Inliners International Forums General Discussion Engines Idle Speed - Dual Rochester DC Carbs

Ted,
Sounds like you have the "S=Small" size BC carbs (they come in XS, S, M, L, and XL sizes!)
Have you tried richer jets, say #54 instead of #51?

I usually run the M=Medium or XL=XtraLarge jugs, but once ran the XS=XtraSmall carb and it liked a much richer mix than the factory setting.

Only other thing Ive had trouble with is, the seal from block to intake (tho I have the newer six which may be trickier). Sometimes they seal good cold but when they get hot, a leak develops and the idle goes bad.

Or, try a couple different carbs, those B/BC/BV carbs are still pretty cheap at the swap meets....