My car has been a little sluggish lately, checked the timing only getting 24 total. This is an HEI distributor.
On the dyno I got my best power and torque with 28 total and my best idle and starting with 16 initial. As I'm on the edge of detonation I disconnected the vacuum advance. In order to get 16* initial and 28 total at 3200 rpm without the vacuum at idle, and keep my advance curve, I welded the distributor plate on the low side to keep the mechanical slightly on and have the desired 16 idle. Worked well and stopped the partial throttle up hill pings I was getting with the vacuum advance.The vacuum signal does not drop to zero on partial throttle pulls.
I checked the advance mechanism and everything seems to be in order, no rust or debris to stop it from reaching the previously set 28 degrees. I can see the springs going soft and getting more total or total at a lower rpm but can't think of why the initial would stay at the previously set 16 and the total would drop to 24. Any way the module would cause that? I've had a few that just stop working, like turning a light switch off one second working and the next junk, but never heard of one doing this.
