[Old Goat Racer]

I have a carter AFB 4242S M6 PD
Can anybody tell what it came off of ?
Thanks, OGR

[tom s]

1967 400 A/T none CA carb.Tom

[GT182]

I'd say a 66. Quadrajets started in 67. Not sure if Quads came out at the beginning of 67 production or not, so Tom could be correct. But I've never seen an AFB on a 67 400.

Not listed here for 67..... http://www.carburetion.com/Number/oembymodel.asp Add year and GTO then search.

Tom.. non CA.

[tom s]

All big cars in 67 got AFBs,B bodies and F got QJs.Tom

[Old Goat Racer]

Tom is right. I've personally seen one. My MPC agrees.
Also my 1977 MPC says 1966 421 H.T. -4 B.C.

[John V.]

Tom is correct except I think he meant to say '67 A bodies and F Bodies got the Q-Jet.

And to further clarify, the '67 A body & F body got the Q-Jet for the 400, the 4 bbl 326 continued to use the AFB (but not the 4242S).

The specific '67 big Pontiac auto trans engine codes that I show for the 4242S are:

XC (I believe this was a low comp export engine with 142 head, 293 HP)
YE (early year with the closed chamber 143 head, 325 HP)
XW (late year with the open chamber 061 head, 325 HP)
YF (early year with the closed chamber 143 head and A/C, 325 HP)
XX (late year with the open chamber 061 head and A/C, 325 HP)
XH (GP engine, 670 head, 350 HP)
XJ (GP engine, 670 head and A/C, 350 HP)

References may also show this carb for the '67 WF code engine and list it as an auto trans engine code.

I believe that is an error, I believe this was a GP man trans engine code and would have used a 4243S AFB, 670 head and A/C, 350 HP.

W* coded engines were invariably man trans engine codes, I don't think the '67 WF was any exception.

No '66 engine would have gotten the 4242S as O.E. AFAIK. The '66 auto trans 421 was specified with the 4037S AFB.

[tom s]

Yes,hate body codes!I just went to Jons site and found it.I believe CA cars got a diff number,will go back and check.Tom

[tom s]

yes,CA cars got diff carb numbers for both A/T and man.Tom

[Jeff Hamlin]

There are a few black and white factory/promo engine images that show a '66 Sprint engine with an AFB 4BC and CA smog style breather but I've never seen a production mounted AFB.

I guess they really wanted to get more oohs and aahs with the introduction of the NEW Sprint 6 sporting a Q-Jet...

[GT182]

Thanks for that John. I figured that's what OGR meant but wasn't all that sure. That was the only reason I jumped in. Great info all the way around, and great photos too.

[carbking]

Jeff - after you made your post about the Sprint, I checked the Carter records. Carter never issued an AFB carburetor for the Sprint 6 cylinder, even an experimental one. Pontiac probably mocked up an engine with an existing production carburetor. I would love to see the B & W you mentioned. Would be interesting to try to determine which AFB was used.

Jon.

[John V.]

Jeff, I was going to mention this bit of trivia that the '66 4 bbl OHC6 was the first Pontiac engine to get the Q-Jet but left it out of my post.

Thanks for sharing.

I also was not aware of the pix you mention.

The '66 MPC I have lists the Q-Jet for the 4 bbl OHC6, one for the man trans, one for the auto trans. No other application distinctions and no indication of any AFB usage for this application.

Jon, do you suppose PMD went to the Q-Jet for the Sprint 6 to meet '66 Cal emission requirements whereas the AFB might have required more elaborate controls?

Just as interesting would be the intake. Seems to me PMD engineering would have had to have produced a specific intake for the OHC6 AFB install, correct? And may have been far enough along with it to have given it a full-fledged p/n that eventually was not needed for production.

Any idea how early the Q-Jet was introduced by Rochester? Or any other thought why PMD chose it over the AFB for the '66 OHC?

[Old Goat Racer]

Originally Posted by John V.

No '66 engine would have gotten the 4242S as O.E. AFAIK. The '66 auto trans 421 was specified with the 4037S AFB.

O.E. is the catch. Neither my 1966 or my 1970 MPC says it used the 4242S BUT
my 1977 MPC says it does. No doubt it was "the replacement carb" sometime after 1970 ? Any thoughts ?

[Jeff Hamlin]

Originally Posted by carbking

Jeff - after you made your post about the Sprint, I checked the Carter records. Carter never issued an AFB carburetor for the Sprint 6 cylinder, even an experimental one. Pontiac probably mocked up an engine with an existing production carburetor. I would love to see the B & W you mentioned. Would be interesting to try to determine which AFB was used.

Jon.

I have no doubt it was a one off and/or mock engine put together before 1966.
IRCC the OHC program was started in late 1963 so who knows what they may have had worked up.
I couldn't locate the photograph which is likely lost with the 1000+ other files from my PC crash earlier this year.
I was able to pull the same image from a 1965 Popular Science. No mention of this within the article so again likely a file photo from Pontiac?


Sorry for the highjack.

[John V.]

O.G.R., the '66 MPC only indicates the PMD issued p/n for the Carter Carbs for the '66 applications, does not additionally note the Carter Model No., unlike the past Model Year applications which reflect both the PMD issued p/n and the Carter Model No. But I have other references to identify the O.E. carbs by engine code and Carter Model No.

I'm certain the '77 MPC listing for the '66 4 bbl 421 with auto trans indicating the 4242S is either an error or more likely, just a normal consolidation of Service Part usage as certain O.E. p/ns were superseded, obsoleted, and eliminated. This happened all the time which is why one has to take great care trying to establish O.E. p/n usage from the MPC Service Part listings. Oftentimes, the O.E. p/n was immediately superseded by the following Model Year p/n. The Service Part p/n listing would lead you to believe the following year p/n was the O.E. production p/n when it was not. I find this for my '64 GTO, the '66 MPC lists the '65 p/ns for Muncie 4 spds and the chassis frames but the '65 p/ns were not the original equipment for a '64 build so I have to look deeper to learn the original '64 p/ns used in production. The superseding p/ns usually will fit and more or less function same as the O.E. p/n part it is replacing but it is not correct O.E. if "numbers matching" is the criteria.

The main reason I'm certain the 4242S was not used on any '66 engine in production as O.E. is due to how Carter issued their Model Nos.

Jon can correct me if I'm wrong and there is the slim chance that the 4242S entered production late in the '66 Model Year as a substitute for the original carb specified for the '66 4 bbl 421 with auto trans which was PMD p/n 9783189 and Carter Model No. 4037S for both the YH and YZ code engines.

The key is that Carter Model Nos. for PMD usage were established in a way that either on purpose or by happenstance makes the Model Year of application pretty obvious in most cases. There is an obvious pattern to the Model Nos.

This is what I have found going back to '58, I have omitted the various SD applications as I know little about them and they don't quite fit the numbering pattern:

'58 Carter Model Nos. are 27**S
'59 Carter Model Nos. are 28**S
'60 Carter Model Nos. are 29**S
'61 Carter Model Nos. are 31**S
'62 Carter Model Nos. are 33**S (some usage of carried over 31**S occurred in '62, not sure why)
'63 Carter Model Nos. are 34**S (several applications however used 33**SA, not sure if these were leftover '62 carbs reworked with an "A" added to the Model Nos. or if there is some other explanation. Also, some 421HO applications were equipped with a 3545S and the 326HO with auto trans was equipped with a 3502S)
'64 Carter Model Nos. are 36**S
'65 Carter Model Nos. are 38**S, the 326HO with auto trans was equipped with a 3900S
'66 Carter Model Nos. are 40**S
'67 Carter Model Nos. are 42**S

The last 2 listings explain why I said the 4242S would not have been used on any '66 engine. It is my belief that Carter would not have produced this Carb Model No. until just before the '67 Model Year production began and PMD would not have installed it on any engine until '67 Model Year final assembly production began.

But I'm also guessing that a 4242S could be used for all sorts of applications if originality is not a concern. The proliferation of Carter Model Nos. during a production run rather than a "one size fits all" approach is due to the fact that production volume allowed PMD to specify carbs with particular performance specs for each individual engine combo and Carter would produce it to suit with a unique Model No. For Service Replacement, as volumes declined to near zero, likely you were given far fewer carb spec choices. If a 4037S was ever so slightly different from a 4242S, the 4037S could be eliminated and the 4242S given a broader range of application coverage.

[Old Goat Racer]

I agree and totally understand. Working 30 years at a GMPD I saw it all the time. We called it a "PCN". Didn't the 66 GTO head # 093 replace the 65 GTO head # 77 ?
And I do know 1st hand that this carb was sold over the counter, just can't remember what year.
The only info I have is my 3 MPC's. Which I know we can't always trust.
Thanks for your expertise. I know who to ask next time.
OGR

[carbking]

John V - see my listing of all AFB's designed for Pontiac in the "Street" forum. Carter did assign number in ascending numerical order (Carter number 1 was an experimental carb for a 1923 Chevrolet). The numbers did not suggest a year such as Rochester numbers, only the next sequential number. Fuel pumps were also numbered in the same numbering set, so some "missing" carburetor numbers are actually fuel pumps. The "M6" from the OP's original post tells us his carburetor was produced in December 1966 for a 1967 model car. Also, you referred to the "A" often appended to the "S" with the Carter number. From our website:

"Carter numbering systems. Three different types of numbering systems are found on Carter produced carburetors.

(1) On carburetors built for Chrysler Corporation, a series of 3, 4, or 5 letters and numbers; i.e. EV1 or D6H2.

(2) On carburetors built for Ford Motor Company, the “Ford” numbering system which is “lnll – l(l)(l)” or letter, number, letter, letter dash letter (possible letter) (possible letter) i.e C5VF-A. This system is codified in that the first letter is the decade (B=1950’s, C=1960’s, etc.); the number is the last digit in the year; the 3rd and 4th letters (before the dash) represent the vehicle model (VF=Lincoln); and the letter or letters after the dash are a modifier which distinguishes the exact application. Thus in the example C5VF-A, the carburetor would have been the first application for Lincoln in the year 1965.

(3) The traditional Carter numbering system which consisted of 1, 2, 3, or 4 digits; followed by the letter “S”, possibly followed by another letter. It is extremely doubtful that any of the single, double, or early triple digit tags will appear; as they were produced before 1930 and were constructed of red cardboard. The metal tag appeared about 1930 with tag numbers of about 300s. The 4 digit tag appeared in 1952, and was continued on until the end. The letter S and following letters, when present, have caused much speculation (mostly incorrect). In Carter’s terminology, an individual part such as an idle mixture screw was a single part; whereas two or more individual parts sold together such as a needle, seat, and gasket were sold as an “assembly”. Carter used the suffix letter S to denote assembly. Since all carburetors are composed of multiple parts, the letter S was appended to all carburetors using the traditional numbering system i.e. 938s. If a significant engineering change was made to the carburetor, the letter “A” would be appended to the S (i.e. 938sa). A second change would have the letter A replaced by the letter B (i.e. 938sb). The highest engineering change of which I am aware is 4, i.e.938sd. Contrary to popular belief, the S DID NOT mean standard transmission, nor the SA automatic transmission."


Jeff - thanks for the picture. VERY interesting. Pontiac never had an AFB with a choke pull-off!!! Difficult to tell with a front picture alone, but GUESSING this is either a 4027s or 4028s Carter AVS from a 1966 Chevrolet 327! It could also be a small Chrysler carb, but Pontiac would be more apt to have the Chevrolet carb in house than the Chrysler. AND, the eventual Q-Jet used on the Sprint was basically a 327 Chevrolet Q-Jet with different throttle arm and calibration.

Jon.

[Old Goat Racer]

^^^ I thought M6 mite be the date code. So what does the PD stand for ?

[carbking]

Originally Posted by Old Goat Racer

^^^ I thought M6 mite be the date code. So what does the PD stand for ?

GUESSING:

"Picking code" or "plant code".

Carter did NOT use a picking code on the 1966 carbs built for Pontiac, but all of the 1967 AFB's I have for Pontiac DO have a code; and the different tag numbers have different codes.

1966 and earlier, this portion of the tag had an inspector's stamp; but the inspector's stamps were either numbers or special characters such as 34, *, ( etc.

And, the "federal" tags were triangular; the "California" tags were square. All tags were color-coded, but the color would wash out in the first dunking in the extremely harsh carburetor cleaning chemicals of the day.

Jon.

[John V.]

I would call the PD a Manifest Code, same meaning as a Picking Code.

Not sure why it wasn't used for Carbs prior to '67, the 2 alpha character Manifest Codes came about for '65, perhaps they didn't pick carbs by Manifest Codes until '67. Or perhaps, they were marked in some other way without them being coded on the tag until '67. Either way, I believe the purpose was certain. The Manifest for Engine Dress where the Carb was added would be coded for all kinds of things by the assigned 2 alpha character codes.

If sold over the counter, the PD code would have had no real meaning, the Service Carb would have been sold by the p/n. Manifest Codes were only useful for car production at the Assembly Plant.

Kinda chuckling here cause I assumed the M6 was understood by all. Was obvious (to me!) that this Carb was dated Dec '66. I knew that if the only question was the vintage of this carb, the usage was clear.

But I was focused on the question of whether there was any possibility that a 4242S of any vintage could have been O.E. on a '66 engine. For which I concluded, no chance.

Jon, thanks for the added insight. I'm sure you've forgotten more than I know. I have spent much time perusing your website in the past. And reading your post, I now recall reading about the revision codes previously.

On the SA question, do you have anything to indicate how a '62 3300S and 3326S compared with the '63 3300SA and 3326SA?

I understand the revision concept. Seems like that would have made sense for a running change within a Model Year. But I'm wondering if perhaps Carter took leftover inventory of these two '62 carbs and reworked them to the '63 specs (whatever that would have been) and added the A to distinguish them from the '62 carbs. Why else would they not have simply issued a new p/n for these two carbs for '63 rather than making them revisions of the prior year carb? Only time this seems to have been done according to my reference. All other Carter carbs got newly minted Model Nos. each Model Year except for these two and the 3123S that was carried over from '61 to be used again in '62 with not even a revision code added.

Or was the revision suffix more commonly used for Pontiac carbs than is apparent to me?

Sorry for taking this on a tangent, OGR. Just an interesting topic. I have what I believe is a '64 3648S or 3649S. May have been original to the '64 GP I pulled it from although the engine was a 27P (not a GP engine). I assume the GP was originally equipped with a 389 and not a 421.

Someday I'll try to figure out how the carb I have compares to the 3647S (man trans carb) and 3649S (auto trans carb) that was specified for the 4 bbl '64 GTO engine.