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| Schebler Modification ( simple) |
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miro forest
Senior Member
Username: miro
Post Number: 1107
Registered: 11-2001
| | Posted on Saturday, December 05, 2020 - 05:17 pm: | 
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This past summer I had issues with the Schebler carb ( 1 in).
I had the thing out of the boat so I had an opportunity to take a real really good look at it.
The notable thing about this carb, is that it works at all. It's crude and primitive, - patent date 1902, . But 1000's were made and are used today still.
However, I looked at a Marvel Scheble carb I had (also 1 in) and there in the throat of the carb was a venturi.
So I thought - hmmm - maybe a venturi might help the old Schebler work better - better atomisation of fuel.
The Schedler is set up as an UPDRAFT carb.
Here's a pic of the "no venturi" .
I made up a small tube that press fits over the fuel nozzle with an extension up into the air stream.
Here's the tube
The tube restricts the size of the passage by about 20% and increases the velocity of the air, thius lowering the air pressure and sucking in the fuel better.
Looking right down into the carb throat - you can see the end of the fuel nozzle
The turbulence after the small tube hopefully makes for better fuel / air mixing.
The nozzle angle is about 55 degrees.
The tube is a slightly expanded 1/4 in copper tube and the angle is made with soft solder - it just sits there in the throat.
I had some trouble getting the editting right - sorry fr the double pictures
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Chris Spring
Senior Member
Username: chris_spring
Post Number: 85
Registered: 02-2019
| | Posted on Saturday, December 05, 2020 - 06:59 pm: |
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Hi Miro. I am curious as to whether this will help.
As you may be aware,the Adams has a Monarch carb which is essentially a Schebler Model D knock off.
I'm also curious as to what the symptoms were that you encountered this past year since I had a few problems as well.
Good luck with the mod.
Cheers! |
miro forest
Senior Member
Username: miro
Post Number: 1108
Registered: 11-2001
| | Posted on Saturday, December 05, 2020 - 10:52 pm: |
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The challenge I had this past year, was either it would be too rich ( 4 cycling) or too lean (backfire) . I mod'ed the tip of he needle valve to make the adjustment a bit finer, which helped a bit.
But the dang thing was still quite finniky - not behaving like many carbs I've worked on before. Hopefully, this will make it more of a carb.
Right now, the boat is all buttoned up for te winter. Would be nice if one of the guys in Lousiana could give this mod a try.
I suspect that for engine at a show, with no load, , it ain't so critical, but for a loaded engine, well, it might get better with this mod.
miro |
Chris Spring
Senior Member
Username: chris_spring
Post Number: 86
Registered: 02-2019
| | Posted on Sunday, December 06, 2020 - 03:05 pm: |
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I'm in a similar boat....so to speak.
cheers! |
Ernie
Senior Member
Username: ernie
Post Number: 2621
Registered: 01-2002
| | Posted on Tuesday, December 15, 2020 - 04:57 pm: |
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Miro,
The symptoms you described,I fixed on my fan tail when I had it was to use a a 100K volt ignition system. Mazda RX8 coil with a cobbled up sort of Atwater Kent style timer. With a Ford buzz coil I had exactly what you describe above. With the super hot ign system it was real easy to adjust the carb.
Ernie |
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