RPM. These two numbers are easily established by turning the distributor and setting the stop bushing. The key is going to be the spring rate; or the rate at which the timing advances from 15 to 36. This was a best-guess setting, and i can adjust further when I go to a test-and-tune. I will be monitoring my spark plugs closely to make sure I wont be running too hot, but the 15 degree idle and the 36 degree total advance were recommended to me by several people. If this timing works out, I should be able to make the carburetor mapping more aggressive. I really just need to get to the track and get a lot of runs to see what works.