I have a new to me 78 supercab with a 460 (D3V Heads) and electronic ignition. Was playing around tonight and decided to check the timing. Removed and pluged the vac advance, rpms at 650. It's set at 14+deg initial. However when I increase rpms it doesn't move or even drops a little. I tried it with vacuum connected and it goes over 30 with increased rpms. I should have mechanical advance - right? I would check, but have never pulled a distributor apart before. Is that safe to do with the dist installed. I don't want to loose some small part into the engine.
easy to check. just take the dist cap off and the mechanism is sitting right there underneatht the rotor and the reluctor wheel. it is two weights with springs attached to them. manually move the weights to see if it moves the plate. lost of the emission era dist don't have a lot of mech advance built into them and the advance is pretty small. most of the advance comes from the vacuum can.
you can get new springs to change the rate. the limiting factor is if you look you will see a square window with a tab thru it on the pickup plate. this limits how much advance you can get out of the dist.
do a google search on the Duraspark II distributor. should be lots of links showing a breakdown on this distributor.
Thanks guys. I was able to find instructions and took it apart. It looked decent inside, but was frozen stiff. Cleaned it all up, hit it with a little lube and put it back together. Seems to move freely now. Didn't have time to play with it tonight, but will check timing again tomorrow.