Idle mix too lean?

[Sailormike]

First I want to thank Don, et. al. for supplying such a great resource for these little motors. I have only discovered this site a week ago and have already learned a great deal.
Here is my situation. I just aquired a 73'colombia 30 from a marina auction and my first priority was to get the a4 running. Since the boat has been abandoned for (?)years I was doubtful that it would ever run. The valves were stuck and I was able to free them up with some mmo. I removed the fuel tank and thoroughly cleaned. Replaced the fuel lines. Installed a new racor. The fuel pump appeared to work fine so I left it. I rebuilt the carb with a kit that was on the boat. And after a little tinkering and tweeking I was amazed when the thing actually fired up. It obviosly was not happy after bieng awakened after a long nap, but after about 30 min it smoothed out and actually runs pretty good, except...
The motor starts fairly easily and after it warms it will idle. But, if I goose the throttle at all it will die. Also when it is in gear and I back down to idle it will die, such as pulling into the slip. Even after it has warmed up good it will not restart without using the choke or at least goosing the throttle while cranking.
I have adjusted the idle mixture screw a dozen time in both directions to no avail. It just doesnt seem to have any effect. Im just not sure what to look for from here??? I dont have a tach (on my list of things to get from moyer) and I have tried increasing the idle speed, but this only helps a little and is iddling too high by the time it does help.
Why is the mixture screw not responding?? Or am I barking up the wrong tree??
Thanks in advance for any input
Mike

[MikeB.330]

Mike,
I would remove the carb again and check the float valve to make sure it is seating. The next time you have this problem check for raw gas in the carb body.

Mike

[Sailormike]

Thanks Mike
Ill check that today
I did a little more searching on this board and read something about a tube that runs through the middle of the carb that must be sealed properly in order for the fuel to be drawn up to the idle jet.
Is there a way to test for this??
Would a light coat of permatex on the gasket ba acceptable??
Thanks
Mike

[Don Moyer]

Mike,

Congratulations on getting this old soldier back into service. All your current symptoms can easily be explained by dirt/corrosion within the jets and nozzles of your carburetor. Before doing anything more serious, I'd remove the carburetor and give it a thorough cleaning.

Don

[Sailormike]

Thanks Don
That makes a lot of sense. When I re built the carb there were some parts that would not come apart without the risk of damage, so I just used liberal amounts of cleaner.
I was looking at your price for a whole new carb and thinking that it might just save me $500 in time and aggravation/gelcoat to go ahead with a new carb. Do I need to order anything else, or is the new carb ready to go?

[Don Moyer]

The new carburetor is complete with a new flange gasket. You simply move your flame arrestor and scavenge tube over from your old carburetor and you should be ready to go. The most you may need to do is to fine-tune the idle mixture a bit in either direction from the factory setting.

Don

[Don Moyer]

Mike,

In general, we don't recommend any sealer on the carburetor main bowl gasket. If you suspect that you might be drawing some air in around the idle passage way at the junction of the main housings in the very center of the carburetor, it's better to flatten the surfaces of both the upper and lower housings until they come together completely.

Unfortunately, there's really no way to positively segregate an air leak at this point in the idle system once the carburetor is together. However, if you can turn your idle mixture screw all the way in while at idle RPM (cutting off all air from the normal channel) and your engine doesn't stop running from too much fuel, there's a very good chance that this junction in the idle passage is drawing in a bit of air to mix with the idle fuel stream.

Don

[Sailormike]

Good news
With a little more care, the right sized screwdriver, and a small piece of wire I found some trash in the idle jet. Now she purrrs like a kitten, and idles perfectly!!!
Ill pass on the carb for the time until I see how this one holds up. Meanwhile ill call this week to order some other things.
Thanks for the help