1957 Dual Carb Distributor info needed

[Dan S]

Hello. I am putting together a 1957 with the dual carb option and noticed there are two part numbers for the distributors. I believe it's 1110876 for single carb engine and 1110877 for dual carb engine. The problem is that I have 2 single carb distributors. I have been doing a lot of searching and cannot find what the difference is between the two part numbers. I assume it's just the advance curve but can anyone confirm? I have also found different part numbers for the vacuum advance, so can I just find a vacuum advance for the dual carb distributor? Thank you for any help.

[TJ Hopland]

I don't have any experience with the Cadillac but I do remember reading that with some other multi carb setups the difference is physical for clearance.   One may be taller or shorter to clear something or in the cases where the distributor goes through the intake maybe the height of the multi carb intake vs the block is different.

I'm sure someone here will know for sure but maybe my guess will give you a direction to explore while you are waiting for the real answer.

["Cadillac Kid" Greg Surfas 15364]

Dan,
If you are not looking for a "numbers perfect" car, you can have your single carb distributor re tuned to match the advance curve of the dual carb unit.  I don't know and it goes under the numbers perfect heading but didn't some of the multi carb motors use dual points.  Again, for operation a single point distributor will function adequately.
Greg Surfas

[Dan S]

I think my issue is going to be finding a correct distributor regardless of what I want. Do you know if both the mechanical and vacuum advance are different? Or can I find a dual carb vacuum advance and put it on? I haven't come across anything that would indicate it was dual points but it seems the info is lacking in regards to this particular distributor.

["Cadillac Kid" Greg Surfas 15364]

Dan
I believe this is what you want if you want the correct one.
http://www.cadillacpartsltd.com/19caelducadi.html?viewfullsite=1
Otherwise going back into the AC Delco catalogs will tell you the differences between this nd the single carb distributor.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

Dan I am surprised that someone with direct knowledge of the 57-2x4 set up, but now I know why I keep billion year old parts catalogs.  It appears that both those distributors have the same mechanical advance and vacuum advance curves. Any difference must be in the physical distributor.  Most likely in the location of the point adjustment window. Or
Greg Surfas

[Roger Zimmermann]

I have two cars with the dual carb set-up, a '56 Biarritz and a '57 Brougham. Some years ago, I sold my '56 SdV. I never noticed a difference in the distributor from all 3 cars, but I did not check if my Brougham has the right one. Sorry, it's a mystery for me!

[chrisntam]

The time to buy a rare part is when you find it.  Thanks to Greg for finding it. 

[J. Gomez]

Dan,

FYI

The MPL from January 1959 shows the vacuum advance has a different part # between the single and dual carbs, the other distributor components that are listed do show the same parts for either model.

Not sure if a different advance would dictates a change on the distributor part # or not.    There are a few items having a N.L. part # but I doubt these would have any impact on the function between the single and dual carbs.   

HTH

[fishnjim]

Glad you found one.   
FYI - All depends what you want/are after; "authentic", max. performance, functional.   
You can run the stock dist even w/o advance and it'll function, just not max power, but probably more than you'll need.   Unless you're a 50s carb guru, you'll probably have a chore tuning that set-up anyway.  (beware what you ask for, you might get it)

There's many cars running poorly or out of time everyday.   When we dyno'ed the 365, I converted to 3x2, it ran to 300 hp /5000 rpm with no advance.  Yeah it was pretty flat after 4200 or so.   It's got a stock dist/advance.   They made a special cap for these, very expensive now, and really wasn't necessary, aka clock the dist.   I put pertronix on it, so I wouldn't have to fuss with the points also.   There's solutions for everything.   Take a point off, it's not "authentic", newer SBC carbs, electric choke.  Who cares?   It'll be running for another 60 years.
Better up your fuel budget, if you step on it...Makes sure the brakes are 110%.

This is a strip set-up and not sure what Cad was thinking in the day, wow factor?   I suspect the competitor Chrysler/DeSoto cross ram hemi's may have had something to do with this offering.  Or racing parts.   '57 was a weird car year in a lot of ways.     

[Dan S]

Thanks everyone for all the responses and info. I have a shop manual but no parts catalog, so this info is helpful. I did see that NOS distributor but wasn't sure yet if it would even be worth the money if it was not physically different, and I could just exchange parts out with my other distributor. Comparing my single carb distributor with the picture of the NOS one, they look identical in orientation. I will probably just use my good condition single carb distributor, as I already have a nice delco stamped vacuum advance as well. This car will not get many miles at all, and will not see higher rpm operation more than a few times I'm sure.

That being concluded, can I piggyback off this post and ask for a very high quality carburetor restoration source? I need these dual carbs gone through and re-plated to factory specs, as well as a Carter from another non-Cadillac that needs done. I have used a few places in the past and not been satisfied with the quality.

["Cadillac Kid" Greg Surfas 15364]

Dan,
There is apparently SOME physical difference between the two.  If you can, do a "mock up" of the the intake/carbs/distributor and see if there is any interference with your distributor.  If no I personally would not hesitate to go with the single carb dist/vacuum adv.
Greg Surfas

[Dan S]

Thanks Greg. I'll keep you updated if I find anything.

[J. Gomez]

Dan,
There is apparently SOME physical difference between the two.
Greg Surfas

It may well be the differences could be the internal parts that are listed as N.L. on the MPL, maybe the weights since the vacuum advance is listed different for the dual carbs.      

["Cadillac Kid" Greg Surfas 15364]

Jose,
Since the vacuum advance specs are the same I would (with no actual knowledge in this particular case) guess that perhaps the vacuum fitting or location on the component might be the difference.
Greg Surfas

[Mike Baillargeon #15848]

My 57 Eldorado has been gone for a long time but if my memory is correct it was a physical difference between the 2 distributors.

It had to do with the way you adjusted the points or the timing....the cap couldn't be turned without hitting the rear 4 barrel...or the points couldn't be adjusted because the rear carb was in the way....if you had the single 4 barrel distributor....

I remember the distributor cap was different...in that the point adjusting door was in a different place between the single & dual carb cars....

Mike

[J. Gomez]

Jose,
Since the vacuum advance specs are the same I would (with no actual knowledge in this particular case) guess that perhaps the vacuum fitting or location on the component might be the difference.
Greg Surfas

Greg,

I found the following specs for both type of vacuum advance as you can see they do show different specs for both. The 1111624 used on the dual carbs shows opening at a lower ”Hg than the 1116122 used on single carbs.

I’m not sure if the differences between them would have an impact on the timing at any RPMs on the dual carbs engine, you may know more on that subject than I.   

I know for the ’56 “sellers” advertise the vacuum advance to fit the ’56, it does cosmetically BUT operational it does not.    The ’56 has the 1116103 which opens at 17 while the replacement opens at 11. That is why if you find a NOS it will cost both arms and legs.     

["Cadillac Kid" Greg Surfas 15364]

Jose,
It looks like (from this page) that the early vacuum advances had a different curve, but the later ones are so close I don't think it is outside the range of tolerances between the later one and the standard.  Just my observation.
Greg Surfas

[Dan S]

Just some info I found to contribute to this discussion:

From the 57-58 cadillac lasalle club authenticity manual, second edition, page III-7: "The same basic distributor was used on all cars of the period. The GM part number varies due to the fact that the centrifugal and vacuum advance characteristics differ with different carburetors and from year to year...On three-carburetor "Q" engines in 1958, a slight modification of the distributor cap should be evident to make the distributor point dwell adjustment easier to accomplish...On "Q" engines, the adjustment window should be adjacent to one of the cap hold down screws, on regular engines, it should be midway between two hold down screws." It mentions the "Q" engines but does not specifically say 1957, the wording makes it seem like its talking about 1958 "Q" engines. Either way I believe based on this, the centrifugal and vacuum advance are different for the dual quad engine.

It also states that eldorado engines (EDIT: 1958 Eldorado engine) had base timing of 10* advance instead of 5*, so the harmonic balancers were different as well with and extra mark at 10* advanced.