car runs great , but getting 20 mpg , dont see the rich problem at idle only when running on the road , by the fact you can smell the gas fumes, running b20 with hs6 side drafts, mallory ignition 4 2 1 header with 21/2 flowmaster,motor is 20 over ,from what i was told , not sure on the cam the motor was a back engine for a guy who used to race at limerock , i am not complaining just wanted to try to tune it a little better , the best was these kids in a honda busting my chops to run them light to light , was kind of funny when they were the ones left behind , my son who was behind me couldnt stop laughing at them
thanks for any ideas

If the throttle shafts in your carbs are worn so air comes in around them
at idle, that will make you overcompensate by setting them richer.
This is a pretty common problem. They can be fairly easily rebushed or you can
get oversize throttle shafts from either Rhys Kent in BC (250) 479-5482
or Joe Curto in New York (718) 762-7878. To install oversized shafts you have
to ream the carb to fit. (As you do to install new bushings, different size
reamer).
--
George Downs Bartlesville, Heart of the USA!

Ken,
Before you do anything else, check to see what kind of needles you have in there. I don't think that either DX or KD would give you that problem. Once you're sure what you've got compare their profile with KD and DX on http://www.teglerizer.com/suneedledb/

Bob S.

What are the needles in the carbs?

Good for a B20 w/ HS6 are KD or DX if memory serves. With DX the tendency is to tune tune on the lean side at idle because the profile is wider there than KD, which makes it a little rich at WOT. Maybe give it a flat richer at idle, and see how it does at 4k.

Hi--I had a leak in my (re-used!) intake/exhaust manifold gasket cause the same problem, engine was impossible to tune consistently. No more re-using, nice torque-down of the manifold, no more problem. All best, enjoy the car--Nathan