You can also check this link for info on doing the DuraSpark advance. Your needs will vary but if you have a 13L slot & use base timing of 12 degrees you should have a total of 38 degrees at 2500 rpm. You can work from there with more or less. My dist was set on the 15L slot which I changed to 10L, The plate will have 2 slots. Each dist differs as to what the slots are & you will not know until you tear into it. While you do not need to remove the dist from the engine if you alter the slot to the other slot in your dist do not forget you will now be 180 off & you will have to at least pull it up & redrop it.

Carbed Ford Message Board :: View topic - The Ultimate Duraspark Ignition Timing Guide

 

A lot of little things come into play for total timing but the most important is going to be the fuel you run. With the price of it and the low milage our trucks get to begin with the temptation to run the crap is too much. If you run it you probably aren't going to be able to run much more than 32 total mechanical. I"d start around 10* initial and go from there, you might get it up to 12*. I'd try the 2 stock light springs first before spending any money, they more than likely will do just fine. The total mechanical is important to get right and maybe you might luck out and get a slot that will work but like I said be prepaired to have to adjust the slot some. There is no right or wrong way you just have to come up with a way to limit the arm to where you need it. This is a picture of a vacuum advance limiting arm I made.

 

Shouldn't you be able to adjust the vacuum advance with a Alan wrench to limit its travel?

What slot are you using on this dizzy? and what yr is it in?

 

Most, if not all, replacement Duraspark distributors will not come with an adjustable vacuum advance canister, you'll need to buy an aftermarket can like Crane's or Mr. Gasket.

 

Really?
I'm starting to wonder if i should just go the after market route.

 

Does anybody have any thoughts on the proform distributors?
They look like the stock unit but they say are blue printed for performance.
I've sent them a email asking for
More info on their product, but haven't heard from them since.

 

You will still have to custom tailor it to your specific application.