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1956 Vacum advance

Started by okccadman, September 12, 2010, 04:21:50 PM

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okccadman

Can anyone tell me what years interchange on the distributor vacum advance for an air conditioned 1956 Series 62?

Thanks in advance,

Jim
Jim Jordan CLC# 5374
Oklahoma City, OK

55 Series 62 Sedan
56 Series 62 Coupe
56 Fleetwood 75 Derham Limo
59 Fleetwood Sixty Special
66 Fleetwood Brougham
66 Superior Hearse/Ambulance
67 Fleetwood Sixty Special
68 Fleetwood Eldorado
76 Coupe de Ville d'Elegance
90 Brougham
92 Fleetwood Coupe
93 Allante
94 Fleetwood Brougham
02 Eldorado Commemorative Edition

Warren Rauch

 1956 was a one year vacuum advance( #111 6103), but it fit air and non air cars. In 1956 they did less of the advance with the centrifugal advance ( only 10 degrees vs 12 for 1957) and more on the vacuum ( 18 vs 12) I used a 1957 advance on my 56 for a short time , it ran OK for me up to 55mph. Warren

okccadman

Anyone know if the 56 unit is available new anywhere?
Jim Jordan CLC# 5374
Oklahoma City, OK

55 Series 62 Sedan
56 Series 62 Coupe
56 Fleetwood 75 Derham Limo
59 Fleetwood Sixty Special
66 Fleetwood Brougham
66 Superior Hearse/Ambulance
67 Fleetwood Sixty Special
68 Fleetwood Eldorado
76 Coupe de Ville d'Elegance
90 Brougham
92 Fleetwood Coupe
93 Allante
94 Fleetwood Brougham
02 Eldorado Commemorative Edition

Otto Skorzeny

Standard made them but it's been discontinued. Somewhere I have the Standard part number.

The replacements sold by USA Parts and represented to be for 1956 are in fact not correct. They do not advance as far as they are supposed to at idle.

Your best bet is to have your original rebuilt.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

okccadman

Otto, does your vendor list tell who offers rebuilds on these or is it a simple process?
Jim Jordan CLC# 5374
Oklahoma City, OK

55 Series 62 Sedan
56 Series 62 Coupe
56 Fleetwood 75 Derham Limo
59 Fleetwood Sixty Special
66 Fleetwood Brougham
66 Superior Hearse/Ambulance
67 Fleetwood Sixty Special
68 Fleetwood Eldorado
76 Coupe de Ville d'Elegance
90 Brougham
92 Fleetwood Coupe
93 Allante
94 Fleetwood Brougham
02 Eldorado Commemorative Edition

J. Gomez

Jim,

You have a PM with more details on this topic..!

J. Gomez
CLC #23082

Otto Skorzeny

Hey Jose, PM me too. Inquiring minds want to know.  ;)
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

J. Gomez

J. Gomez
CLC #23082

Caddy Wizard

Here is the straight skinny on the vacuum advance....


My vacuum advance unit was completely shot -- no advance and the thing was a pure vacuum leak.  Fortunately, the vacuum unit on the modern-style '56 distributor is the same basic design that GM used for decades to follow. So while the exact fit unit is no longer available (spring rate and screw connection to vacuum), I was able to take my original apart and use the guts from a common later unit (that I also took apart). The diaphragm and its attached rod are EXACTLY the same as my original. The Echlin unit I got from NAPA for this purpose is VC1765. Cost about $10 -- works perfectly. My old unit is now absolutely as good as new.   The following is how I did it.

 

To do this, I clamped the old unit in a wooden vise, using a pair of wooden blocks to grip the stem of the housing.  I cut a V-groove in one of the blocks to receive the movable shaft (the actuator rod).  With the unit securely clamped in the vise, I carefully prised open the "can" using a small custom-made chisel.  I took a narrow pin punch and sharpened the end into a skew chisel and bent its shaft to work around the curvature of the canister a little bit.  Using this very narrow skew chisel, I started to work my way around the bent-over lip of the canister.  Once I had a little length of it prised up just a tad from the cover, I took pliers and bent it up straight, a little at a time, working my way around the cover.  Be careful, as at a certain point the cover will come loose and the spring will pop it up in the air.  Then it was a matter of cleaning the inside and discarding the old diaphragm/rod assembly.  I followed the same procedure to harvest the diaphragm/rod assembly from the new VC1765 and installed it in the old canister.  Then I buttoned it up by gently folding over the edge of the canister over the cover by gently tapping it with a very small hammer, again working a little at a time.  In the end, it looks just about perfect and works as good as new.
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Otto Skorzeny

As I understand it, you re-used the spring from the original? The spring is the main part which controls the amount of advance, right?
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

Caddy Wizard

Yes, you should re-use the spring (it doesn't really wear out).  The spring is the main difference in the various years, along with the outside stuff like how the vacuum line connects.  The part that wears out is the diaphragm.  You can buy neoprene sheet if you want, but taking apart the diaphragm assembly and reconnecting it after you replace the neoprene is difficult -- I know, I've done it on 1949 units.  On the '56 unit, the Echlin part I referenced has the EXACT fit diaphragm and rod assembly.  It is just a matter of carefully opening the can to replace it and then carefully closing it back up.  It is tedious to do it without making a mess of the thing, but if you are careful it can be done.


And there is no sense is buying a NOS unit other than for show only.  A 50 year old NOS unit will fail shortly after you start to use it -- the 50 year old rubber diaphragm will tear apart once the vacuum and the spring start sawing it back and forth.  No, it is better to rebuild the old one than to buy a new one. 


Art
Art Gardner


1955 S60 Fleetwood sedan (now under resto -- has been in paint shop since June 2022!)
1955 S62 Coupe (future show car? 2/3 done)
1958 Eldo Seville (2/3 done)

Jay S. Friedman

I think that besides the spring, another determinant of the advance rate of the mechanism is the length of the "rod"; that is, the thin, flat part that goes into the distributor, connects to the breaker plate and thus determines its position. 

Glen

#12
What precisely is it that prevents the unit from advancing as far as needed?  The reason I ask is because I had a problem with the vacuum advance units I got for the parts stores.  They advanced too far.  They were correct as far as vacuum vs. advance, but at full manifold vacuum it would go to 22 degrees, way beyond the max 12 degrees my engine wanted.  

After studying it a bit I added a small piece of metal to prevent it from going too far.  Now the engine runs cooler and does not ping at light throttle.  

So I was wondering if it was possible to get a more common advance unit and modify it to allow it to advance the extra amount to make it work.  

Just a thought.  

Glen  
Glen Houlton CLC #727 
CLCMRC benefactor #104

CEC #20099

CEC #20099 Vac Advance;
The metal shaft coming out of the unit to the breaker plate usually has a 2 sided slot that controls the range of motion ( degrees of advance). By filling in the slot with a stop or welding, you will limit the total advance. If you need more, file the slot longer. The put the distributor on a SUN Distributor machine and check out Centrif & Vac advances. Just because you got a part to fit, does not mean it is working correctly. The octane of the fuel you are using may affect the amount of vac adv you want. CEC.

Bob Steur

Just a tip - Accel and others make adjustable vacuum advances. As a bonus they look like the originals with a hex shaped can.

http://www.summitracing.com/parts/ACC-31034/


Glen

Maybe I don’t know where to look, but I’ve never found an adjustable vacuum advance for a car older than 1970. 

The units I get at the parts store is OK as far as vacuum to advance up to 12 degrees of advance.  They go beyond all the way to 22 degrees which is right for the newer engines but is wrong for the ’68. 

The only difference between them is the new ones are allowed to move a greater distance.  So it makes sense to just put a stopper on the new ones. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

CEC #20099

CEC #20099
Old time Mopar & Ford guys know how to adjust the vacuum advance RATE. Slide an allen wrench in the vacuum nipple & see if there is a hidden calibration screw. Do this by feel, for the hex may initially be stiff. Typically the screw changes the spring tension. Aftermarket units for GM may have this feature. It has been a long time since I was doing this on a 77 Chev 305. I doubt if factory GM units have this.

c.chleboun