Early WH 15,18&20 big bore carb internal differences

[coffeeguy]

Are there any major internal differences between the Wh15,18 and 20 carbs( I know jetting is for the different applications). I have read there are some small differences between the Wh20 and Wh22's in the venturi. Am I in the ball park if I switch between the different types but retain the jetting recommended for the motor not what is in the carb? I may have a set of WH46's that I am trying to verify. They have Wh with no other numbers following on top. Casting number 1374 5427-t,b or c. Then the numbers 46-10348 46-20348 46-30258

[tlwjkw]

never had an 18 but tha others yes.. tha 15's with baffles/tubes and such on a BP and/or OP seemed ta be tha choice of tha roundy round crowd.. as for jetting we always started with what tha motor called for.... sometimes is was ok and sometimes not... when it was justa carb change we never noticed a real distinguishable difference.. a difference in some yes but worth tha trouble, not so much.. jmo.

[pcrussell50]

Are there any major internal differences between the Wh15,18 and 20 carbs( I know jetting is for the different applications). I have read there are some small differences between the Wh20 and Wh22's in the venturi. Am I in the ball park if I switch between the different types but retain the jetting recommended for the motor not what is in the carb? I may have a set of WH46's that I am trying to verify. They have Wh with no other numbers following on top. Casting number 1374 5427-t,b or c. Then the numbers 46-10348 (tel:46-10348) 46-20348 (tel:46-20348) 46-30258

I have both some WH22’s and WH46es and the factory manual for each generation. The WH46es use significantly fatter (richer) jetting. Both carb sets for the 2.4/200… Not 100% sure why the big jetting difference since they are both for the same power and displacement.

-Peter

[wogi]

I have both some WH22’s and WH46es and the factory manual for each generation. The WH46es use significantly fatter (richer) jetting. Both carb sets for the 2.4/200… Not 100% sure why the big jetting difference since they are both for the same power and displacement.

-Peter

Possibly the air bleeds are different sizes between the two

[Merc 2.5]

I have both some WH22’s and WH46es and the factory manual for each generation. The WH46es use significantly fatter (richer) jetting. Both carb sets for the 2.4/200… Not 100% sure why the big jetting difference since they are both for the same power and displacement.

-Peter

From my understanding, its the different sizes of emulsion tube that causes the jetting difference,

[coffeeguy]

Thanks for post #5, that gives me a better under standing ( of the mystic ) on why similar models have such varied jetting sizes for similar carbs ei wh15 vs wh 22 for the same size and hp motors, while a wh-46 for example is on several motors and the jet sizes are quite varied depending on the motor with bigger jets going to the higher hp applications with the same carb base, more like tunning a auto carb . Maybe you know this. From various posts I am under the impression the "idle circut" flows the same through all throtle positions so if the idle jets where changed there would bea consistant change in the overall fuel flow,either richer or leaner. Would the idle jet size changes be miniscule and have no real effect on the over all flow or could there be some small result?