On the idle mix screws, does turning them out make it leaner or richer? I had always thought in was richer and out was leaner, but I had a guy on another Mopar site tell me it was the opposite. So which is it?

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Rob M
'80 D100 SWB stepside, S6 4-spd OD

On our stock carbs for the SL6 out means richer fuel mix.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

If you take the screw out, you'll see that the end of the screw is shaped like a cone. The end fits into a cone shaped recess, so the further in it is screwed, the more it restricts the fuel flow.

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

There have been a few carburetors (certain Holley 4-barrels, if I remember correctly) that have reverse idle mixture screws that control air rather than fuel flow. But most carbs, including all slant-6 items, are clockwise to lean and anticlockwise to richen.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Okay, thanks guys.

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Rob M
'80 D100 SWB stepside, S6 4-spd OD

Also certain Holley 2300 2 barrel carbs also were reverse idle screw models that were for OEM replacement on Ford Engines. A couple ways to tell for the Holley is either 1) if 'new' it will use a plastic cover over the idle screws to keep them 'calibrated', 2) you can pull the screw out of the metering block the tip of the 'needle' on the screw is dull and rounded, whereas the regular idle versions have a sharp 'point' to them.

A while back I had installed a Holley 2300 0-80179, that was reverse idle screws and used the economaster venturies, if this was easily convertabile to a standard metering block, it would have been a good 'street' carb, the reverse idle screws just didn't have the 'window' of tuneability to keep things 'right' for the 225.

-d.Idiot