[Henryat1140]

The reason for the test was to use the vacuum gauge to set the initial timing at idle.

We understand the way to do this is hook up the gauge and move the set screw on the side of the distributor upward, advancing the spark until a peak is detected, then move the screw back down to reduce the vacuum by 1".

What we found was there was a constant reading of about 14" when we started, and by advancing the screw we gained 1" of vacuum. At that point the screw was at the top of the slot and no further advance was possible.

We made a test run and the engine 'seemed' to be a shade happier, there was no pinging even though we tried to make it ping. We noticed a slight drop in engine temperature while running under normal conditions.

My opinion (not based on scientific evidence) is that the typical flathead as we use them could stand more advance. The fuels are better and the roads are better. Getting the engine to run at the proper advance point also helps it to run more efficiently and thus cooler.

Has anyone ever modified the top of the slot in the distributor so the adjustment set screw could be moved further up - thereby advancing the timing somewhat more? IS there any other way we should approach this? The distributor is a Ford genuine rebuilt which was sent to Skip H. for checking - he said it was OK.

Sorry for the long post -

Henry