17057231 or 17059232 on a 472

[Cadman-iac]

 So eventually I'm going to be using a '69 472 in a '56 Cadillac, but I'd prefer to use a newer carburetor on it with the APT.
  I have both of these carbs, 17057231, and 17059232, but they're calibrated for a 425, and both have the primary side POE system. Is that calibration acceptable for a 472, or would they need to be "tweaked" a bit, and if so, exactly where?
 I do have multiple original '69 Cadillac carbs, and if memory serves they do not use the POE system for the primary side.
 However I don't know if the specs for an early design would necessarily work on the later one due to design upgrades.
 Any thoughts on how to proceed?

 Rick

[novadude]

I don't have any good advice on how to proceed, but I believe the 7029230 Cadillac carb (1969) did have the primary POE system.  I had one of these in my "parts carb" collection, and I remember it because this is the first time I had seen one with the extra tubes.

[Cadman-iac]

I don't have any good advice on how to proceed, but I believe the 7029230 Cadillac carb (1969) did have the primary POE system.  I had one of these in my "parts carb" collection, and I remember it because this is the first time I had seen one with the extra tubes.

 Now I'll definitely need to have a look at my early carbs, I honestly don't remember any having the POE system in them.
 I've got I think either 3 or 4 sets of the POE tubes from various carbs, and I believe that they were all of the newer design, (relatively speaking),
 It's easy enough to tell since the discharge ports are highly visible in the top of the air horn.
 I'll report back once I've had a look.

 Just wanted to say that I'm not looking to use a carb specifically for the POE system, I don't know that it's necessary. I just wanted a newer model that can be easier to find in good condition, such as the two I've got now.
 I'm just not sure if the extra 47 cubic inches will require any recalibration of the 425 carbs, or if they're close enough in size and fuel requirements that they'll just be a bolt-on and go situation.

 Another reason I'm concerned is that the 305 and the 350 Chevrolet carbs are definitely calibrated differently, with only 45 cubic inches between them, so why wouldn't you need to recalibrate for the 425 to 472 swap?

 Thanks for your input, it's much appreciated.

 Rick

[Kenth]

I´d say that any of the two will work fine on the 472 as is.
Remember a larger engine will "pull" harder thru the carb than a smaller engine thus the calibration for the smaller engine often is sufficient for a larger engine.
Some testing, driving and tip-in, will reveal nessecary modifications, if any symptoms shows.

And, POE arrived 1971 for Cadillac Qjets.
1971 POE was drilled right thru the choke housing wall for exit both primary and secondary when needed.
Later on only primary POE was used.

[Cadman-iac]

I´d say that any of the two will work fine on the 472 as is.
Remember a larger engine will "pull" harder thru the carb than a smaller engine thus the calibration for the smaller engine often is sufficient for a larger engine.
Some testing, driving and tip-in, will reveal nessecary modifications, if any symptoms shows.

And, POE arrived 1971 for Cadillac Qjets.
1971 POE was drilled right thru the choke housing wall for exit both primary and secondary when needed.
Later on only primary POE was used.

  That's encouraging, I'd like to just bolt on and go if possible. And I can see what you mean about the size difference.  The 425/472's being bigger than the 305/350's, the actual difference is a smaller percentage so theoretically shouldn't require much if any recalibration. Thanks for pointing that out.

 As for the first POE system, you wouldn't happen to have a picture of how they drilled the discharge ports to work with both halves of the carb would you?  That's really interesting to me.

 I can imagine that the secondary POE probably didn't work very well with it having to clear the "shelf" of the air horn at the front of the secondaries where the hanger and rods and the air bleed tubes are located, or am I not picturing it correctly?
 It's still fascinating to see how the carburetor developed over the years.

 Thanks for your help Kenth, I appreciate your input.

  Rick

[novadude]

And, POE arrived 1971 for Cadillac Qjets.
1971 POE was drilled right thru the choke housing wall for exit both primary and secondary when needed.
Later on only primary POE was used.

It's very likely that the '69 Cadillac carb that I had was a mismatched bunch of parts if that is the case.  I will need to check the parts stash... I could also be remembering the year incorrectly.

[Cadman-iac]

It's very likely that the '69 Cadillac carb that I had was a mismatched bunch of parts if that is the case.  I will need to check the parts stash... I could also be remembering the year incorrectly.

 Novadude,

 That sounds like it's the case, I just took a quick look at my carbs, I've got 3 '69's and none have the primary POE system, neither does the '70 I've got. I have a '72, (7042237) that does have the POE system, and I see the secondary side POE system is the same as any other carb has, not what I had been thinking of earlier. The secondary POE apparently has been incorporated into the Quadrajet since 1966, as I checked every one of them for it.
 I've got a '66, '67, 3 '69's, a '70, the '72,  '74, '75, and of course the 2 '77's, and a '79 as far as Cadillac carbs go. Only a few have the primary side POE system, which makes you wonder what the requirements were that made it necessary. This '72, one of the '77's, and the 79 were fitted with it. I remember the 72 came off of a Coupe Deville, and the 77 and 79 were both removed from rear wheel drive vehicles as well, but they were all used cars when I got them, so who knows what might have been done before I bought them.
 I had never really paid much attention to how the carbs were designed and how they changed over the years before. I didn't have any source like this forum for information about it before, and until I tried using a Cadillac Quadrajet on a Chevrolet, never had another issue that I needed help with.
 This is a great forum, great people, I'm glad I found out about it.

 Rick

[Cadman-iac]

And, POE arrived 1971 for Cadillac Qjets.
1971 POE was drilled right thru the choke housing wall for exit both primary and secondary when needed.
Later on only primary POE was used.

 Kenth,

 The secondary accelerator nozzles, are these considered the same as the POE system for the secondary side of the carb, or have I confused the two?
 If so, where would the secondary POE be located exactly?

 Rick

[Kenth]

Sorry for the confusion on the 1971 and first type 1972 primary POE system, my bad.
POE should not be confused with secondary accelerator ports.

2:nd and 3:rd type 1972 Cadillac 4MV carburetors incorporate a fuel pull-over enrichment circuit to provide added enrichment and improved fuel control during higher engine speeds and caburetor flows.

Two calibrated holes, one in each primary bore, are located just ABOVE the choke valve and feed fuel from tubes that extend into the float bowl.
During high carburetor air flows, low pressure created in the air horn pulls fuel from the high speed fuel feeds, supplementing fuel flow from the primary main metering system.
The air bleeds formerly located in the air horn for the pull-over circuit, are eliminated.
The pull-over enrichment system begines to feed fuel at approximately 8 lbs of air per minute, and continues to feed at higher engine speeds to provide extra fuel necessary for good engine performance.

1971 and 1:st type 1972 models also use a fuel pull-over enrichment circuit but the two calibrated holes, one in each primary bore, and located BELOW the choke valve to provide added fuel enrichment for cold engine starting as well.
These units has air bleeds on opposite side, at the same height, of the feed holes in air horn wich was eliminated for later units. Those air bleeds were NOT ment to add fuel to the secondary port.

Note:             
                   Standard, Limousine,     El Dorado
1:st type are 7042230, 7042231 and 7042232
2:nd type are 7042233, 7042234 and 7042235
3:rd type are 7042236, 7042237 and 7042238

HTH

[novadude]

Well, as usual, Kenth is correct.  My memory was wrong on the year of my parts carb.  I finally got around to looking at it, and it is a 7041xxx, not 7029xxx as I had remembered.  It does have this system as described by Kenth above:

1971 and 1st type 1972 models also use a fuel pull-over enrichment circuit but the two calibrated holes, one in each primary bore, and located BELOW the choke valve to provide added fuel enrichment for cold engine starting as well.
These units has air bleeds on opposite side, at the same height, of the feed holes in air horn which was eliminated for later units. Those air bleeds were NOT meant to add fuel to the secondary port."

Thanks for setting me straight!!

[Cadman-iac]

Well, as usual, Kenth is correct.  My memory was wrong on the year of my parts carb.  I finally got around to looking at it, and it is a 7041xxx, not 7029xxx as I had remembered.  It does have this system as described by Kenth above:

Thanks for setting me straight!!

 So your's is a 1971 unit then? You wouldn't be willing to post a few pictures of the air horn and where the POE system comes out for both primary and secondary sides would you?
 Mine is a 1972, so only has the primary side POE.
 I'd really like to see how your's is designed if you get a chance. Thanks for checking too, I appreciate it.

 And thank you Kenth for your excellent description of these.

Rick

[novadude]

I will try and dig it out this weekend and grab some pictures of the airhorn

[novadude]

Here you go.  This is a 7041230.  You can see the POE below the Choke on the primary side, and the bleed holes that Kenth referenced on the secondary side.  The tubes from the airhorn extend directly into the float bowl.

[Cadman-iac]

Here you go.  This is a 7041230.  You can see the POE below the Choke on the primary side, and the bleed holes that Kenth referenced on the secondary side.  The tubes from the airhorn extend directly into the float bowl.

 Wow, very interesting! They hadn't finalized the design of the top of the air horn for the POE system, it's almost like an afterthought the way it protrudes from the surface. I wonder how effective it was?

 The later system doesn't have any bleeds for the POE system that I'm aware of, just the tubes that used a restriction on one end or the other depending on the year that I've noticed.
 I have either 3 or 4 sets of the tubes from various carbs, one set is just like the secondary accelerator system, open from top to bottom with no restrictions at all. I'm guessing that the restrictions were actually the discharge ports themselves, and if memory serves, these were from this '72 carb I've got.
 Then another set was installed with the restriction located at the top inside the air horn, and another set was installed with the restriction at the bottom so it was submerged in the fuel bowl. I don't know if one or the other is correct, or if both are. How can you tell? Is there any information available on these somewhere?
  Thank you for taking the time to get pictures of that Novadude, I definitely appreciate it. So cool to see how things were developed over the years.

 Rick