Distributor setup

Hello all what I am looking for is setting my Distributor advance curve.I have read some post on setting it to gain some power but no spec on whats the best.Its a stock 1985 2.5 xj carb 5 speed most of the time hwy driving at 70.timming set at 12. What should total advance be and at what rpm should total advance be in on both vac and mec .Just trying to get the most out of it.just rebuilt engine Any info will help

I have the same setup you have. I discovered that the vacuum advance can be adjusted. Pull off the vacuum line from the advance can, and use an allen wrench to adjust the internal spring pre-load that determines the vacuum point at which the advance changes. I don't remember right off hand the size allen wrench to use, or which direction to turn it, I should have taken some notes when I did this several years ago. It did make a difference on performance and fuel mileage, both for the better. You will have to experiment over several tanks of gas to find the "sweet spot." I set the initial advance by the sticker under the hood to get started. Hope this helps.

Thanks that will help some. I am thinking of installing an electric fan to help with power too and maybe a weber carb I know where a fu are that need rebuilt 32/60 I can make my own adaptors for it. Some where I seen apost about what they did for more power and one thing was setting up the curve but they didn't say what they set it to .

Another thing you can do is alter the mechanical advance curve. I don't think there are any kits for this, for the AMC distributor, but it is basically springs and weights inside the distributor, under the rotor. You can either install weaker springs, or add weight to the weights. I have done this to several Chevy distributors, it works real well.

Adjusting the vacuum advance alters the timing under different engine load conditions. Altering the weights and springs alters the timing curve under different engine RPM conditions. Unless you can find a source of reliable modification results, and can duplicate the modifications with a distributor machine, you will have to use the seat-of-the-pants dyno, and spend much time and gas experimenting.

Be aware, if you live in an emissions-test area, you may fail the emissions test.