Intake Pipe Diameter

[71_Bronco 1,072]

I am thinking about fabricating an extended air intake pipe for my Wisconsin motor to allow the air cleaner to sit outside the hood (no room under the hood without cutting).

 

The existing fittings have a 1-1/8" clear passage from the air cleaner to the carburetor.

 

The section I am adding will be in-between 2 fittings, so I wanted to try to match the ID.

 

If I cannot get the right size pipe (1-1/8" ID), would it be okay to go down a little bit? Or is it safer to go up?

 

The next size down that I can easily get my hands on (and cost effectively) is roughly 1" ID (smidge larger, but lets call it 1" for conversation).

 

Thanks

[ebinmaine 72,669]

If the carburetor itself is going to stay bolted to the engine and the pipe that you need to change is the one between the air cleaner and the carburetor, I don't think you need to worry about it too much so I would go one size larger if anything. 

 

I had to do something similar on Trina's Pony tractor when I put the 8 horse Briggs engine in it. 

[71_Bronco 1,072]

1 hour ago, ebinmaine said:

If the carburetor itself is going to stay bolted to the engine and the pipe that you need to change is the one between the air cleaner and the carburetor, I don't think you need to worry about it too much so I would go one size larger if anything. 

 

I had to do something similar on Trina's Pony tractor when I put the 8 horse Briggs engine in it. 

 

The additional tube will be inserted at the joint circled in green below.

 

The carburetor bolts to the engine block, and has a side inlet for the air to come in. Currently, there is an elbow pointing up to mount either a dry or oil bath filter.

 

 

 

[8ntruck 7,833]

You might have some luck looking in the plumbing department for sink drain parts.  I'm thinking that 1 1/8" is one of the standard diameters.

 

After seeing your pictures, it looks like you will need to use brass pipes and solder some flanges made out of brass plates.

Edited October 27, 2020 by 8ntruck

[gwest_ca-(File Mod) 11,479]

Pvc vacuum tubing - sweep the floor kind - has a 2" OD.

They make an end cap for it. Wondering if the cap is large enough it would allow the mounting screws inside of it. Cut a hole for the air to pass in the center. Then you could use their elbows to get to where you want to go.

They also have a flexible tube that is 2" ID to fit over the tubing. They also have short elbows and long sweep elbows.

I used this flex tubing on a remote filter for a Kohler about 5 years ago and it is still in good shape.

[71_Bronco 1,072]

I was going to buy a piece of copper plate from McMaster, and use copper piping for the extension, allowing me to use standard solder connections (something i can do, since i don't have a welder and don't know how to use one).

 

1" copper pipe is 1-1/8" OD and 1"/1-1/16 ID depending on the wall thickness used.

 

1-1/4" copper pipe is 1-3/8 OD qnd 1-1/4"/1-5/16" ID, again depending on which wall thickness used.

 

I can get 1-1/4" OD / 1-1/8" ID copper pipe from McMaster, but there is no fittings I can use to make my turns.

[ebinmaine 72,669]

Smaller diameter copper has been known to be brittle. 

The larger diameter you're looking at will be better longer. I'd try it and see how it goes. IF it leaks you can repair the cracks with solder. 

[ranger 1,798]

8 hours ago, ebinmaine said:

Smaller diameter copper has been known to be brittle. 

The larger diameter you're looking at will be better longer. I'd try it and see how it goes. IF it leaks you can repair the cracks with solder. 

Copper pipe can work harden and  become brittle when subjected to vibration, especially if is carrying an unsupported weight (air cleaner assembly). I would suggest after bending the pipe to shape and before soldering, preferably silver solder, you anneal the pipe to soften it. Then make sure to add a decent brace to support the air filter. Another suggestion to strengthen the connection at the carburettor end would be to find a short piece of copper pipe that is a good fit over the other pipe, cut one end and bend 90* and flatten the two ‘ears’ to form lugs, which when drilled to match the flange on the carb, and slid as a sleeve over the extension before soldering the flange to the pipe, and the sleeve to the pipe, (soft solder will work here), you will have a much stronger joint the ‘sleeve’ only needs to be about 3/8” or so long to do the job.

Doug.

 

[wallfish 18,089]

What about using black steel pipe with threaded nipples and floor flanges on the ends?

If it can go straight out, pinch a piece of pipe between the two parts with longer screws?

Modify a different air filter to fit? Or make a hose to fit something like this? AIR FILTER

Just throwing stuff out there to see if anything sticks or helps with different ideas

[71_Bronco 1,072]

If you look at this picture, you can see that I need to offset the pipe in order to clear the hood.

 

I had thought about whittling down a solid chunk of aluminum and running it straight out as suggested, but I would need to notch the hood (which I'm trying to avoid)

 

And yes, i was planning on adding some kind of brace for the air cleaner once it was mounted up so the weight is not levering down on the carburetor connections.

 

[ranger 1,798]

1 hour ago, 71_Bronco said:

If you look at this picture, you can see that I need to offset the pipe in order to clear the hood.

 

I had thought about whittling down a solid chunk of aluminum and running it straight out as suggested, but I would need to notch the hood (which I'm trying to avoid)

 

And yes, i was planning on adding some kind of brace for the air cleaner once it was mounted up so the weight is not levering down on the carburetor connections.

 

I can’t see if the elbow is touching the hood or not, if not how about fabricating an angled stub and fitting something like a K&N type pancake or cone filter? I think you can buy the cone type with a straight or offset/angled connection. You may even be able to remove the elbow and fit a small pancake type by modifying the filter baseplate, move the mounting/inlet hole to one end and tilt the filter forwards.

Doug.

[Greentored 3,220]

Anything on the upstream side of the carb- bigger is better. You want zero restriction, ideally.

[Pullstart 66,723]

Too bad you’re so far away... I’ve been known to fab a thing or two out of an old set of headers.  
 

 

[71_Bronco 1,072]

1 hour ago, ranger said:

I can’t see if the elbow is touching the hood or not, if not how about fabricating an angled stub and fitting something like a K&N type pancake or cone filter? I think you can buy the cone type with a straight or offset/angled connection. You may even be able to remove the elbow and fit a small pancake type by modifying the filter baseplate, move the mounting/inlet hole to one end and tilt the filter forwards.

Doug.

 

Doug, the horizontal flange (that the air cleaner sits on) is almost touching the hood. Doesn't touch, but is very close. I wouldn't have room to mount a K&N type filter directly onto the carb.

 

@pullstart, your fabrication is what had lead me to try to figure out a way to extend the air cleaner piping. My dad has a Mig welder in his garage, and can weld somewhat, but I'd have to transport this tractor up there to work on.

 

One other method I thought of, was to use the proper size tubing (1-1/4" OD / 1-1/8" ID) and make a series of slits in the pipe to allow it to bend (like you did in your pictures).

[Pullstart 66,723]

Mig welding is simple stuff, just make sure it’s clean!  Welding + rust = it just doesn’t work.  Go for it!