View Full Version : carter afb

03-06-2000, 07:09 PM
how do i hook up the electric choke on my carter afb carb?
how could i find the cfm for my carb?
also how do i set those large air screws in the front , i think my vaccume
lines are all mixed up , a buddy of mine tuned up my car for me (yeah
right!). I need some help on how to set the air fuel mixture screws and the
elec. choke. also if someone has a vaccumme tube routing diagram , it would
be excellent , thanks

03-06-2000, 11:41 PM
Duster, send me the part number or post it, ill look it up in my book. Usually the second number in the part number is the CFM in hundreds. being 500, 600 or 750. The 625.s are spreadbore patterns, two small, two bigger. Some say there were 400's but I dont think they are listed like that, due to the way the were measured back then. Those air bleeds in the front are tricky. Ill look it up tonight.

Richard Reardon
03-07-2000, 06:04 PM
FYI, I was into a 20 minute technical writing to you about this on AOL last night and the SOB of a thing said "good by" and threw me off the connection. Needless to say an AOL rep. and myself have had some "suttle" words. This wasnt' the 1st time.
I've got a couple of questions.
1. How many vacuum lines are you talking about?
2. What is your vehicle/engine combination and what year?
3. Have you got an AFB or an AVS Carter. The AVS has a "butterfly" over the primaries and the 2ndaries. The AFB only has one over the primaries.
As for the electric choke, I believe you need to have a 12 volt source that is active only when the engine is running. don't use anything off the coil. You need to locate a "hot" wire under the hood that shows ~ 12-15 volts only when the engine is running. Actually, I like the mechanical or the manual choke types over these electrical types. It's just preferance.
When you turn the key the choke should close. I'm not sure exactly how it gets to the open position when things warm up. It may be an electrical/mechanical set up.
Carters are "not user friendly" when it comes to knowledge via the general public. Seems Carter thinks there is a big secret as far as their ID numbers go and cross referance information that's made available by them. All in comparison to Holley of course!
The cfm rating is tough on these unless you happen to have data that isn't readily available. I need to know the answers to the questions I've asked above before I can get into it. Then I can give you some info on how to find out what you have.
Regardless of what Carter it is, this is how you adjust the 2 big "air" screws on the front base of the carb. They both adjust the amount of air going to each side of the carb primary idle circuit and involves how much air is let into the idle circuit to mix w/ the fuel, @ idle only.
With the engine off, hand screw both screws all the way in so they are just snug. Some carbs may require the use of a screw driver. If the screws are really tight, take each one out and put some light oil on it, don't loose the set retaining spring, then put it back. Mark 'em somehow if you need to.
Now back each screw out 1 1/2 turns-exactly.
Start the engine. Turn the screws in one @ a time very slowly 'till the engine starts to run a little rough. You must do this slowly. As soon as roughness is realized, back that screw out 1/4 of a turn. Repeat this with the other screw. You're done. If you had a vacuum gauge, I think you'd be set when you realized the highest vacuum reading taken off a vacuum port leading to the carb base below the throttle plates.
You may find the carb is adjusted as you initially set it, @ 1 1/2 turns out. If it runs best here, leave it.
If you have stumbling, bucking or other problems, don't bother fooling w/ these idle screw settings. You need to play w/ the accelerator pump setting and or the high speed circuit. Carters are a very good and reliable street or strip carb. You shouldn't have any problems w/ it once it's set properly and the vacuum lines are hooked up correctly.

e-mail me @ Rich_Reardon@tellabs.com if
you can use more info.


ps I have a lot of "unknown" cousins up there in the West Calidonia part of N.S. My great, great aunt, my mother, grad mother and a flock of uncles grew up there in the late 1800s / early 1920s.

03-07-2000, 11:49 PM
the engine is a 360 , 1976 i believe. it only has a small balancer on the front though(mabey a good crank?) , anyway , the carb is an afb i think , cuz it has it stamped on it somewhere , i cant remember where now though. My car is on the south shore , while i am here in the city http://www.moparchat.com/ubb/frown.gif it is a square bore , 4 the same size(right?). the car is a 71 duster 4spd with 3.91 posi. I hauled the 318 out for the 360 and im not impressed, of coarse the 360 really needs a tune up. i dont know where to run the advanced spark from. The only tube right on the carb is the fuel line and the pcv.

Richard Reardon
03-13-2000, 06:20 PM
Those '76 360s came from the "smog" era. Don't expect wonders out this thing wo/ some performance mods. The stock "non-smog" '71 318 was probably close to being equal w/ the '76 360. All 360s had "smaller" intake valves than the 340s. The only performance you'll realize outa this "slug" is the torque advantage from the increase in cubic inches. Now a 360 w/ the early 340 heads, cam and other related components, now you're talking! Ya know, like night and day!
That AFB is apparently an after market piece, as I believe Carter "spread bore" type carbs were used on the 4-bbl equipped 360s. I don't know what was used on the 2-bbl versions. The typical AFBs had primaries of 1 9/16ths inch and 1 11/16ths 2ndaries. These ARE NOT considered real spread bore carbs. The TheremoQuad spread bore has primaries about the size of a US/Canadian quarter dollar piece and 2ndaries of 2 1/2 inches. Holley makes them too.
If your AFB has 4 bores all exactly the same in size, it's a 400 cfm unit and no wonder you're not realizing a performance increase. All 4 bores would have quarter size throttle plates. A 500 cfm Holley would be better.
As for your vaccuum advance hose, it should run from the vacuum advance canister on your distributor to a vacuum nipple on the <base> of the carb. It can be in front, either side or maybe even in the back. I don't know of any carb that does't have @ least 1 vacuum port for the dist. vacuum advance hook-up.
If you can find a '68 to '71 340 buy it, rebuild it and trash that slug. A stock 340 will run circles around any stock 360. All 340s '68 to '71 were non-smog, had ~ 10.25 compression and had 2.02 X 1.60 valves. All had 4-bbl carbs too, starting with Carter 615 cfm AVSs. In '71 they went to 800 cfm ThermoQuads. W/ the torqueflite and 3.90 to 1 final drive you're look'in @ 14.5s @ 95 mph in the 1/4 or better. They can be tuned to run 14 flat and closer to 100 in the 1/4 w/ that rear-end ratio.
Look through some of the older postings, there is a lot of info you can find, some of it mine.
Good luck, Richard

03-13-2000, 08:38 PM
i found a spot where it is stamped on it that it is a 625 cfm.

03-13-2000, 09:05 PM
If memory serves me right, around the era that you are talking about if you are using the stock electric choke there was also a resistor hooked in line with the choke?
??????? Part # 3656730 ??????????

03-14-2000, 05:35 AM
Just bought a new electric choke 625 Carter AFB for my 318 yesterday. This carb is not a square bore, the secondaries are slightly bigger than the primaries, but not as much as in a spread bore. Anyway, the choke has tow terminals and in my case they are marked for + and -. The one with male terminal is + and the one with female terminal is -. The + should be taken from a source that is on only when ignition is on, but not from alternator or coil. It must get full 12 volt. Then in my case there is a vacuum connection in the bottom of the housing; this is only for the choke to get clean air, and it will go to a pipe above the secondary throttles on the same side as the choke housing. I installed the 625 in to my 'no buck 318' making it even less no buck, but boy does it work well. The Holley spread bore double pumper previously in the engine would have needed a lot of adjusting to make it work properly; I got tired of that and bought a new carb. Now there is no hesitation even when the engine is cold, in this case the first feelings of the AFB are very encouraging.

03-14-2000, 05:53 AM
I have had good luck with the AFB's. I ran one on my '74 Sattelite for 100,000 miles(225,000 total). It worked well with only one required rebuild. I bought it used with who knows how many miles on it. It came with a LD340 intake I bought for $150 back in '89. I ran it with an open element air cleaner and only iced it up three times. Once pushing snow up over the front bumper until the headlights were covered. Another time driving in a blizzard, had to look out the side window to see the road. The third time was during a sharp cold spell, -18°f with a 15-20 mph wind. It died about 25 miles from home. My brother-in-law came out to get me with his Ford pu. It died and we fixed the icing in the needle and seat on the Mopar to get us home

Richard Reardon
03-14-2000, 05:50 PM
That's interesting about the "cfm" rating being stamped on the carb. The only Carters I've ever seen w/ the cfm rating clearly "advertised" are the "Competition Series" AFBs. I have a nice re-built 500 cfm unit and a 625 I haven't done yet, both are Competition Series types.
More on the bores, the 750 cfm units also have identically sized primaries and 2ndary bore/throttle plate sizes. I believe all 4 "holes" to be 1 11/16ths inches across.
As mentioned, the 600s and the 625s have primaries of 1 9/16ths" primary bore sizes and 1 11/16ths" 2ndary bore sizes. The 500 I have is configured the same, where the 2ndaries are a tad bigger than the primaries, but I'm not sure of the exact measurements on this one. And of course the 400s had all 4 bores the same size-about the size of a quarter, US or Canadian!
The 2 electrical connections is correct, I forgot there was 2 of them.
I think it may work this way. As electrical current heats the resistor, (there is more resistance w/ heat build up) hence voltage drops off, due to the resisted current flow, the choke plate begins to open.
That 625 on the 318 is an excellent choice, BTW. The good thing about Carters is the way they use the counter-weights to "realize" vacuum to initiate 2ndary opening. The 2ndaries will NOT open, 'till there is demand via the engine, hence over carburation using even huge cfm rated carbs on small cubic inch engines is practically non existent. Hence, the 800 cfm ThermoQuad useage on the "little", '71 on, 340s.


03-14-2000, 08:00 PM
my carb is exactly as described by dartGT66, i will try it that way and see if it helps , thanks to all for their knowledge.

03-14-2000, 08:01 PM
my carb is exactly as described by dartGT66, i will try it that way and see if it helps , thanks to all for their knowledge.