Is my 340 Overcarbed? Avg 5-6 MPG

Thanks crackedback. Yeah, one and two jet sizes is not helping. It is still yellow at 12afr at cruise. Idle was in in the red at 18afr so I richened up the air mixture screws and that was resolved. Idle is sitting at 14.5-14.9afr.

Here are some pics of the current dizzy setup. Both bushings look to be silver not black. I also took a pic of the spare bushings and springs. I may end up selling this carb and going with a 600cfm or 650. Not pulling that plug yet until I talk to my builder and get all of your thoughts. I am not trying to go through this again so if I have to change carbs I am going to get the correct one!

Appreciate the help as always!

Ken

crackedback said

It's ALL in the tune up. It will need more than a jet change is my guess.

Get the initial cranked up and start from there, which bushing on the distributor? Black? You'll need a different one to get it right at idle. I sell them and they work well. If it was tuned on a engine dyno, the in car requirements can and sometimes are VERY different.

I wouldn't worry about changing a bunch of parts, I have stuff with a much larger camshaft that runs well on the street. It's sorting it out that will take some time.

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