Hi Guys and Gals,
The issue today concerns a 73 challenger 340 bored to .060, Holley 6 pack carbs, and a Lunati cam 235/285. It has ceramic coated long tube headers and the other day I attached air/fuel sensors in both collectors and adjusted the carbs to get 13.5 to 14.2 readings, so it runs sorta ok, but not really.
I got out the timing light and the vacuum gauge tonight and got some rather interesting readings. At idle, about 1050 rpm, I get an initial timing reading of 30 degrees. The dist vacuum says no vacuum.
I crank up the revs to 3000, now I get a total advance of 70, 50 at the crank and 20 vacuum. When I hook up all of the vacuum lines like they should be, I get a total advance of 70 at 3000 rpm.
So I break out the calculator, pound a few buttons and I think I get 70 total advance at 3000, with 40 of that being mechanical from the stock Mopar distributor. I do not have any MSD units or anything like that in the mix. The electronic module is black with a gold heat sink and has a mopar part number. If this is important, I can get the part number from the module.
I have read that Mother Mopar says the advance should be about 35 degrees. I have also read that Chryco hates vacuum advance.
![hornet :poopoke:](http://www.cuda-challenger.com/cc/Smileys/default/hornet.gif)
I have no problems capping the distributor vacuum port on the center carb. And the outboard cards, well never felt them kick in.
So my question now is what to do next. If I want to get the advance down to 35, I can turn the distributor and lower the initial advance. The cap the vacuum and leave the mechanical alone, meaning no spring changes. When I get it to this state, I then break out the air/fuel sensors and get as close as I can to 14.7? Or do I just turn the dist until it 'feels' right?
Am I on the right track? Comments/suggestions please.