GOTCHA...............

The throttle bores and venturi size are completely different animals, AND the primary and secondary sizes are ALSO different.
So for a 1.08 venturi carburetor the PRIMARY venturi size which is the throttle bore at its narrowest, that would be 1.080. For a 1.12 the venturi is 1.125.

The throttle bore is 1.437 for a 1.08 venturi carb for BOTH primary and secondary bores and 1.562 for both bores for a 1.12 carburetor

Incidently the secondary venturis sizes are identical for both 1.08 and 1.12 carburetors and they are 1.189 which is the bore out venturi limit for the 4100 hence the rare 1.19 venturi carburetor.

Confusing? it can be if you are measuring the butterflies (which are a few thousands smaller yet)or you are measuring the bores and trying to determine where the 1.08 and 1.12 come inot play.

To further confuse the 4100 Pony's is making a spreadbore carb by installing an insert into common 1.12 carbs reducing both the venturi size and the overall throttle bore size sort of like the old autolite 1100 one barrell carburetor.
Because of the demand for 1.08 carbs to be installed onto small block 289-302 size motors, and lack of real 1.08 small block carbs and the drivability problems associated with 1.12 carb onto these type of motors they have been successful selling this type modified carburetor.

I am not sure ( and not sure if I want to know) how they are identifying these modified carburetors or how they are changing the numbers or if they are.

But my question to you is WHY do you have a pony's carburetor apart? Supposedly (from my dealing with them) if you crack them open you ruin your warrantee on their work. Since they are very expensive and the warantee is one of the reasons they are and one of the best things about their carburetors I am wondering why you have yours apart.

Bill White
White Automotive