Which vacuum advance unit to get?

['67Satellite]

The diaphragm on my vacuum advance control is broken. Looking for a replacement, I haven't really been able to find any spec's on these things. I would think there would be some difference in springs, diameter, length of the arm, etc.

In short, my question is, which unit should I buy for my mild 440 with stock points/breaker ignition?

Any guidance would be much appreciated.

 

['67Satellite]

Here's what I pulled off, Chinese I think.

 

[Mopars & Missiles]

Looks like a 20 degree vacuum advance. 10L on arm indicates how much advance the thing will provide. You double the number shown for the advance IIRC, so that one would be a 20 degree.

Also, the hex shape on the canister indicates that it is an adjustable one. Using a small allen wrench (I think it is 3/32") thru the vacuum hole, you can turn a screw to adjust the amount of vacuum (from NONE up to 20 degrees). CCW decreases advance, CW increases advance.

I had one that I didn't think worked either, but found that it was adjusted all the way CCW which eliminated any vacuum advance. Just turned it a couple turns CW and it worked fine. Just needed to fine tune it for the amount of vacuum advance that I wanted for the engine.

 

['67Satellite]

Awesome tip, i had no idea. I did suspect that there was a reason for the hex. I'll try it right now.

 

[Mopars & Missiles]

Sorry, just noticed that you said it was STOCK POINTS ignition. ops:

I don't think those are the adjustable ones, but give it a try anyway.

 

['67Satellite]

Well theres definitely a screw down there. ill play with it tomorrow more and see if i can get the advance curve to change.

 

[Secret Chimp]

On some cans, you can adjust how much advance comes in, on others, you can only adjust what vacuum level it starts coming in at. On mine the advance level is fixed but you can change how much vacuum it needs to pull everything in.