[Luke Planemaker]

Thanks for confirming that, I'll pull the muffler and plug to figure the cc's. Almost hope the electrical is shot, but can use a spare saw more than a spare engine right now.
Shortened linkage on skidsteer and ran it on glowplugs again. Runs great for about a minute, then stumbles a bit when warm. A little choke smoothed it out again, so I think fuel problem. Need to find a transformer or something that can drop 12V down to 3 for plugs. Using old glow plugs too.
Here's some pics of it idling on glow plugs, thought something would be blurred, but camera must be darn fast. One belt needs replacing and fuel filter will be moved away from exhaust.

[Wayne V]

Glow plugs use 1.5V not 3V as you mentioned, that will make for a very short life.

[Luke Planemaker]

Didn't mean to mislead anyone. I'm running the 2 glows in series, so I figured 3V would be good. Just put my multimeter in the circuit, and got 11.38V? When I first set it up, I adjusted the variable resistor in the circuit, till I got the plugs to glow. They aren't bright orange either, just red. I think it depends on how much amperage is available.
The trickle charger running the circuit is 2A-12V. Must be using the full output heating the plugs, wires, and resistor, and therefore the high voltage isn't burning the plugs. Higher amps, at that voltage, would fry the plugs, and probably the resistor also.
I realize that 1.5V is good to run a plug, as I have just been using a D cell to power the glow on my weedies, but would like to get away from that, as they are only good for a 1/2 hour, at most.
The charging system is putting out about 22VAC, but the 12V batt only shows a small voltage increase, when running. I believe the regulator took some damage when the coil cooked, probably frying a diode.
Any ideas on good way to glow these plugs, would be much appreciated. At this point, I'm thinking maybe a small transformer off the 12V lead acid, dropping the volts, to an amount useable either in series or parallel. Anyone know where to get such an animal? Or maybe a large rechargeable 1.5V battery? I want to run this engine for several hours at a time, without problems, hopefully on glow.

[Wayne V]

Well if you want the engine to run for a long time then actually use the gas/glow mix which is 1 part 10%nitro / 10% oil glow fuel mixed with 2 parts premium gasoline and then you will only need to lite the plug for starting and then the methanol in the mix will keep it going without powering the glow plug at all.

[Wayne V]

Here's some pics of my weedeater 21cc gas/glow engine, engine weight was 32oz and fit perfectly on my Lanier .40 sized "Crazy Trainer", funny thing was the CG was perfect with this engine on the nose.
Also is a pic of my friend's CAP232 with a GAS/GLOW Poulan 42cc chainsaw engine on board.

Both engines ran the gas/glow mix and used an OS 4 stroke glow plug.

[Wayne V]

One more pic....

[Flypaper]

I was going to mention the A123 batts that come in the B&D power tools as they are a little over 3 volts each and 1100 ma. 2 cells per pack. Could be wired in parallel for 2200 ma. but then I came across how long it was to run so don't know if they could cut it.

What are you towing with you plane Wayne.??

[Wayne V]

Originally Posted by Flypaper

What are you towing with you plane Wayne.??

Nothing, it just looked like a good test plane for my 21cc. One thing not to do when converting an engine is to flip the carb to make the linkage easier, what happened was the pulse line that comes from the crankcase to the carb gets cutoff so the engine will run fine on the ground but soon as it gets in the air it will die as the built in fuel pump in a walbro carb needs that pulse to pump.
So all in all my trainer made about 4 flights before i did some damage to it, i then gave it to a friend and he fixed it and used it for his 26cc Stihl gas/glow engine before putting it on his Hanger 9 Edge 540.

Here's a short clip of one of the flights http://www.rcuvideos.com/video/EXPLORER40-wmv This was before i flew at the club and is probably why landing is my strong point ( most times ).

[Luke Planemaker]

No way I could afford to run gas glow, at the rate the kohler uses fuel. Might be a different story, if I had a cheap supply of methanol, by the drum maybe.
It's running on straight gas now, but maybe it's a pipe dream to think the glow plugs would last long enough to be worth it.
Anyone know the average lifespan, in hours, of a plug? Plugs at $10 bucks a pop, would add up to a new coil pretty quick methinks.
Was mostly just experimenting for fun, to see if it would work. It kind of surprised me, that it ran smooth and idled nice, being a 4stroke gas twin, with sump.
Gord, your battery idea should work, with enough wired in parallel, but the more I look at this, I think I'll be further ahead in the long run, going back to spark.
Wayne, I notice on your poulan 21, the glow plug is quite high up in the adapter. I make my adapters so the GP is about level with the bottom of the adapter.
Did you put any taper, on your prop adapter, and does anything prevent it from spinning on the crank (other than friction from tightening), like a keyway or setscrew? Have you made a muffler system for it, or do you use the one held on by springs? I think you would see a good power increase, with a bigger carb, just looking at pic#3.
I'm surprised you could get the engine to run, with no pulse from the engine. If you tap a nipple into the crankcase, and one on the raised boss on the Walbro fuel pump, and connect them with fuel line, you can orient the carb how you like. Just make sure the carb covers the original port, or plug it off, so it doesn't suck air.
Nice deadstick BTW. I really gotta catch up on other projects, and get one of these weedies in the air. Here's a couple pics of a plug adapter, made from an old spark plug. I ground the hex part, to use a wrench on it.

[Flypaper]

Quadra Aerrow used to sell those plug adapters to use the mini Champion 1/4 in. spark and glow plugs. Think I still have a couple out in the garage somewhere. Your right about the small carbs on the weedwackers. They do that so they won't over rev. when you cut the string off on a fence.