It's been a month since you guys agreed that my new engine is running too lean and that a set of KD needles would be better suited for the 2130 block than the stock B18 needles.

As chance would have it, I disassembled the carbs (for the first time) and discovered that they're already outfitted with KD's!

The process uncovered mostly dissapointments. On the good side, the needles were not visibly worn at all, nor were the jet openings. Unfortunately, I also discovered that the throttle shafts are fairly loose, that the rear dashpot spring has been stretched, and that with fresh Marvel Mystery the pistons don't drop at exactly the same rate (the rear drops more quickly, due at least in part to the increased spring force).

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In addition to the pair of 3-bolt HS6's that came on the car, I have 2 additional pairs of SU's... Another 3-bolt pair in rough shape (crusty, moving parts don't move), and a 2-bolt pair in dirty but OK shape.

Before I invest a bunch of time into one of the sets, I was wondering what the differences are between 2-bolt and 3-bolt carbs?

Are they identical aside from the obvious different number of air filter bolts and the fact that they're threaded on the 3-bolt version, vs. THRU holes on the 2-bolt?

Thanks BBers.

vh.