Caille 119(or 79, 88, 109) Carburetor Question

[badhobbies]

I have a question regarding a MS71A Tittleson carburetor (which is also used on Caille 79,88,109).
I have difficulty getting it to running smoothly and I’m unsure if I have it assembled correctly.
There are two plugs in the carb, one in the low speed fuel path drilling and one in the high speed fuel path.
One is a normal plug and one has a very small hole in the center of it. I have the one with the hole in it in the low speed “fuel path”. IS THIS CORRECT? Also, what is the purpose of this small hole?

[Nathan Killian]

If you hare having difficulty having in running smoothly, try to fiddle around with the mixture while its running.  I do not know anything about these motors, but I would guess that the hole is to constrict the fuel flow while it is trolling slower and let the fuel flow better at high speeds so that the mixture does not get too rich at slow speeds or too high at high speeds, but that is just my guess.  Given that it has a reversable prop, I would try it in the high speed position, because you can regulate the speed with the prop anyway.  You could also have ignition problems if fiddling around with the mixture does not work.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[PM T2]

The low speed screw controls AIR flow while the high speed controls FUEL.

The orifice you noted in the one plug is to allow air to flow into the idle circuit so if you have it in the low speed circuit, you’ve got it right. Turning the low speed screw in makes the mixture RICHER because its cutting off air flow.

The high speed needle works like most other needle valves inasmuch as turning it inward makes the fuel mixture leaner.

For initial settings, turn the low speed needle out 3/4 of a turn from close, and give the high speed on to one and a quarter turns out from closed. Use the choke to start the motor, but once the motor fires with the choke closed, open it right away before pulling on it again.

Best operation is on a boat. Running it in a barrel (if you’re doing that) presents problems with prop cavitation as well as cooling water flow. In a barrel they tend to pump water well when first started, but as the water gets churned up by t he prop, especially if ytou try running at higher engine speeds, the pump starts losing its bite and the water will eventually stop draining out of the exit pipe. Boat testing eliminates those issues.

Be aware of the fresh air supply when testing motors. I mean for the motor, not for you. I noticed I had outboards that didn’t want to run worth shit in the tank, and figured out it might be choking on its own exhaust. I didn’t have an exhaust fan on the tank so the smoke just hung around unless there was a stiff breeze blowing. Setting up a big pedestal fan near the tank cleared the air and the motors ran better. Hope this helps.

Best
PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

[badhobbies]

Thanks for the info.
PM T2: Thanks for the wealth of information. I understand the reason for the hole in the plug. I do have it in the correct location. I will try again on the boat instead of the 55 gallon barrel. I pulled the plug and found it was set way too rich with the plug getting black.

Also my cork float sticks and I get leakage because of overflow out the top of the carb vent hole. Everything is clean and should perform correctly. Is there any aftermarket floats that might work better than the originals??

[Tubs]

 

Most likely its the float pin seal in its seat at the bottom of the float bowl. Corrosion from sitting over time affect the seal. Holding the pin as straight up as possible, try lapping them with some toothpaste.   

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[PM T2]

Many antique carburetors can use the modern round black Mercury floats. You would have to drill the centre of it out to allow the float pin to pass all the way through, and also figure out the best position in which to put the float retaining pin/clip.

PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

[Author]

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