Have a couple of 1964/65 MoPar AFB carb's that do not have the weighted air valve on the secondary side... I mean they never had one from the day they were manufactured. The secondary boosters are attached at the sides rather than at the back. Every other AFB I worked on had the weighted secondary air valve and the bosters attached at the back. Is this setup common? Are there other years / applications that are that way also?
First off, are you sure they aren't AVS carbs? They look similar, but have an air flapper on the secondary side. If you do know the difference, don't think I'm trying to be insulting - just want to rule out an easy ID. Here's AVS's: The other question is, do they have a real venturi booster, like on the primary, or just the little cheesy tube like an AVS. If it's a real booster, but bolts on from the side, I've never seen one. Best o' luck. And if it don't look like these, please post pics; I'd love to see 'em! -bill
They are AFB's. I know the difference between AFB and AVS carbs... AVS have a spring-loaded air valve over the secondary side. Also, AVS carbs weren't around yet in 1964/65. When one looks down the air inlet opening of the subject carbs, they can see the secondary boosters and below that the secondary throttle plates. No air valve whatsoever - counterweighted nor spring-loaded.
One of them has stamped into the base 3856S J4 indicating it was from a 1965 MoPar with a 383. I also have 3644S and 3871S carbs. When looking down the air inlet, you can see what I was talking about. The second picure shows another wierd feature... ~1/16" dia holes in the carb below the booster venturis but above the throttle plates. These holes go out to unfiltered air... One hole for each venturi and they are on every one of these carbs - so they aren't someone's "improvement"... Any idea what are those holes for?
I just checked my "1982" Carter carb catalog, and it doesn't list any of those numbers. Maybe someone with an older book? Also a thought, 3856S you say translates to 1965 Mopar 383. Those numbers my be numbers that Mopar added, if it was a factory carb. I have an early factory installed Holley from a 58 Ford, that has Ford part numbers on it only, that Holley has no listings for. Just a thought. Those carbs you have are unusual, I've never seen them like that before. Not that I'm and expert.
Thanks for the reply. Is your 1982 book for aftermarket or replacement carbs or does it list OEM applications? I think 3856S and the date was stamped in by Carter, not Chrysler corp. It's the same font and size as other non-MoPar AFB carbs I have.
Maybe it's a Chrysler exclusive--all three carb numbers show up in my chart as Chrysler carbs. Your 3856S shows up under both Chrysler and Plymouth, but the other two only show up for '64-'65 Chrysler 413s.
I just checked 5 AFBs, 59,62,64,and 65 mopar and a 62 chev, the only one with air valves is the chev.
I think the CFM is about 450, but have no idea what the extra holes above the throttle plates are for...
Most factory AFBs of that era were in the 500-550 cfm range. The 400hp 409 AFB was a big deal when it came out because it was rated at 600.
The small holes are "vapor vent holes" that supposedly helped with hot engine starts. I've seen these on mid 60s AFBs; I don't know if they worked or not... party at flamedabone's house? Later Frank
Thanks for the replies. I recently discovered that same chart is also in the Carter Carburetors book that I have. Unfortunately, there is no discussion in that book about those mystery holes. The vapor holes sounds likely, but it seems also like a place to suck in dirt.
I know this thread is 7 years old now, but I got the same question. I have two Carter AFB 3249s carburetors with no air valve, just 4 boosters. The primary and secondary throttle plates are the same size as a 400 cfm unit. I was hoping to use these two carbs as a dual quad set-up for a high duration cammed 354 hemi (ported, headers, you know the drill). I fear that even with the small primary's and secondaries that there will be significant bog on tip in. I noticed that the "high and mighty" Plymouth drag car (newer version touring today, not the original) used these older bodied Carter's and I was hoping to get the same look. I would like to avoid the Edelbrock's, Federal Moguls's and TQ's. I don't have the cash to fork out on what they get for factory dual quads. It was hard enough finding two of the same number carb (2 x 3249s). I am no stranger to Carter's, and have set up some cars with decent performance (help from a wide range O2 sensor, step-up rod covers with holes so I can see the action at idle and snap test, yada yada), but this is the oldest AFB I have worked on. BTW: I do know the difference between an AFB, AVS, WCFB, and TQ. Anyone ever use these old AFB's (without weighted air valves) for a dual quad set up? How do you get around the bog?
Here is a picture of the Carter AFBs on the 'high and mighty' Plymouth. They look like the 1961 3249s carburetor I am talking about in the previous post. How would you get dual quad AFB carburetors with no weighted air valves to not bog on quick throttle stomps? Is it just increasing the accelerator pump jet size, and keeping the step up rod & jet combos on the rich side? That would not be very street able, but then again it is full race... http://s196.photobucket.com/user/rallye72/media/IMG_0642.jpg.html <a href="http://s196.photobucket.com/user/rallye72/media/IMG_0642.jpg.html" target="_blank"></a>
Contact Carbking here on the Hamb. He knows about everything there is to know about Carter carbs. Another option would be to give him a call. http://www.thecarburetorshop.com/
Chrysler used AFB carbs on many of their SINGLE QUAD applications sans auxiliary air valve. I don't remember if ALL of the Chrysler dual quad applications used the air valve, but most (possibly all) of them did. The holes below the booster have the same function as the "looped" throttle body gaskets used by Rochester, to improve drivability in very hot city driving. Here is a link to an article with original Rochester documentation that I posted several years ago: http://www.thecarburetorshop.com/Ventedgaskets.htm I would not suggest using the carbs without the auxiliary air valves in a multiple carb application. HOWEVER! The 3249s was a factory power-pack carb for a 318. There seems to be a lot of demand for these carbs. Do more homework, and figure out what other smaller carbs might have the air valves. Then maybe you can either do a swap with someone (not me, information only), or possibly sell yours and purchase others. As to changing the pump squirters: On the Carter, changing the pump squirters will NOT alter the volume of fuel delivered by the pump, rather it alters the timing of the delivery. The volume of fuel is determined by the volume of the pump cylinder displaced by the pump stroke. The volume may be altered slightly by changing the pump rod position in the pump arm to a different hole. The hole closest to the body will deliver the largest stroke. Also, Carter produced many different length pumps. Using a shorter pump will increase the volume. AS A LAST RESORT: Additional volume may be obtained by milling the pump cylinder oversize, and inserting a larger diameter pump. This is basically a racing only mod. Jon.
Great advise! It is very much appreciated. Do you have a list of these early bodied AFBs with the auxiliary air valves? Where would I research this information? Thanks, Brad P.S. Also, to others on the HAMB, I have some 1961-62 318 Power Pak Carbs for sale...
Brad - most everyone BUT Chrysler did use the air valves. I doubt anyone has put together a list. The information on bill-of-material for each carb can be found in the Carter Master Parts book. Generally, these cover about 7~8 years. Occasionally you find one that has been properly updated, and will cover more. These show up frequently on ebay. If you wish, give me a call to discuss your specific application (the advise is free, although some might say you are paying too much ) Jon.
Just an aside, it looks like these DeSoto dual quad Carter AFB's didn't have air valves either. http://www.forwardlook.net/forums/forums/thread-view.asp?tid=38317 http://www.forwardlook.net/forums/forums/get-attachment.asp?action=view&attachmentid=93432 Posted using the Full Custom H.A.M.B. App!
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