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Tanker
Post Newbie
Joined: Nov 27, 2010
Posts: 7
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 Posted:
Thu Dec 02, 2010 5:27 pm |
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How did you seal the mixture needle so that gas does not leak past where the threads were machined off?
Or is the seal on the needle beyond the threads? |
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MissStrega
Hyper Staff
Joined: Apr 29, 2010
Posts: 187
Location: Sacramento, CA USA (GMT -7)
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Thu Dec 02, 2010 10:46 pm |
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| Tanker wrote: | How did you seal the mixture needle so that gas does not leak past where the threads were machined off?
Or is the seal on the needle beyond the threads? |
Good question.
The needle has a flat machined area before the taper begins. Inside the metering block is an O-ring that provides some tension and a seal.
The real trick was to turn the threads off to the same diameter as the previously turned area. When the needle moves down toward Lean Cut-off the threads 'pop' across the slight grooves left from the threads that gives feedback on the cable letting me know I am about to cut fuel flow off.
I've documented and applied for a US Patent on this process after making some changes, and my husband will be offering this for sale as a package for any Holly 2 and 4Bbl carbs in the 2300 and 41xx series soon.
-Stregs |
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X32Wright
Hyper Postman
Joined: Apr 21, 2008
Posts: 445
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Fri Dec 03, 2010 4:52 am |
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Ahh that's wonderful!! SOlving your problem and then helping others while you get an actual product out! Very nice!
Ingenious solution and makes sense. I thought the manifold chamber was cylindrical and needed a fan/vane solution. |
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MissStrega
Hyper Staff
Joined: Apr 29, 2010
Posts: 187
Location: Sacramento, CA USA (GMT -7)
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Fri Dec 03, 2010 5:31 am |
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| X32Wright wrote: | Ahh that's wonderful!! SOlving your problem and then helping others while you get an actual product out! Very nice!
Ingenious solution and makes sense. I thought the manifold chamber was cylindrical and needed a fan/vane solution. |
Thanks Wright 
The original needle was raised up/down by screw threads. The tapered needle changes the orifice area where fuel passes from the bowl to the venturis. This replaces the static jets and after my road-trip I can safely say that this thing works GREAT!
My original plan was to fashion a method to screw the needle in and out, but the limited clearance and complexity ruled that out, so I went with plan B.
It works and with my changes, the mixture settings will be repeatable to +/- 1/2 standard jet sizes.
I drove 423 miles, mostly freeway and turned in a surprising 22.75 MPG!
This is a drastic improvement over the 15-17 I was getting before.
I could tell be the exhaust note and A/F gauge when the 401 was too lean or rich and after messing about I know I can run around 16:1 Air/Fuel Ratio on level ground all day long as long as I keep the manifold vacuum around 18-19". The next test after my changes will be a run to Nevada. I am going to record the A/F data from the LC-1 on the entire trip so I can better document the various changes made and their effect and results.
Toodles!
-Stregs |
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X32Wright
Hyper Postman
Joined: Apr 21, 2008
Posts: 445
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Fri Dec 03, 2010 6:51 am |
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Ahh very glad to know it works nicely Whats the tolerance for that tapered needle? Would it be betetr if its coated with teflon or rubber for better seal on the venturi? Just a thought Would be interetsing to see any Finite Element/fluid dynamics analysis done on this |
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KG26_Alpha
Hyper Staff
Joined: Apr 03, 2010
Posts: 566
Location: London
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Fri Dec 03, 2010 4:05 pm |
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Hmm next...........
EGT sensor |
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MissStrega
Hyper Staff
Joined: Apr 29, 2010
Posts: 187
Location: Sacramento, CA USA (GMT -7)
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Fri Dec 03, 2010 7:56 pm |
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| KG26_Alpha wrote: | Hmm next...........
EGT sensor |
YUP! and a knock sensor with large red light! |
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