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| Schebler Mod - ver 2 - still simple |
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miro forest
Senior Member
Username: miro
Post Number: 1109
Registered: 11-2001
| | Posted on Tuesday, December 15, 2020 - 02:01 am: | 
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After a number of discussions about carbs, venturis and PV=nRT, I decided that there was not enough "squishing" of the air flow at region around the fuel nozzle .
So I made a collar for the end of the small tube that fits around the end of the fuel nozzle.
The trick on this one is to file a relief on one side of the collar, slip the mod over the nozzle and then turn the mod 180 deg so the collar sits flat in the carb throat.
The collar is about 20%-25% of the area of the throat area. In the first post about this subject, I made a simple error in calculating the area - it's about only 10%, not 20%.
miro
Here's the carb throat no mod
Here's the mod - a collar soldered to the small tube that fits over the nozzle
Here's the mod installed.
The intention ( hope?) is that the velocity of the air flow around the collar increases , thus increasing the gradient of pressure between the outside world and the area around the nozzle, and creating some additional turbulence.
So instead of fuel globules, there might be smaller fuel micro-droplets in the air / fuel mix going into the engine.
Now all I have to do is wait 4 months to try it all out. |
Chris Spring
Senior Member
Username: chris_spring
Post Number: 87
Registered: 02-2019
| | Posted on Tuesday, December 15, 2020 - 07:40 am: |
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Would it not have the opposite effect? My guess is that the restriction itself would cause the airflow to slow and its pressure increase. And it is at this point where fuel is being admitted. Once the air gets past the restriction the air should have a lower pressure due to its higher velocity. To my way of thinking, that would be the better place to atomise fuel.
Cheers! |
Ernie
Senior Member
Username: ernie
Post Number: 2620
Registered: 01-2002
| | Posted on Tuesday, December 15, 2020 - 04:50 pm: |
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What this is doing is creating s simple venturi. The idea is the flow of air is constant for any throttle opening/engine RPM, so if you restrict the flow with a venturi or Miro's handy dandy fuel mix improver the speed of the air increases in that area and when this happens the pressure drops along with the temperature. Basically a Schebler Model D doesn't have a venturi per say. So anything in this area could, might, may sort of help. |
Chris Spring
Senior Member
Username: chris_spring
Post Number: 88
Registered: 02-2019
| | Posted on Tuesday, December 15, 2020 - 04:56 pm: |
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Hmmmm! So having he nozzle sort of recessed like that would be of no consequence? Interesting. Its a simple mod. I'm anxious to see if it works. Here's hoping, Miro.
Cheers! |
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