The Stovebolt Site Forums The Shop Area Engine Shop Vacuum advance

The vacuum advance went in my 1953 235. We found a donor one from a 58 (I think) but I want to know of its compatible or the range of years that would be compatable.(ie.same angle of advance).

They might be different, and the difference might make a performance difference, but I doubt that - I have used a 1960 unit on a 1954 truck.

Is the 58 advance passenger or truck?
The passenger car advances are angled to clear the motor mounts.
Although there may be a slight difference in advance between the two,if they are both passenger car advances you can change the springs between the two,other than that it should work.

Since the vacuum advance only functions at very light-throttle cruise, it's pretty forgiving if it's a degree or two off. As soon as the throttle gets opened to accelerate or pass, the extra advance from the vacuum unit goes away and only initial and centrifugal advance is in play.
Jerry

I usually just run without a vacuum control like the larger trucks did. More advance at light throttle is supposed to help fuel economy, but I can't notice the difference and the vacuum control is just one more thing to cause trouble. Of course, I drive these old things like we did 50 years ago. Either full throttle or coasting.

Available from several vendors:

http://www.classicparts.com/1937-62-Vacuum-Advance-6-Cylinder/productinfo/83%2D274/#.VvvPtfA8KrU vacuum advance

Can we "rebuild" an advance ourselves?? Whats the best way to test an advance that is not on the vehicle?

...don't meant to hijack post but maybe its appropriate with this thread?

Make sure your bracket is compatible with the vac advance...

Some use a small step bolt, some use a tang, and some are angled as stated above

It would be hard to rebuild with out special tooling.
As far as checking condition. The main thing that fails is the diaphragm. If you have a Mityvac you can check for leaks in the diaphragm. Or the old fashion way is to suck on it with your mouth and then put your tong over the hole and see that it holds vacuum.

Back when most mechanics were smokers, we would blow a puff of cigarette smoke into the nipple. If smoke came out around the operating rod, the diaphragm was bad.
Jerry

Thanks... Jerry, since I don't smoke I'll have to get my 83 year old father in law to blow a puff into it. He takes his oxygen mask off long enough to puff a Pall Mall....not kidding!

I cold-turkey stopped smoking (3 packs a day) in 1977, Jerry

I would also have a hard time finding a friend to do it for me.

When I walked into an emergency room with chest pains about 15 years ago, I left half a pack of Winston Lights in the console of the Cadillac I was driving. I was in the process of having a heart attack. Two stents and a bunch of cardiac rehab made me make some pretty drastic lifestyle changes. The car is parked out in the pasture now, so if I ever really need a smoke, those cigarettes are still there! I kinda doubt that's going to happen, though!
Jerry

I ran on a 3000 mile trip with a failed Vacuum advance on my 3800. It had an off-idle hesitation that was annoying but I figured I could live with it. What I didn't realize was that running at light throttle and retarded timing raises exhaust temperature, which overheated the exhaust manifold and burned out the manifold gaskets and the exhaust pipe flange gaskets (Fenton). I had to fix it on the street in front of my sister's house in Salt Lake City in the snow in early November, which was a pain. NAPA had the gaskets and the advance unit and I bought both. I could have saved myself a bundle of trouble by replacing the Vacuum advance right away.

Alvin- a friend & I have not abandoned rebuilding a vacuum advance, but the attempt was pretty much halted 2 years ago as soon as I bought one for $30...

Brad

Thanks Brad. I have two so I'll give them Jerry's "smoke" test when I find someone who smokes.
(Pa in law went home today)...not sure for how long?


Edit: if mine is bad I'll take one apart just for the heck of it. I like to see how things work.

Can you apply some vacuum to the outlet and see if it holds to test them out?

The little hand-pumped MityVac unit is the best way to check any vacuum operated device, and it doubles as a very effective brake bleeder with the right accessories. Cheap on Ebay, also!
Jerry