I just pulled a spare 1405 (or was it a 1406?
) off the shelf.
A 0.028" drill bit is the biggest that will fit in the orifice. I'm also having an off idle stumble, so I may just drill them out to 0.035"
the 1405 that i'm using for a secondary carb on a ch28 did have a .028" idle jet and the 1406 i use for primary had a .033" idle jet. ironically these two carbs were totally different internally in relation to the clusters and jets. i'm using .036" idle jetting now in both carbs but i do have a little bit of cam in the engine and sometimes that needs a little fuel help. i use nothing bigger than .028" squirters with the orange/tan ( 1467 pump) accelerator pump (carbs came with this pump) and no stumble, hesitations, spits, sputters or nothing adverse. power is very smooth and reliable.
I have a 1406 (I'm pretty sure
) on my truck right now. Apparently 1405s and 1406s have different venturis, boosters and idle circuits?
It's been several years since I've been in the carb. I'll get the tan accelerator pump (thanks for the part number!), then dig into it at some point.
