Rochester M Question

[NeverDone50]

I bought a (new reman) Rochester M carburetor to replace my model B. So I got it installed and running, but I'm confused. When I went to tune it, I turned the fuel mixture screw in all the way, but it barely bogged down. Shouldn't it die when its completely closed?

[1project2many]

If the throttle is open far enough the idle mixture screw will have much less effect.

This page has a reasonable set of steps for adjusting the carb.
https://itstillruns.com/adjust-monoj...l-8061119.html

[mr48chev]

1project2many pretty nailed it I'd hope. If the throttle plate is too far open the mixture screw doesn't come into play much.
Sometimes you have to jockey back and forth between adjustments with the idle mixture and idle speed to get it dialed in. if that doesn't work you may have one of those dreaded vacuum leaks.

[NeverDone50]

Update: I did have a vacuum leak. The old B carb only had one vacuum port for the vacuum advance, but the new one has four. I capped the extras but at some point, the port that faces the valve cover (where I cant easily see) the cap came off. Thanks for the link, too. This new carb has a few more bells and whistles than the old one, so I wasn't sure what I was missing on the adjustments. Apparently, I needed to disconnect the electronic choke and i think the fast idle cam set on a higher step when I was trying to adjust. Hopefully giving it another go today or tomorrow.

[1project2many]

Good deal. I seem to have trouble finding vacuum caps that last anymore. Seems like 2-3 years and they're junk. As ugly as it looks, hoses with screws in the ends last longer.