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  1. #151
    av8tor1977's Avatar
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    RE: gas fuel with glo plug no ignition

    If you replace that muffler, or take it apart and gut it and braze in two 1/2 or 9/16" i.d. tubes for outlets, you will gain a good bit of power.

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  2. #152

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    RE: gas fuel with glo plug no ignition

    Hi,
    The WT-499 is only a 11.11mm carb. The same size Homelite uses on a 33cc and a new or modified muffler would help. Many Homelite 45cc comes with a 14mm Zama or 13.49mm Walbro carb.

    Dave
    Every day above ground is a good day.

  3. #153

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    RE: gas fuel with glo plug no ignition

    Dave or Anyone else that wants to comment;

    I see that the carb is smaller but it lets enough fuel to pass through to run on mentanol/oil. What carb would you recommend?

    I notice at full throttle the fuel wants to spit out the front of the carb. ? What do think would help with that. I was going to order a new muffler but a friend is making me one out of aluminum diamond plate (for a cool factor ). I think I need one of those tubes that stick out the top of the carb?

  4. #154
    RysiuM's Avatar
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    RE: gas fuel with glo plug no ignition

    It took me a while to read all pages

    Now back to the post #1 - Aero-nut was running his 18cc on regular gas/oil (50:1) mixture with on-board glow. I understood, when glow plug was powered all the time he got good max rpm and steady idle. Is it right?

    If so, does it mean, that if I replace the spark pug with glow plug (with adpater) and run 1.2V battery to it I can use the engine like the regular ignition-driven engine on regular gas fuel? If so, it may be worth just use it like that. 1.2V NiMh battery for a couple flights for sure weights less than any ignition module (4000mAh is less then 1.5oz). Mo hassle with mixing chemicals and messing with carb. That would be the lightest gas engine ever

    So let me ask again the question: How will the regular 18cc - 33cc weed eater engine perform on regular gas mixture (no additions except 2.5% oil) with glow plug powered by battery all the time?

    RysiuM
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  5. #155

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    RE: gas fuel with glo plug no ignition

    I tried it and it doesnt work to well. The engine does not run very good, I belive it is because it is firing way to soon. But if you change to methanol/oil mixture and a different/modified carb it works good.
    That is what I found out but everyone seems to have a different opinion.

  6. #156
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    RE: gas fuel with glo plug no ignition

    ORIGINAL: Fishmasterdan
    I tried it and it doesn't work to well. The engine does not run very good, I belive it is because it is firing way to soon....
    ...
    That is what I found out but everyone seems to have a different opinion.
    Maybe you didn't try hard enough.
    Yesterday I went to Home Depot where I bought brand new Champion plug. After abusing it for a while with big vise I got all stuff out leaving just the case. Then I work a little on my lathe creating an aluminum plug that I tapped 1/4-32 for glow plug. Finally I got glow plug adapter that cost me $1.75 (Champion plug from Home Depot) and some time in my garage.

    I found some old glow plug that I didn't use any more as it lost all platinum due to running glow engine to lean. It still glows when connected to 1.2V tho.
    So I took out my Poulan 25cc I converted lately, changed the spark plug with glow plug and fired it up. Glow plug was connected to two AA type NiMh (RAYOVAC 1800maH each - yest this cheap stuff from Wall Mart) parallel (glow plug takes about 2.2A).

    I kept glow plug powered all the time. Engine fired up like it used to on spark ignition and just run. I didn't even change the carb setting. Engine was idling steady up to 1600 rpm with normal transition to full power at 7400 rpm [X(] - it is 200 more than with spark ignition. I played with throttle running the engine total about 5 minutes. I didn't notice any problems.

    I need to point it out: I run regular gasoline mixture: 1:30 Motul mixed with 93oct. pump gas (Chevron). No other additions, no methanol, no acethon - just gas station stuff.

    Now I am very confused. If I remove spark ignition I will loose 1 lb and for on-board glow I will add 2 oz (one battery is 1 oz). 3600mAh will be enough for 90 minutes of flying. That's something new the lightest gas engine ever

    RysiuM
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  7. #157

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    RE: gas fuel with glo plug no ignition

    Hi Fishmasterdan,
    The chain saw engine has higher compression then the trimmers, which may account for varied success with straight gas. The small WT-499 and restricted muffler would account for low RPM. If you could lower the compression you may do better on gas with stock carb. Removing material from the combustion chamber is about the only way to lower compression. Shaving material off the piston crown would advance timing, which is decent now.

    Dave
    Every day above ground is a good day.

  8. #158

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    RE: gas fuel with glo plug no ignition

    "Shaving material off the piston crown would advance timing"

    Huh ???????????[X(][]

    [:-]
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  9. #159

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    RE: gas fuel with glo plug no ignition

    When you lower the top edge of piston the intake port opens sooner!!!!! I would say....it does indeed change the timing. But if it runs better...who cares!!!! Regards Capt,n
    I never met a engine I did not like !

  10. #160
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    RE: gas fuel with glo plug no ignition

    Guys, quick question - I think it is the rigt place to ask.

    This thread started about running gas engine on gas fuel with glow ignition. Then for 7 pages the discussion went about different fuel mixtures. I did my experiment with the original setup witout mixing special fuel - I just run the engine the same way aero-nut run his engine almost 2 years ago. I did confirm, that my engine run just fine when glow plug was powered all the time. Any one tried the same?

    I tried to run it without battery attached and it was running very rough missing often. On iddle it died when battary was disconnected. I also tried to start it by hand but I was not able to crank it fas enoug to go through the second compression after the first 'puff'.
    I checked the glow plug after 10 minutes of runniong and it was clean and shiny.

    Aero-nut run his weedeater 18cc, I run my poulan weedeater 25cc. Did anyone try this experiment on other engines or maybe can confirm the resul on the same engines?

    I don't really care 'why' it's running. As long as it runs flawlesly I'm happy. And I don't need to mix special fuel or pay big bucks for fancy ignition systems. I am talking about the 25cc gas engine turning 16x8 MA 7400 rpm on stock muffler eating regular gasoline with the rate 1/2oz per minute, and weights 38 oz (including muffler, mount and on board battery) and cost me less than 40 USD.

    RysiuM
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  11. #161
    av8tor1977's Avatar
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    RE: gas fuel with glo plug no ignition

    Uh, whoops...

    Shaving the piston crown will not change the intake timing, it will change the exhaust timing. Also, lowering the compression will not change the ignition timing unless it is operating as a glow engine. In that case, it would retard the ignition timing, as the engine would reach the pressure sufficient for "auto ignition" later. In engines that have a squish band step in the cylinder head area, machining this out will decrease compression without modifying the piston.

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  12. #162

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    RE: gas fuel with glo plug no ignition

    I ment to say transfer ports...but ooops may be wromg there too!!! Ha. Getting "old I guess" Capt,n[:-]
    I never met a engine I did not like !

  13. #163
    av8tor1977's Avatar
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    RE: gas fuel with glo plug no ignition

    Yep, it will change the transfer port timing too!

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

  14. #164

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    RE: gas fuel with glo plug no ignition

    Fence magnet,
    The idea is that chain saws arn't running well on gas with a glow plug ignition because they may have too much compression. This causes combustion to happen early and results in rough running. With glow plug and gas the only way to control ignition timing is with compression. We need to lower compression by removing material from the combustion chamber, because shaving the piston would change port timing. We can't raise the cylinder because it is one peice with the crankcase. Anyway I think that the poor running of saws on gas/glow is excess compression.

    Dave
    Every day above ground is a good day.

  15. #165
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    RE: gas fuel with glo plug no ignition


    ORIGINAL: davewallace
    With glow plug and gas the only way to control ignition timing is with compression.
    Maybe by lowering the temperature of the glow plug will change the timing. Actually I was thinking of adding a regulated resistor to adjust the current and temperature. This should aadjust the timing for different type of fuel.

    RysiuM
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  16. #166
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    RE: gas fuel with glo plug no ignition

    In my original test runs I found that varying the amperage on the plug had little effect except at 3000 rpm and below. See Post # 22 this thread.
    W W Varnado

  17. #167

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    RE: gas fuel with glo plug no ignition

    Glow fuel manufacturers have been adding oil to the fuel to delay ignition for years. It may be an option for you.

  18. #168
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    RE: gas fuel with glo plug no ignition

    Maybe you could make a glow adapter that can screw in or out to adjust compression like the diesel. I would do it but I for some reason don't have a 21 tooth gear for cutting the 1.25mm(it is 14x1.25 isn't it) thread and don't have the money for it right now.
    Somethings are stranger than fishin

  19. #169
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    RE: gas fuel with glo plug no ignition

    Rupurt,

    If you have one of the Chinese Mini lathes from Harbor Freight, Enco or Grizzly you can use the following to get the 1.25mm pitch:

    A-35, B-40, C-45, D-50 gives 1.2502pitch with a % error of 0.0125
    W W Varnado

  20. #170

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    RE: gas fuel with glo plug no ignition

    Several of the glow plug makers have cold and hot plugs. Seems to me that Rossi has a range of about 5 plugs
    TKG
    Too much power is just about right.

  21. #171
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    RE: gas fuel with glo plug no ignition

    Another update on gas fuel, glo plug no ignition.

    ORIGINAL: wvarn1957
    In my original test runs I found that varying the amperage on the plug had little effect except at 3000 rpm and below. See Post # 22 this thread.
    I think I can confirm that. I run the en\gine again (glow plug powered all the time, 93 Chevron gasoline mixed 1:30 with Motul oil - no methanol added). The engne run very stable 7400 rpm max (MA 16x8 Clasic) idling at 1600 rpm with very good transition. After a couple minutes it started to miss and eventually died. Then I couldn't start it again. I thought the glow plug went bed so I checked it. I found glow plug still in excellent shape but was not glowing orange, but rather dark red. The reason - glow battery died on me. I put a new battery and everything went to normal. Engine started after a few turns and run like usuall. I run it for another couple minutes without any problems.

    Conclusion:
    1. After total 20 minutes of runing I didn't notice any wear on engine nor glow plug.
    2. Current on the glow really doesn't matter. Engine fires when it wants to, but at least my Poulan 25 wants to fire at the right time.
    3. When glow plug is to cold engine just dies.

    I'm not going to abuse test my engine any more, as I need it as it is (magneto ignition) for the plane I'm building. However I just bought another Poulan 25cc. This one I will cut to the bones making it as light as possible removing also magneto support and flywheel. Then I will test it as gasoline glow engine for longer time. If it works well, I will have the lightest gasoline setup ever: about 2.5 lb 25cc engine (including muffler, mount and on-board glow) runnign from 10cc fuel tank. Any 'brand name' of that size weights at least half pound more (and costs 10 times more ). The MVVS 1.6 I have weights 33 oz plus 5 oz muffler, + 2 oz radial mount plus 5 oz ignition plus 3 oz battery. = total 48 oz. It was the lightest gas setup I could ever come with so far.

    RysiuM
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  22. #172
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    RE: gas fuel with glo plug no ignition

    MY lightest G26 conversion so far is about 42 oz with muffler, battery prop bolt and nut, and ignition.....I haven't tried to see how far the fins can be cut down and still cool the engine
    RC Ignition

  23. #173
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    RE: gas fuel with glo plug no ignition


    ORIGINAL: RCIGN1
    MY lightest G26 conversion so far is about 42 oz with muffler, battery prop bolt and nut, and ignition
    Man, you must have cut it good - can you see the piston through the case

    What ignition did you use?

    RysiuM
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  24. #174
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    RE: gas fuel with glo plug no ignition

    wvarn1957:

    Thanks but its a Myford ml7, I should have a look and see if some of the other combinations are close enough. The parts for this machine are easy to get but really expensive around here(I have actually been advised that it may be cheaper to have the gear cut[:'(])
    Somethings are stranger than fishin

  25. #175
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    RE: gas fuel with glo plug no ignition

    The mag rotor, source coil, and rear crank extension for the rotor are all remover, about 12 oz....The ignition circuit weighs about 1 1/2 oz....There are 4 mounting lugs on the front of the case that are not used and can be cut off...The cylinder is square and can be slightly machines to lose a little more...The flat mounting plate on the rear can be removed and the engine mounted with the 3 5mm holes that held the plate on....I could use a lighter spark coil instead of the original Zenoah part and a 10 mm CM6 spark plug with a DA shielded cap to save a little more, have not tried that yet...An aftermarket aluminum muffler is lighter than the stock steel one....A 600 NiMh battery will run the ignition for over 2 hours, weighs 2 oz or less
    RC Ignition


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