vacuum advance cans interchange between distributors?

Posted By: patrick

vacuum advance cans interchange between distributors? - 08/31/09 11:49 AM

in tuning my new engine combo, I found that the vacuum advance can is DOA on my dizzy. I was wondering if they are interchangeable between the factory electronic ignition dizzy's (what I have) and the older points style? I'm thinking an older app might have a can with a little less total advance built in (I'd like one with ~14-15 degrees, my dead one has 17 degress, most I've found are ~22), which would suit my combo better.

also, does anyone know if the aftermarket ones from Standard or Airtex are adjustible like the factory ones?

thanks in advance

Posted By: JohnRR

Re: vacuum advance cams interchange between distributors? - 08/31/09 01:25 PM

Yes the electronic one will fit a points and vice versa , I turned a new electronic unit i had into a points unit , just swapped the breaker plate and the points cam , the factory is adjustable so i'm a bit confused on your total amounts quoted . , never checked the aftermarket units to see if they are adjustable but I would assume they are ???

Posted By: RapidRobert

Re: vacuum advance cams interchange between distributors? - 08/31/09 01:49 PM

iirc the cans wont interchange as the angle of the arm is different between the two but it has been decades since I was mixing/matching parts on that deal. You could (even JB

) weld something on both sides of the stop so it cant be pulled in as far like 2 little snips of wire of the right thickness. As double R said I'd be surprised if the aftermarket ones weren't adjustable also.

Posted By: patrick

Re: vacuum advance cams interchange between distributors? - 08/31/09 04:05 PM

Quote:

Yes the electronic one will fit a points and vice versa , I turned a new electronic unit i had into a points unit , just swapped the breaker plate and the points cam , the factory is adjustable so i'm a bit confused on your total amounts quoted . , never checked the aftermarket units to see if they are adjustable but I would assume they are ???

the adjustment on the cans are only for preload--when the vac advance begins advancing. the length of the slot on the arm determines the total advance.

Posted By: hooziewhatsit

Re: vacuum advance cams interchange between distributors? - 08/31/09 04:38 PM

When I got my truck, I found my vac advance can was seized up as well.

I found two different kinds in the junkyard. From the top the arm on one hooked left and back (mine), and the other hooked right and back. They were enough off from each other you'd have to do a lot of customizing to make the wrong one work.

Weirdly, the one I got in the junkyard does not have a stamp on it saying how much advance it provides.

Posted By: JohnRR

Re: vacuum advance cams interchange between distributors? - 08/31/09 05:24 PM

Quote:

Quote:

Yes the electronic one will fit a points and vice versa , I turned a new electronic unit i had into a points unit , just swapped the breaker plate and the points cam , the factory is adjustable so i'm a bit confused on your total amounts quoted . , never checked the aftermarket units to see if they are adjustable but I would assume they are ???

the adjustment on the cans are only for preload--when the vac advance begins advancing. the length of the slot on the arm determines the total advance.

I didn't know that , I assumed that adjusting the spring pressure changed the amount it advanced ? Good thing I run them disconnected I guess

Posted By: Crizila

Re: vacuum advance cams interchange between distributors? - 08/31/09 09:06 PM

Quote:

Quote:

Quote:

Yes the electronic one will fit a points and vice versa , I turned a new electronic unit i had into a points unit , just swapped the breaker plate and the points cam , the factory is adjustable so i'm a bit confused on your total amounts quoted . , never checked the aftermarket units to see if they are adjustable but I would assume they are ???

the adjustment on the cans are only for preload--when the vac advance begins advancing. the length of the slot on the arm determines the total advance.

I didn't know that , I assumed that adjusting the spring pressure changed the amount it advanced ? Good thing I run them disconnected I guess

Vacuum advance units are great mileage improvers and will help your modified engine run better -( idle and cruise imparticular ). If you are doing an all out race car, chuckem. On the street or dual purpose, useem - IMO.

Posted By: Dartcuda

Re: vacuum advance cans interchange between distributors? - 09/01/09 01:48 AM

NAPA sells vacuum advance units with different degrees of actuation to fit mopar distributers , just look them up in one of their paper catalogs. I have found that the 8.5 (17 degrees) works best , gives 52 degrees total with 35 degrees of mechanical. They are adjustable.

Posted By: patrick

Re: vacuum advance cans interchange between distributor - 09/01/09 02:00 AM

I think that's what I'm going to go for....was spending some time on rockauto, and it looks like airtex #4V1084 or Standard Motor Products VC184 is the 8.5 one (which is what was on my dizzy that went bad) was wondering if there was a 7.5 one out there (15 degrees advance)

Posted By: JohnRR

Re: vacuum advance cams interchange between distributors? - 09/01/09 12:15 PM

Quote:

Quote:

Quote:

Quote:

Yes the electronic one will fit a points and vice versa , I turned a new electronic unit i had into a points unit , just swapped the breaker plate and the points cam , the factory is adjustable so i'm a bit confused on your total amounts quoted . , never checked the aftermarket units to see if they are adjustable but I would assume they are ???

the adjustment on the cans are only for preload--when the vac advance begins advancing. the length of the slot on the arm determines the total advance.

I didn't know that , I assumed that adjusting the spring pressure changed the amount it advanced ? Good thing I run them disconnected I guess

Vacuum advance units are great mileage improvers and will help your modified engine run better -( idle and cruise imparticular ). If you are doing an all out race car, chuckem. On the street or dual purpose, useem - IMO.

I knew someone would take the bait ...

Posted By: patrick

Re: vacuum advance cams interchange between distributors? - 09/09/09 02:29 PM

update-

picked up a Standard Motor Products VC184, it's app is for an '88 dodge 1 ton 360. has 17 degrees advance (most others are 22), and is adjustable for the tip-in point, like OEM.

2 days later and $23 shipped to my door from rockauto. all the local parts stores wanted about $40 and 7-10 days for them.