The Home Machinist!

Hi, we have 1 1/2HP FBM engine S/N 444830 Built. 1920 all the parts are there, good spark etc, the problem is someone converted it to a B/S carburetor which does not work, it’s been rebuilt and still leaks, we have good intake suction, has anyone attempted to reto a carb to one of these engines? Thanks
Geo

Geochurchi wrote: ↑Mon Feb 22, 2021 11:08 am has anyone attempted to reto a carb to one of these engines?

Is that a typo (reto), or are you asking a question about which I know nothing?

H

How about retrofit, and probably should be FM for Fairbanks Morse.
ALL LIVES MATTER!
Geo

Thanks for the clarification. Much better.

A tip (please accept this in the spirit it is offered). If you hope to get good advice, it really pays to not use shortcut language. Spell it out and provide details so readers understand what you mean. Let the readers know it's important to you by spending enough time to do so. If you ask questions that are unclear, you shouldn't expect to get worthy advice.

H

Is that a Model Z? Not much of a picture to judge from. Pretty sure that engine is designed to run on kerosene. Probably didn't have a true carburetor but rather a “mixer” Need to clarify what you mean by “B&S carb doesn't work”
Sitting there and drooling fuel you have a needle/seat, float height problem.
Whether you can make it run well with that carb I don't know. Should be able to make it try and run pretty easy though.
It just needs gasoline vapors sucked in to fire....

I agree with Bob D., the engine should be runnable with that carburetor. I don't have experience with that specific engine, but over the years I've seen old engines that were fitted with modern carburetors. We once had an Associated Hired Man (2.25 HP, as I recall) that had been fitted with an updraft carb (probably from an auto or tractor) and it ran fine.

A few questions:
1. Does your engine have a fuel pump, or does it rely on gravity feed or suction?
2. When exactly does it start leaking? As soon as you put fuel in the tank, only when the engine is cranked, or ?
3. Does the engine fire at all?
John

Hi, No fuel pump, leaks when engine is cracked, it will pop if. Put a bit of gas in the cylinder, apparently it did run fine years ago, I have never seen it, one thing I may try is lowering the gas tank as it is now it’s more of a gravity feed

If it doesn't leak when it's just sitting there with fuel in the tank and you're not cranking it, that suggests that the carb needle & seat are OK and the float is not stuck in the "open" position. It leaks when you start cranking. You've clarified that there's no fuel pump, so it can't be that a pump is forcing fuel into the carb and overpowering the float.
Is the fuel dripping/running out of the air intake? If that's the case, then it suggests that too much fuel is being drawn in during the intake stroke. Try closing the needle valve and opening the choke wide, to see if the leak stops or at least decreases significantly.
John

Edit: I looked at the pictures again and was reminded that the carb is fitted with an air cleaner. You might want/need to remove it to facilitate debug. Also, can you post another picture or two, zooming out a bit so we can see the entire front of the engine and maybe one of the entire engine itself.

I think the fuel leaks out of the bottom of the carb, I’ll have to check that, no fuels ever gets into the cylinder, plug is always dry.
It maybe awhile before I get back to this, any suggestions are welcome, apparently this carb is problematic in other applications.
ALL LIVES MATTER!
Geo

Not sure if you saw my last edit, but some additional pictures would be helpful. From the pictures you've posted, the location of the carb relative to the intake valve is interesting. Can you zoom out a bit and post a picture showing the entire head and carb.
John

I can take better pics but it may take awhile.
ALL LIVES MATTER!
Geo

"...leaks when engine is cracked..."
What is cracked? The cylinder? The throttle? Clarity please.
RussN