hey ron i have a question about the carb seating as well, i just received my new b5 from amain today and went to put the carb in..wow that puppy is tight..anyhoo i too can not get it all the way down...now im not sure how "flush" its supposed to sit i have refenced it to a few motors i have axial/ofna... and it looks like you can still see the top or first o-ring between the carb and the block...its squished between the 2 but theres a tiny gap between the carb n block...is that normal or should it be metal to metal and not be able to see possible the oring a tiny bit.. im talkin maybe 1mm or less...prolly less