I have a Prestolite IAT-4405 Distributor I got it NOS. I also found what I believe are some NOS vacuum advance cans for it. Standard VC-110 the vacuum advance cans showed up today. And they both have no travel? the stop on the arm is right up against the stop. If I add vacuum to the can the arm does not move. What am I missing here? There is no obvious way to adjust them like with a 68 Mustang 200 6L distributor where you turn a screw inside the can to adjust. Are both of these made incorrectly or what. One of the arms has 3.5 stamped on it the other has 7.5 on it. Any of you old school distributor guys got a clue?
Look real close and see if they were locked for shipping. I am just guessing on this but that is what I would look for.
Nothing inside which looks to be an adjustment. The advance that is in the distributor the stop is about 1/4"" away from the stop. The arm is in the orientation it fits into the distributor with. I car with a pair pf pliers pull the stop away about 1/16th inch on the one marked 7.5 and maybe 3/32" on the one marked 3.5
If mounted on the dist. with the arm hooked on the breaker plate,does this then move the arm off its stop & is it then able to move the arm or plate w/ vac applied ?
Arm has to travel toward the diaphram when vacuum is applied. I think they are faulty. The exact amount of advance & the inches of vac needed is, in my opinion, not as critical as the centrifical advance. Vac advance helps mileage when cruising. When you floor it there is almost no vac so it does not effect acceleration. Greg
Not Sure but I can't pull the arm out even if I use pliers to get a solid grip on it. they both have at best 3/32" of movement. I checked another new spare I have and its only got maybe 1/8" of movement. I think I am going to unweld the little mounting bracket so I can grind the stop back a bunch then weld a little tab on the arm with a set screw I can adjust the amount of travel with. I have four of these now that are all new. SO I can risk experimenting. I tried mounting one to a spare IAT-4405 distributor I have any yes it moves the plate MAYBE enough to change the timing 2 degrees.