Primary Rod Identification Question

[aajc71]

Hi.
This is my first post here.
Can anyone please explain what the difference is between the primary Rods lettering? Eg 49, 49k 49p.

Thanks for any responses in advance

Cheers


Andrew

[Shark Racer]

The number is the maximum width of the tapered section. The letter determines a couple of characteristics.

B&C rods are for earlier carbs and are a different length than J/K/M.

The B,C,J,K rods have a .026 power tip and the Ms have an .036 power tip. The power tip is the section applied during heavy throttle, so basically determines WOT metering on the primary side.

I'm sure there are more variations on lettering; I really don't know them all and would love to know more myself.