Carb question

[propane1]

The carburetor float on my Case 446 B43M Onan engine is made of a strange material. Some things I’ve seen mentioned in where ever you find information on these Carburetors is that most say to use a brass float. What is the difference between these two floats and why should you use a brass float. ?
Thanks

Noel

[myerslawnandgarden]

The carburetor float on my Case 446 B43M Onan engine is made of a strange material. Some things I’ve seen mentioned in where ever you find information on these Carburetors is that most say to use a brass float. What is the difference between these two floats and why should you use a brass float. ?
Thanks

Noel

Hello Noel,

The gel-coated styrene float that was used in the DD series carburetors back in the day worked fine until the advent of ethanol enhanced fuels. As there is little clearance between the float and the walls of the float bowl on that carb, just a little swelling from the ethanol will cause the float to drag against the bowl wall either in the up or down position. The brass float is much smaller for clearance and resistant to alcohol solving that problem. Cummins thinks the float is platinum, not brass so I source them directly from Zenith who now owns Marvel-Schebler. You also need to install a buoyancy spring with the brass float, I include instructions for correct assembly.

https://www.casegardentractorparts.com/b8flnews.html

https://www.casegardentractorparts.com/c1spfl.html

These will ship to Canada by USPS 1st Class Package International for $15.75 USD, as this is a special rate not shown on our website I need your postal code prior to ordering to make that pricing available.

The carburetor top cover and air cleaner gaskets are also in stock if needed.

Bob

[propane1]

The carburetor float on my Case 446 B43M Onan engine is made of a strange material. Some things I’ve seen mentioned in where ever you find information on these Carburetors is that most say to use a brass float. What is the difference between these two floats and why should you use a brass float. ?
Thanks

Noel

Hello Noel,

The gel-coated styrene float that was used in the DD series carburetors back in the day worked fine until the advent of ethanol enhanced fuels. As there is little clearance between the float and the walls of the float bowl on that carb, just a little swelling from the ethanol will cause the float to drag against the bowl wall either in the up or down position. The brass float is much smaller for clearance and resistant to alcohol solving that problem. Cummins thinks the float is platinum, not brass so I source them directly from Zenith who now owns Marvel-Schebler. You also need to install a buoyancy spring with the brass float, I include instructions for correct assembly.

https://www.casegardentractorparts.com/b8flnews.html

https://www.casegardentractorparts.com/c1spfl.html

These will ship to Canada by USPS 1st Class Package International for $15.75 USD, as this is a special rate not shown on our website I need your postal code prior to ordering to make that pricing available.

The carburetor top cover and air cleaner gaskets are also in stock if needed.

Bob

Thanks Bob. Thanks for the explanation. I use high test gas only so I think there is no ethanol in that fuel. But who knows for sure. Any way. I’ll think on that. And thanks for the pricing on parts. I also would like a price on the rubber tube that goes between the crankcase ventilation tube on the engine to the bottom of the air cleaner. Can’t remember what that is called.
I’ll look on your web site for your email.

Thanks, Noel

[propane1]

So now I’m wondering what the idle mixture screw and the high speed screw starting settings are.
I soaked the float in gasoline in a tub for a day and a half, then measured it and the carburetor. It looks like there is enough room for the float to work all right. Why I did that was, I wondered if the float would soak up gasoline and sink. It did not. So I think the float will work.
Today I cleaned some things and I’m going to put the idle mixture and high speed screws back in tomorrow. Hopefully. So I’m just wondering what the starting setting are for these two screws.
Thanks again Bob for your information.

Noel

[JSinMO]

So now I’m wondering what the idle mixture screw and the high speed screw starting settings are.
I soaked the float in gasoline in a tub for a day and a half, then measured it and the carburetor. It looks like there is enough room for the float to work all right. Why I did that was, I wondered if the float would soak up gasoline and sink. It did not. So I think the float will work.
Today I cleaned some things and I’m going to put the idle mixture and high speed screws back in tomorrow. Hopefully. So I’m just wondering what the starting setting are for these two screws.
Thanks again Bob for your information.

Noel

Noel, I just happen to have the shop manual for that engine. Here is what it says;

Bob @myerslawnandgarden may have better information from practical experience.

Hope that helps!

[propane1]

So now I’m wondering what the idle mixture screw and the high speed screw starting settings are.
I soaked the float in gasoline in a tub for a day and a half, then measured it and the carburetor. It looks like there is enough room for the float to work all right. Why I did that was, I wondered if the float would soak up gasoline and sink. It did not. So I think the float will work.
Today I cleaned some things and I’m going to put the idle mixture and high speed screws back in tomorrow. Hopefully. So I’m just wondering what the starting setting are for these two screws.
Thanks again Bob for your information.

Noel

Noel, I just happen to have the shop manual for that engine. Here is what it says;
IMG_4479.jpegIMG_4481.jpeg

Bob @myerslawnandgarden may have better information from practical experience.

Hope that helps!

Thanks Jeff

[propane1]

So, carburetor is back together. Screws set, started engine, and set the idle mixture. Got it running reasonable. Then set it so it will rev up from idle to full speed with out hesitation. Idle mixture screw has to be a little rich, so there is no hesitation. So alls good for now. I will have to take it out and put a load on it to see how it works and if it stays working.
So thanks very Bob and Jeff for your information.


Noel

[propane1]

Here I was looking for carburetor idle mixture and high speed screw settings and here they are on the air breather cover.

Noel

[DavidBarkey]

You got a good one there . Most are no longer readable ore have been painted over from the ones I have seen . I can tell you that every flat head I have worked on needs about an 1/8 to 1/4 turn more rich to run properly under load . Part I think is the crap fuel we have these days and part is the carb shafts being a little worn and letting in a little too much air behind the ventury and partly the nature of the flat heads as the age . A lot like us older fellas , need a little richening up to get to work .

[JSinMO]

Here I was looking for carburetor idle mixture and high speed screw settings and here they are on the air breather cover.

Noel

I forgot all about that. I know at least one of mine is readable, maybe both. At least we know where to get the info in the future!