Why are there differences between a carb (say a Ball & Ball BBD or BBS) specified for a /6 with a manual transmission and one for the same engine with an automatic transmission? If it's external linkage, can anybody post comparative pictures?

(I'm sure this was asked before by somebody a long time ago but I can't find the post!!!!)

Sometimes it is linkage hookup, sometime jetting. In some cases, 1965 Valiant, for example, the carb specified for a 170 standard shift is a smaller carb then the one specified for an auto trans.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I can't think of any linkage differences between manual and auto-trans slant-6 1bbl or 2bbl carbs. Until 1966, the 170 (and taxi-spec 225s) used 1bbl carbs with a 1-9/16" throttle bore while the 225s got carbs with a 1-11/16" throttle bore; starting in '67 the larger bore was used on the 170 as well. For manual vs. auto versions of the same kind and year of carburetor, there are usually slight differences in jetting and in placement of the spark advance port within the throttle bore. There are also many different venturi sizes across multiple years and applications.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I stand corrected Do not know about other years, but 65 and 66 170 auto engine got the "big" 1 11/16 carb. My 65 Valiant stocker got bounced in tech, after setting a national record, for haveing the big carb (even thuogh their spec book said that carb was correct). After I sent NHRA, the factory info, they agreed with me, and said they were sorry. But they still didn't award me the reord.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I wondered if the manual trans and auto trans had different power drags on the engine (variation of power loss in the box with engine speed) and the different metering jets or vacuum kick drill sizes compensated for this in some way......

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1969 Valiant Barracuda (/6 from South Africa, RHD)