Slant Six Forum :: Matching jets for Carter BBS--need cross referencing help!

Hello everyone,

I have 3 carter BBS carbs, all the same except for the year and jetting. I want to use 2 of them to do an offy 2x1, but I want to match the jetting up so they are going to run the same.

My first preference would be two very lean jets, since I'm already running 2 carbs. In any case, here are the jet numbers:

268S--Carb # 4956: this one I think is a late 60s 170 carb, and this is the leanest jet
263S--Carb # 4198: comes from a BBS from a 65 Coronet
268S--Carb # 4183: 65-66 Dart?

Questions:

*Are the 263 and 268 jets compatible?
*IF not, which is the leanest jet? (so I can find a 2nd one of these)

Thanks!

MJ

Author:	NewLancerMan [ Wed Mar 30, 2005 6:31 pm ]
Post subject:	Matching jets for Carter BBS--need cross referencing help!
Hello everyone, I have 3 carter BBS carbs, all the same except for the year and jetting. I want to use 2 of them to do an offy 2x1, but I want to match the jetting up so they are going to run the same. My first preference would be two very lean jets, since I'm already running 2 carbs. In any case, here are the jet numbers: 268S--Carb # 4956: this one I think is a late 60s 170 carb, and this is the leanest jet 263S--Carb # 4198: comes from a BBS from a 65 Coronet 268S--Carb # 4183: 65-66 Dart? Questions: Are the 263 and 268 jets compatible? IF not, which is the leanest jet? (so I can find a 2nd one of these) Thanks! MJ

Author:	steponmebbbboom [ Wed Mar 30, 2005 6:35 pm ]
Post subject:
Dont forget to look at the stepup rods that fit into those, they also come in different sizes.

Author:	NewLancerMan [ Wed Mar 30, 2005 6:37 pm ]
Post subject:
true true! Forgot to mention, the first two carbs have the same length and diameter rods, so I think I have a match there. Haven't measured the 3rd one yet. To measure them, I just measured the diameter of the "thin" section, the "thick" section, and the length. Are those the correct measurements? MJ

Author:	SlantSixDan [ Wed Mar 30, 2005 7:01 pm ]
Post subject:
263s is larger/richer than 268s. The Carter jets aren't like the Holley ones, in that the numbers aren't sequential in any particular direction.

Author:	steponmebbbboom [ Wed Mar 30, 2005 7:02 pm ]
Post subject:
I don't know. Are you using a micrometer? I would imagine the increments in sizes are extremely small.

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Author:	NewLancerMan [ Wed Mar 30, 2005 7:04 pm ]
Post subject:
Quote: I don't know. Are you using a micrometer? I would imagine the increments in sizes are extremely small. yep they are quite small. I'm using a digital micrometer. I can't recall what they were..something like .028 or so on the small side. Gotta find that piece of paper! MJ

Author:	Dennis Weaver [ Wed Mar 30, 2005 11:17 pm ]
Post subject:	Re: Matching jets for Carter BBS--need cross referencing hel
Quote: Hello everyone, I have 3 carter BBS carbs, all the same except for the year and jetting. I want to use 2 of them to do an offy 2x1, but I want to match the jetting up so they are going to run the same. My first preference would be two very lean jets, since I'm already running 2 carbs. In any case, here are the jet numbers: 268S--Carb # 4956: this one I think is a late 60s 170 carb, and this is the leanest jet 263S--Carb # 4198: comes from a BBS from a 65 Coronet 268S--Carb # 4183: 65-66 Dart? Questions: Are the 263 and 268 jets compatible? IF not, which is the leanest jet? (so I can find a 2nd one of these) Thanks! MJ MJ, why dont you use some wire drills to first find the size of the larger of two jets, then open up the other to that size. Just because you are running two carbs doesn't mean you necessarilly need them to be leaner than they would be with one carb. Other considerations are the idle orfice tube (you'd want to match them) and pump shooters. The different year carbs may also have different dia. air bleeds. Best bet is find two identical carbs. D/W

Author:	NewLancerMan [ Thu Mar 31, 2005 6:51 am ]
Post subject:
I've had a devil of a time find the exact same carb on ebay and elsewhere. I was leery of the remans, so I've been sitting in limbo trying to match them up. I saw a 4183 last week, but was outbid. I don't have small enough drill bits at the moment, but money talks right? I hadn't thought of drilling them. thx!

Author:	Dennis Weaver [ Thu Mar 31, 2005 8:59 am ]
Post subject:
Most any used BBS you find is going to be a reman or rebuilt by someone at some point in it's life. D/W

Author:	Dennis Weaver [ Thu Mar 31, 2005 9:01 am ]
Post subject:
Quote: I don't have small enough drill bits at the moment, but money talks right? www.mcmaster.com ...and they're cheep! D/W

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