I have a 1406 on a 318 & it's lean on the main metering and the choke comes off WAY too fast and the choke pulloff (internal piston) is not functioning. Ain't dug into it yet (waiting for Santa to give me a LM-1) ex for richening up the rods/jets & when it's warmed up past the choke stage it's OK. Yeah I'd block them up for a 15 min test or toss in rods w the thinnest "cruise" step