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Vacuum advance in a late 20's Buick


Dave_B
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I was talking to a guy at a car show and he was telling me about a late 20's Buick he had seen that had a 40's Chevy 6 cyl distributor with vacuum advance. I was wondering why would you want to have vacuum advance? What would the advantage be if any?

Dave

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Well, it would obviously eliminate the need to manually adjust the spark. But, nobody I know really adjusts the spark anyway, except when manually starting the car to prevent kick back. You might also get better fuel ecomony, but who really looks for that in a 20s car?

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Somewhere around 1935 Delco placed the vacuum advance on their distributors supposedly to increase gas mileage and idling characteristics for the better. It seems to have done this

at a time when their were no chips and other stuff that does it in a much better fashion.

This at cruise conditions also. Altho just how many U.S. hiways one could actually cruise

on is open to question! But I guess it did it’s purpose as we were given vacuum advance

whether or not we liked it.

The opening is somewhat critical in the placement of the opening of the unit to the

vacuum of the intake manifold. The ones that I have examined are at a place in the plate

on the carburetor at the point of where the throttle plate is at idle. Therefore I guess

that is important!

Accordingly my old Blue Motor’s Manual somewhat indicates that the Carburetors/Distributors are the same with just the Vacuum unit attached later! So if he has done this it isn’t much of a changeover, just a new Distributor and Carburetor.

It also might add better gas mileage and a better general feel to the engine.

Question; did any of the Buick sixes have vacuum advance and retard? If this is so then it just might be very easy to change them over to this setup. I’m sure they had Centrifugal Advance and Retard but not Vacuum Advance and Retard at least on the 1930!

Are there any other Engines at Chevrolet, Pontiac or Oldsmobile that had this feature? My books only go back to 1935 where Chevrolet had this feature as did Oldsmobile, Pontiac, Studebaker, and others at a somewhat later date in the 1930’s. It doesn’t sound like a difficult job for a clever person.

M.L. Anderson

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As far as I know none of the pre-war Buick 6's had vacuum advance. From what I've heard here it really does not seem like it's worth all the trouble you would have to go through to get it set up. Just my opinion..... and you know what they say about that. smile.gif

Dave

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Quote from Dave B;

As far as I know none of the pre-war Buick 6's had vacuum advance. From what I've heard here it really does not seem like it's worth all the trouble you would have to go through to get it set up. Just my opinion..... and you know what they say about that.

You still have me somewhat intrigued as some of the old Delco distributors were just modified from the old one and added the vacuum advance. My old falling apart blue Motor’s Manual has the following listings, 1935-1948 version has a bunch of distributors listed on the Straight Eights and the 1935 has a vacuum advance listed and so do the Chevrolet 6, Pontiac 6, Oldsmobile 6 starting at 1936. All of these have part number listed in the 600 series, such as 645G for 1935 Chevrolet 6, 647-A for 1935 Pontiac 6, 647-C 1937 Oldsmobile 6.

It would not surprise me one bit that one could swap parts from your old one and the upper part is interchangeable by swapping lower shafts. This still leaves the port problem.

Yours M.L. Anderson

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Quote from rlbleeker

Subject: Re: Vacuum advance in a late 20's Buick

The 1916 I just got has a vacuum advance on it. I thought that was odd for such an early car, but being new to the prewar stuff wasn't sure. I'll have to take a closer look at it.

From M.L. Anderson

I have been waiting for your answer about the Vacuum advance on your distributor, I an wondering abut it. The HOLE in the carburetor is of some significance to me.

Yours M.L. Anderson

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Here's a pic of the distributor on my '16 motor. I've no idea what it's from and I don't see an obvious part number on it. They have cut away a bit of the tin work on the starter/generator for clearance, other than that it looks like it belongs there.

post-31393-143137943702_thumb.jpg

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Re: Vacuum advance in a late 20's Buick

Here's a pic of the distributor on my '16 motor. I've no idea what it's from and I don't see an obvious part number on it. They have cut away a bit of the tin work on the starter/generator for clearance, other than that it looks like it belongs there.

This vacuum advance mechanism just cannot operate as it hasn’t a tube/pipe running from the unit to a pick-up point for the manifold vacuum. So I would have to comment that it was an add on unit. Since all the old numbers seem to be missing we will probably never know just what it is and how it got there! My guess is that it is a unit that just doesn’t belong on that engine but the only way to find out is it you can find a picture of a genuine 1916 Buick engine.

M.L. Anderson

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The reason for using the distrtibutor with the vacuum advance is that it is the distributor that the owner found that would work as a replacement for a broken original. He stated that his car was late 20's. 1926 and 1927 are late 20's cars.

Until 1928 all distributors on Buicks were made of die cast metal.

It brakes and if you can not find another one, you modify any distributor you can find that fits the hole.

1928 Distributors were cast iron and will drop right in on 1926 and 1927 cars. 1929 to 1930 single point dirstrbutors can be made to fit easily. 1931 are 8 Cyl. and will not work. The Chevy Distributors which are 6 cyl into the 50's require some machine work to use on 1926b & 27 Buicks.

1925 and earlier Buicks had the distrubutor mounted in the motor generator. I have not researched replacement distributors for those cars.

The distributor on the 1916 in the picture is not correct for 1916. Someone modified a later distributor.

The first Buick Vacuum advance was 1934 on all models.

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It is correct that the caburator must have an option for vacuum advance. If the carburator is not made for vacuum advance and you take the vacuum from the intake manifold the spark advace at idle will be too high, resulting in poor low rpm performance.

Jan

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The 1916 motor is partially disassembled, but it appears that they made no attempt to make the vacuum advance functional, supporting the theory that the original distributer was damaged beyond repair and this was the only available replacement. Given that the car was likely in South America at the time, parts were surely hard to some by.

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