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Best way to mount a hall sensor

Old 11-14-2010, 09:55 AM
  #26  
captinjohn
 
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Default RE: Best way to mount a hall sensor

mpascual,
Talking about input...yours is real good. The video is well thought out & clear. Keep up the good work my friend. Best Regards, Capt,n
Old 11-14-2010, 10:36 AM
  #27  
Speedy-Gonzales
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Default RE: Best way to mount a hall sensor

This Webra was originally set up from the manufacturer for glow but never ran. They always came with the option to convert to ignition but the original ignition units (sensor) mounted on the back of the engine and were a piece of crap. The adaptor in the head is for a glowplug but I just take it out and drill and tap for 10mm plug. I have also added a Walbro WT-540 carb. A superior replacement for the original Delorto carb.

You can insert the trigger magnet into the original prop hub but the wall thickness from OD to ID is inadequate in my opinion and the addition of the adjuastable ring makes for fine adjustments once everything is in place. The magnets I use are 1/8" x 1/8" dia. noedymium and I order them from McMaster-Carr. Very strong little buggers and nickle coated to keep them from crumbling when pressing them in place.

I machine two rings. ( See pics below ) One that has tapered slots to fit over the webs on the crankcase for mounting the sensor and then the timing ring that fits over the prop hub. They are both 1.75" in diameter and this sets the gap between the magnet and sensor automatically once everything is mounted. This gap is very important to get consistent timing and spark. Some guys remove the crankcase webbing which I think is a big "no-no". The webs are there for strength and should not be removed or altered. The sensor mounting ring also permits drilling the sensor mounting holes in the ring and not the actual crankcase which I think is another "no-no".

Ring shown on left is the timing ring that fits over the prop hub with hole for magnet. Ring on the right is the sensor mounting ring that fits over the front crankcase housing with tapered slots to clear strengthening webbing. Both rings are secured with ( err...uhmm ) JB Weld.

You may say that this is a bunch of unnecessary work but I am a machinist by trade and I like to do it right the first time. Do whatever pleases your own fancy. I like my way the best. Not really that much more work involved when you have the machinery to work with. It takes me 45 minutes to do ALL the machine work for both rings and the sparklplug.

Here is the link to the magnets.
http://www.mcmaster.com/#neodymium-i...agnets/=9prxj4
Click on the picture showing the square magnets titled " Ultra-High-Pull Neodymium-Iron-Boron Magnets" Towards the lower part of the NEXT page that comes up look under "Disc Magnets Nickel Plated" #5862K61


I have not done this yet but I am going to run a Webra Bully on methanol with ignition to see how it performs.
Old 11-14-2010, 01:24 PM
  #28  
Speedy-Gonzales
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Default RE: Best way to mount a hall sensor

mpascual,
Just curious......what prop make and size/pitch are you using. My favorite is a 3W 19x7 but I can not find them anymore. These are fantastic engines. I get 900 rpm at idle and 8400 tops with the 3W 19x7 with the Walbro WT-540 carb.

SPEEDY
Old 11-14-2010, 04:04 PM
  #29  
Hughes500E
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Default RE: Best way to mount a hall sensor

It's great your conversions are working out well, mine isn't

Old 11-14-2010, 04:48 PM
  #30  
Speedy-Gonzales
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Default RE: Best way to mount a hall sensor

ORIGINAL: Hughes500E

It's great your conversions are working out well, mine isn't

Please clarify. I don't understand what you are talking about. What problems are you having?
Old 11-14-2010, 09:31 PM
  #31  
Hughes500E
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Default RE: Best way to mount a hall sensor

I'm still not happy with any of the suggestions for my particular engine!

I guess I'll have to go with a JB route!
Old 11-15-2010, 06:37 AM
  #32  
triumphman49
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Default RE: Best way to mount a hall sensor

Hi there, not a machinist, & did attempt to locate someone to do a "turnkey" conversion for me & even attempted to locate a machinist to make a collar for magnets - to no avail. This was SIMPLE, quick & painless and if ever so inclined, feel like I can remove parts & pieces without having "damaged" my engine. You might can find a "hi-temp" adhesive, but I'm not expecting that much heat at the front of my engine. Good Luck

T-man49
Mike Brennan
Old 01-31-2011, 11:22 AM
  #33  
fujiman
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Default RE: Best way to mount a hall sensor

triumphman49, pm me on making you a timing ''ring'' for your eng.

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