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vacuum advance distributor, what year did they start using this?


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I have a 1934(very late 34)  engine in my 1932 56S.


It has a single point vacuum advance distributor on it, post-154773-0-92042600-1449627770_thumb.post-154773-0-48851400-1449627809_thumb.


I was wondering what year Buick started using this kind of distributor, I know it was after 1932.


Also can you give me advice to test and see if it is working properly( the advance part)?


Thanks for your help! 

Edited by bmg1959 (see edit history)
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1934 was the first vacuum advance on Buicks.  The 1932 1933 cars had mechanical advance only.  I believe in 1934 there were 3 advance mechanisms,  dash Octane selector, mechanical flyweights and vacuum advance.  Early cars had the mechanical advance on the dash, and then mechanical flyweights.


My Motors Manual tune up chart for 1934 states "With octane selector advanced fully, breaker points open when the ADV 7 mark on the flywheel aligns withe the peep hole pointer."  The vacuum advance should add  12 degrees for a total of 17 degrees advance.  No rpm is stated for the vacuum advance setting.


As a simple test for operation, put a chalk mark on the crank pulley when the flywheel ADV 7 is aligned in the peep hole.  Then hook up a timing light to # 1 plug wire, start the engine and you should be able to see the mark advance as you increase engine rpms.


I still prefer to pull the distributors and take them to a shop with a Sun distributor machine.  This way everything can be tested and set to the proper point gap, flyweight advance curve and a check on the vacuum advance.


Bob Engle

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  • 3 weeks later...
bmg1959, sorry if this TMI (too much information!):


Let me expand on what Bob said above.  First, your distributor has two distinct advance mechanisms:


1) The first type is a  Mechanical Advance system, of which there are two common sub-types. The first sub-type of mechanical advance is the “manual” style consisting of a lever or cable on the dash or steering wheel. When manually pushed/pulled, the cable/lever advances or retards timing.  If there is no mechanical dash to distributor linkage, then the distributor employs an “automatic” or centrifugal mechanical advance system (using weights and springs under the breaker plate). 


2)  The second type of distributor advance is the Vacuum Advance system.  The vacuum canister hanging on the side of the distributor is a give-away for a vacuum advance system.


Do you have a dash “octane selector”? I don’t see any linkage in your photos.  Bob’s advice on testing the advance would apply if you have a dash selector type of mechanical advance.  If your distributor has weights (also known as a centrifugal advance), there is a little more to the story.


Just to clarify, since I don’t see any mechanical dash to distributor linkage in the pictures, I will assume that you have a centrifugal mechanical advance.


If you are inquiring about how to tell if the VACUUM ADVANCE is working on your distributor, you need to check it independently of the MECHANICAL (centrifugal) ADVANCE.  One way to do this is to disconnect the steel vacuum line going to your distributor. Plug the line with a rubber vacuum cap.  Now you are testing MECHANICAL (centrifugal) ADVANCE only.  


Follow Bob’s advice with the timing light to see that the chalk line moves with engine rpm. Note the chalk mark position at idle.  Now slowly increase rpm watching for the chalk mark to move. At some rpm, the chalk mark will stop moving (maxing out, for instance, @ 7 degrees advanced, if that is what the manual calls for).  At that point, the mechanical advance has reached its limit.  Now, lower the rpm back to idle and watch for the chalk mark to return to its original position.


By the way, if you had one, you can test a manual (dash-lever) mechanical advance system in the same fashion. Simply move the dash lever and watch the chalk mark move up and down.


Now, on to testing if the VACUUM advance is actually working.  For this test, you will need a hand-held vacuum pump (available at any parts store for $29.00).  Using a length of vacuum hose, connect the distributor vacuum can to the pump. Don’t touch the accelerator. Start pumping the vacuum pump. You should check to see if the chalk mark starts to move as the vacuum level is slowly increased. 


If Bob is correct about the 12 degrees vacuum advance specification, you should see the chalk mark advance about 12 degrees and then stop moving at a certain vacuum level.


Also, the vacuum can should be able to maintain that level of vacuum for some extended period of time, (i.e., that the can doesn’t leak.)  This now is only checking basic functions; Does the advance system(s) work or not?


The actual advance curve is specified in factory manuals.  On my Sun machine, I would actually graph a series of data points (the vacuum advance curve) indicating how many degrees of vacuum advance occurs at what vacuum level. One can match the factory curve, or “re-curve” it to accomplish various performance changes. Likewise, the Sun machine can plot the mechanical advance curve. Here I would plot engine rpm vs. distributor advance in degrees.


To learn more about what the two types of advance systems do and what effects each one has on engine performance, you will find plenty of forum discussions on those topics.


Nice Buick, by the way! 

Merry Christmas, Joe

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I have the dash knob advance system. 

I think my distributor is working pretty good, had the car out running good on Thursday.

What is weird is I found out I need to pull my chock on about 1/4 of the way or the car will not accelerate hardly at all,

But when I add the chock it runs really good. I just rebuilt the carb too.

I had it up to 60 MPH and she was humming nice!

So I think all the advance stuff is working good or it probably would not have ran that good.

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