340 Edelbrock Carb Adjustment

[MOPARJ]

When i get hard on the gas of my 340 in my 69 Cuda, it seems to release some black smoke out of the tailpipes. I can see it when i look in the review mirror. You have to really mash it to see it. It has a 600 CFM Edelbrock on a stock 340 iron intake. My personal impression is that it is overly rich, but the screws are only turned out 5 whole turns. It's not a ton of smoke, but just enough to notice when i look on the mirror. It has not been rejetted from what I had when I took it out of the box.

Other than that, it runs very strong and idles smoothly and doesn't seem to miss or fall on its face at high RPMs.

Am I correct about over richness or jetting? I have always thought about going to a 700 CFM or thereabouts Holley. Would that be a good way to go, or should I stay with the Eddie and adjust it?

Thanks

 

[Sanguine]

stay with the edelbrock

the idle screws have nothing to do with anything but idle fuel metering

sounds like a needle or jet swap down a size or 2...buy a kit and drop it down until it doesnt do it anymore...a better indication would be to check the plug colour

I run a 625cfm on a 400hp 340...all a bigger carb is going to do is cost you more $

 

[388dart]

A better question is - how does it idle smoothly with the screws turned out 5 whole turns - maybe 1 - but 5?/ I just installed an Eddy 600 on a non-stock 340 and they were 3/4 - 7/8ths.

 

[MOPARJ]

Couldn't really tell you why it idles smooth, as i adjusted it and it idled best at that setting. It would seem too lean if it was 1/2 to 3/4 of a turn out. I think the general setting was screw the knobs all of the way in, then turn them both out three turns and adjust in 1/2 turn increments until it runs to your liking. It seems to work for me. I have close to the same setting on my 318 in my Duster and it runs well too. I don't see the smoke on it though and it is set straight out of the box too; Edelbrock 600. The idle is fine on it as well.

Believe me, they idle smooth, and I'm very particular about getting the motor to hit on all eight like it should, so i would notice any misfires. I put my ear right up to the tailpipe and listen when i tune. Lol.

 

[Sanguine]

idle screws are better set with a vacuum gauge