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carter 2bbl jets?
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Author:  gato [ Thu Jan 03, 2008 10:54 pm ]
Post subject:  carter 2bbl jets?
i'm just about ready to make my switch to a super six. i've gone thru 2 BBD's. had both throttle shafts rebushed. they are different versions. one has the adjustable metering rods, the other has very skinny meter rods that have no adjustment. the non-adjustable has a plastic hose nipple housing mounted over the accelerator pump. i've never seen that b4.
the place where i got the rebuild kits, and the rebush shop, both tell me these were each setup for a 318.
my concern is what size jets should i have in which ever 1 i choose to use. i think they have jets marked 120 in them now. for the record, there are no holes in the butterfly plates.

anybody know about the jet sizes?

D~~~!
Author:  Rust collector [ Fri Jan 04, 2008 12:45 am ]
Post subject: 
I am pretty sure my slant bbd has 120 jets too....but it has been a long time since I looked at it :?
Author:  daniel_depetro [ Fri Jan 04, 2008 4:30 am ]
Post subject: 
Good information I'll need in the near future.
Author:  Rug_Trucker [ Sun Jan 06, 2008 9:07 am ]
Post subject: 
I haven't seen any with the holes in the butterflies. Probably every carb I have is for a 318 or 273. Two of them might be for a Poly 318. I drilled the jets on one to the next size bit I had. Big mistake!

I could have sworn the jets I have say .055. The plastic vent may be a 73 and newer carb. The adjustable rod ones are even newer.

I have 2 that have no provision for attaching an air cleaner. No vent tube and look like a little toilet.
Author:  SlantSixDan [ Sun Jan 06, 2008 9:45 am ]
Post subject: 
At least the old-style (tall) jets were numbered with a six-digit number. The first three were 120, followed by a dash. So, 120-263, 120-268, 120-575, that kind of thing. Unfortunately, there's no rhyme or reason to the numbers. A 120-263 isn't necessarily one step bigger or smaller, richer or leaner than a 120-264. :-( This is one area where Holley just really got it right: sequential, sensible jet numbers.

Holes in the throttle plates started with the Clean Air Package carburetors first released in large number in '66.

The plastic vent tube started in '70 (California) '71 (49-state/Federal) and was eventually deleted in favour of completely internal bowl venting.

The "solid fuel" BBDs with adjustable step-up rods started around '77.
Quote:
I have 2 that have no provision for attaching an air cleaner.
'65 and earlier 2bbls used a clamp band ring on the underside of the air cleaner, rather than the '66-up bail-and-wingnut system we're all familiar with 'cause it was introduced in '60 on the 1bbls.

'63 and earlier carbs use a choke pulldown piston in a cylinder in the airhorn, rather than the external diaphragm-type choke pulloff.

I've posted a large manual on the Carter BBD carburetor here.
Author:  DusterIdiot [ Sun Jan 06, 2008 7:35 pm ]
Post subject:  Another thing...
Since I was just out 'fiddling' with one of those 'hole in the plate' 1974-318 BBD's... Supposedly the post 1974 BBD's can use late AFB jets and rods... but I've never found any material to corroborate this or I get the " why are you wanting to rejet a BBD...get rid of it and get an AFB..."


-D.Idiot
Author:  Rug_Trucker [ Sun Jan 06, 2008 8:13 pm ]
Post subject:  Re: Another thing...
Quote:
Since I was just out 'fiddling' with one of those 'hole in the plate' 1974-318 BBD's... Supposedly the post 1974 BBD's can use late AFB jets and rods... but I've never found any material to corroborate this or I get the " why are you wanting to rejet a BBD...get rid of it and get an AFB..."


-D.Idiot
I can check that as I have a 600Eddiebrock in a bag. A 70 or 71 AVS and 2 small AFB's. Those are disassembled right now. They look the same as the newer stuff IIRC
Author:  Rug_Trucker [ Wed Jan 09, 2008 7:13 pm ]
Post subject: 
Quote:
At least the old-style (tall) jets were numbered with a six-digit number. The first three were 120, followed by a dash. So, 120-263, 120-268, 120-575, that kind of thing. Unfortunately, there's no rhyme or reason to the numbers. A 120-263 isn't necessarily one step bigger or smaller, richer or leaner than a 120-264. :-( This is one area where Holley just really got it right: sequential, sensible jet numbers.

.
I forgot to check the AFB rods. I was playing with 2 of the oldies last night. One had what looked like the same sized jets as the other. The one I am rebuilding has rods that I checked with the micrometer. About .035" on the fat end, .025" on the thin tip. This one was brass.

The other carb without the place for the wire bale a/c stud the rod was .024" on the big part. And it was magnetic steel! Never saw steel metering rods before.

I think the 120 number is on the rods and jets in my Thermoquad "Strip Kit."

Weird
Author:  75duster [ Tue Feb 10, 2009 1:52 pm ]
Post subject: 
Quote:
At least the old-style (tall) jets were numbered with a six-digit number. The first three were 120, followed by a dash. So, 120-263, 120-268, 120-575, that kind of thing. Unfortunately, there's no rhyme or reason to the numbers. A 120-263 isn't necessarily one step bigger or smaller, richer or leaner than a 120-264. :-( This is one area where Holley just really got it right: sequential, sensible jet numbers.

here.
i have an old carter book that deals mostly with the afb/avs/thermo-quad and it explains carters jet numbering system in it
Author:  SlantSixDan [ Tue Feb 10, 2009 4:14 pm ]
Post subject: 
Quote:
i have an old carter book that deals mostly with the afb/avs/thermo-quad and it explains carters jet numbering system in it
Oh yes? That sounds like very useful information. Can you scan it in? If so, I can host it.
Author:  75duster [ Tue Feb 10, 2009 5:15 pm ]
Post subject: 
i cant scan it but i will copy what it says. its from an old sa-design book "volume two-carburetion:carter carburetors includes thermoquad, afb,avs,and wcfb models." not much about the bbd but it does mention it slightly when it talks about the types of carters.


"Carter utilitizes several part-numbering systems for jets, all of which contain information relating to orifice size, but they utilize a unique encoding. All WCFB's, most AFB's and AVS's and 1974 and later BBD carbs use jets with a three digit suffix that describes orifice size. (All Carter jet part numbers begin with "120-") if the suffix begins with a "3" jet size is less than .100-inch; a "4" in the first suffix position indicates an orifice of .100-inch or greater. Thus a .098-inch jet would carry part number 120-398 while a .101-inch jet would be labelled 120-401." it goes into more detail about AVS/AFB three step metering rod jet sizes since they are different, and thermo-quads are in a class by their own. let me know if you want this info, though i doubt any on here are running AVS/AFBs or god forbid and 800 cfm thermoquad :twisted:
Author:  75duster [ Tue Feb 10, 2009 5:24 pm ]
Post subject: 
Quote:
At least the old-style (tall) jets were numbered with a six-digit number. The first three were 120, followed by a dash. So, 120-263, 120-268, 120-575, that kind of thing. Unfortunately, there's no rhyme or reason to the numbers. A 120-263 isn't necessarily one step bigger or smaller, richer or leaner than a 120-264. :-( This is one area where Holley just really got it right: sequential, sensible jet numbers.

here.
this does not apply to carbs before 1974 and my book does not go into much detail about BBD tuning but i do have one of these style carbs back home... but im in wyoming now for school so that doesnt do much good
Author:  Rug_Trucker [ Wed Feb 11, 2009 5:29 am ]
Post subject: 
While rebuilding the most recent BBD I took a caliper to the rods. I dropped a drill bit into the jets.

The carbs I checked were the "tin top" solid fuel BBD's. One I believe is a '77 318 carb, the others are super six carbs. The jets were the same. The difference is in the rods. One six carb came out of a friends California spec van. I have no idea where the other super six came from. (77 or 78?) I am pretty sure the other is a '78. They have the same rods.

My drills could be a bunch better on size selection. I have 2 copies of the old Dave Emanual book in the shop. When I was in the book store a couple of weeks ago I see there is a new edition out that covers the Edelbrocks. I don't remember if it covers the AVS "Thunder Series."
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