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SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

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Old 10-17-2010, 07:38 PM
  #476
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

That is some good work. Now you can run normal oil ratios?
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Old 10-17-2010, 08:51 PM
  #477
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

W8YE,
Can I run normal oil ratios? That's a great question. Originally, the intent was to simply have the rod SURVIVE at "normal" oil ratios. Normal is a range, of course, and is subject to a lot of opinion. I would say normal is around 32:1 or there-a-bouts. Some would say higher, and there are oils that go to 50:1 and more. I really don't want this thread to run 6 pages of oil opinions though.

Having said all that, it still is a great question. The events surrounding my engine development caused me to remove the rod and replacing it with the stock one. I ran into severe resonances, thinking it was the greater mass of the rod/bearing combo. So I removed the rod. I was chasing ghosts, though. The resonance turned out to be a perfect storm of peaks in the engine test stand. Most don't realize the damping characteristics of an airframe that allows single cylinder engines to run at all.

Once I discovered the stock rod can survive, I never put the needle bearing back in the engine. Had I done so, the investigation obviously would have turn to "leaning" the oil mixture to get more power. I speculate now it might be a wash between leaner oil mixture and the increased mass of the rod/bearing. However, there would be less friction though. Heck, it would be a great new direction to take this. Maybe maybe. But that engine is SOVERYHAPPY in the Hangar 9 Stearman now, wowing every engine nerd who sees it and HAPPENS to notice I don't use a glo starter at the field.
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Old 10-17-2010, 09:18 PM
  #478
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Personally I am a 32:1 mineral oil guy.

Good discussion about all the factors involved
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Old 10-18-2010, 03:10 PM
  #479
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Recently I converted my OS Ft 160 twin and my OS ft 300 twin to spark ignition. They both run smooth at idle and top end but tend to load up in the midrange. The plugs foul and the engines run terrible after that. On the Rimfire vr2 spark plugs the problem is not so bad and will clear with full throttle. On the chinese plugs they will stumble and run poorly until cleaned. Th Rimfire vr2 plugs came gapped at about .018 in. The chinese plugs seem to run best about the same. I am running 10%nitro /18% oil Coolpower for fuel and the timing is set for 28 btdc. Are there better gaps to try? Maybe the Mixture is set wrong ? Both idle at 1500 rpm. The 160 top end is 6400 with a zinger 18/6-10. The 300 top end is 6400 with a 20/10 zinger. They both are low time engines. Less than 1/2 gal bench time.only.
Any advice would be appreciated.
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Old 10-18-2010, 03:49 PM
  #480
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Cut the oil to 10-12%.
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Old 10-29-2010, 09:53 PM
  #481
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Hello, Have seen reference to the Walbro wt456-1 as a good 4-stroke 2-needle carb. Have a Honda GX31 & was wondering if this would be a good replacement for the stock carb? Also the phenolic mount is HUGE in thickness - any ideas where to get a thinner one. Additionally have a FA270T hoping to convert to EI using 20:1 gas\oil. If not satisfied with results of stock carb, would this same Walbro wt 456-1 be a viable option? Last question (for this post) would a rare earth magnet (like sold at Radio Shack) be the correct type of magnet to use with the Hall sensor pickup? Do appreciate all the great info these forums provide & extra thanx to w8ye for the many pm's Many Thanx T-man49
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Old 10-29-2010, 10:12 PM
  #482
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

CH Ignition's magnet was a rare earth 1/8" dia and some were only 1/8" long

Radio Shack used to sell the perfect magnet but any more I don't see anything but flat magnets on the site?
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Old 10-29-2010, 10:15 PM
  #483
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

The Walbro WT-456 should be a good alternative for you and you only need to use the intake manifold for your pulse signal.

The Walbro WT-456 sould also work well on the GX-31


Changing subject . . . .
Some of the Walbro rotary valve carbs have a low speed needle inside the throttle arm like a glow engine carb.
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Old 10-29-2010, 10:22 PM
  #484
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Here's link to a nice Neodymium magnet that is the size of the CH magnets

http://www.kjmagnetics.com/proddetail.asp?prod=D22-N52
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Old 10-30-2010, 02:24 AM
  #485
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Yes, those are good, I did not know that CH use them. This is the same source and magnets that I use.

I hope that today I will test fly the saito FG 20 with Walbro 456-1, I had to buy a PT 17 for it.

Adrian
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Old 10-30-2010, 08:10 AM
  #486
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION


Quote:
ORIGINAL: triumphman49

Hello, Have seen reference to the Walbro wt456-1 as a good 4-stroke 2-needle carb. Have a Honda GX31 & was wondering if this would be a good replacement for the stock carb? Also the phenolic mount is HUGE in thickness - any ideas where to get a thinner one. Additionally have a FA270T hoping to convert to EI using 20:1 gas\oil. If not satisfied with results of stock carb, would this same Walbro wt 456-1 be a viable option? Last question (for this post) would a rare earth magnet (like sold at Radio Shack) be the correct type of magnet to use with the Hall sensor pickup? Do appreciate all the great info these forums provide & extra thanx to w8ye for the many pm's Many Thanx T-man49
Regarding the FA270T conversion, since you mentioned using the stock carb, I assume you're sticking with glo fuel then? The stock carb won't work with gasoline well at all. What's the 20:1 then?

Some people like to just put EI on their glo fuel engines. I never really understood the attraction, unless it's low reliable idle. But a well running glo engine can idle fine anyway. I'm not really sure of the point of doing this type of conversion. Maybe you're not, and I just misunderstood your post.

Gasoline is cheaper, and cleaner. Yes, the power output lower despite it's higher heat content. So one would be wise to use a slightly bigger engine than would otherwise be necessary. Also, upsize the engine because you're now carrying the extra weight of a module and 2nd battery. All this means one should watch the wing loading and be careful of airplane choice. I once, unwisely, put a weedie EI conversion in a Super Star aerobatic plane. The plane was about 2lbs overweight. The wing loading approached 35 oz /ft2. I was doing a loop and the plane suffered an accelerated stall on the downside of the loop. The plane simple fell out of the sky. This was a dumb thing to do, so choose your plane carefully. Gas conversions are fun, but they must make sense. Nothing delivers the power of a lightweight 2 stroke. Despite all this, gas conversions are my first choice. Just don't do a conversion and make the mistake of pushing for RPMs as your measure of performance. Load the engine down with a bigger prop and use the torque they are best at delivering.

OK, this post got a bit preachy and opinionated. Itll probably set off a whole new set of arguments. But I don't feel like rewriting it, so here goes. )
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Old 10-30-2010, 09:02 AM
  #487
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Hi Pull Up, Guess I just have a hankerin for a big 4-stroke twin on gas. Don't expect to set the world on fire, matter of fact, have a big Sig Spacewalker that hope will fly fine with it. Your post does mirror much info garnered from these forums & do respect your willingness to share. Seems some have had sucess in utilizing stock glow carb for gas, guess we'll see if I'll be one of them. By the way, also have a 10cc Webra, old but still NIB, that is set up with ignition & instructions indicate usage of either gas or glow thru stock carb. Not sure yet, but considering a Kitfox Classic IV (.40 4-stroke size) w\80" ws for it. Hey, Thanx again & have a great day T-man49
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Old 10-30-2010, 09:29 AM
  #488
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Running methanol with spark is great. The engine designed for methanol doesn't have any trouble with the carb or cooling. They start easy and with spark run much leaner so you still save fuel. The power loss going to no nitro is small. If you can easily get no nitro fuel or methanol and mix your own it's just as convenient as getting a gallon of gasoline.
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Old 10-30-2010, 09:33 AM
  #489
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

I have a Saito 150 on gas with the original carb. It runs pretty good. It is not too different from the way my Saito FG-20 and FG-36 engines run.
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Old 10-30-2010, 09:43 AM
  #490
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

OK, T-man, that solves the mystery...you're going to use gasoline on the Twin.

It will be interesting to see how that Webra runs with the carb for both gas and nitro. Usually, the nitro carb is not sensitive enough for gas. The reason is nito fuel carries some of it's oxidizer already in the chemistry. Gasoline gets all it's oxidizer from the air, making it's mixture more critical.

On the Twin, the WT456 will also be interesting. The venturi is only 6.5mm. That seems well balanced for an engine with about 20-25cc displacement. So, looking at both ends of the spectrum, you could have too little engine for the carb, OR too little carb for the engine. Your twin would be the latter. Of the two, I'm SPECULATINGthat the former would be the least pleasing as you'd get no idle and a crappy transition. The latter condition (your situation) would just make you suffer a little on the high end performance. Keep in mind this is just speculation based on the physics involved.

Another option is to get a WT carb with a bigger venturi and adapt the pump cover and pump return assist spring to it. I'd guess you need around 8 or 9 mm venturi to get in the right range. I always try the path of least work first, so try the stock WT456 carb first. Also, another difference with the WT456 is it has a really cool accelerator pump that is relatively rare on Walbros. Your larger replacement carb wouldn't have that PROBABLY. It would be an exhaustive search through wem.walbro.com because their search engine is old than dirt. Once you're done, just don't do any ENGINE mods to compensate for the carb holding back performance. And the one thing I wouldn't do is use the stock nitro carb with gasoline. You'll be disappointed.
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Old 10-30-2010, 10:07 AM
  #491
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Thanks for your comments. At this point, it might be illuminating to say what your methanol mix is.

The fact you have to say "if" you can get no-nitro fuel easily is evidence for most it's not convenient. And then there's the cost factor. You have castor oil or synthetic in the methanol? If so, it's that oil that a lot of people don't like to clean up. For most people who aren't in the exotic gas or mineral oil crowd, the choice is nitro or ethanol from the gas station. By the way, interestingly enough, on a Saito 150 gas conversion I did for a friend, it ran really poorly on no-ethanol gasoline. We all thought that would be better, but it overheated the engine. The cooling effects of the alcohol and the resulting reliability was well worth any performance loss.

You hit on the one advantage to glo-EI that I overlooked. They start easily. That is really true. The modeller will have to decide if that's worth the weight gain.

Quote:
ORIGINAL: gkamysz

Running methanol with spark is great. The engine designed for methanol doesn't have any trouble with the carb or cooling. They start easy and with spark run much leaner so you still save fuel. The power loss going to no nitro is small. If you can easily get no nitro fuel or methanol and mix your own it's just as convenient as getting a gallon of gasoline.
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Old 10-30-2010, 11:02 AM
  #492
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Hey Pull Up, Options, options, options....luv em, & following the path of least WORK I can certainly appreciate and always try for. Kidding aside, as an alternate firing twin, each cylinder seems to fall rite in the capacity you've referenced for the wt 456-1. GKamysz, would guess the same 5:1 oil ratio would be necessary with methanol fuel? w8ye, think your suggesting I check carb on the Honda for a low speed adjustment as it may already be a 2-needle carb? Any way it flows, don't expect to be disappointed with the big twin, even if it goes back to glow fuel Thanx again for all the info T-man49
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Old 10-30-2010, 11:04 AM
  #493
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Dumb question but I will ask anyway, is there any benifit to run a gas boat engine with nitro mixed in the gas??? I have heard most saying run on 87, or coleman lantern fuel, how can the fuel be hopped up.

Richard
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Old 10-30-2010, 11:22 AM
  #494
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Hi all, one other question, What would be a good starting prop size for the FA270T conversion? 20" .... 22"? T-man49
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Old 10-30-2010, 11:30 AM
  #495
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

I run less than 18% oil. As low as 8%, but I think 10-12% is safe. Cleaning an airplane is not a big deal. If you haven't flown a diesel, you've not dealt with a messy airplane.
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Old 10-30-2010, 01:28 PM
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Another subject: Aluminum propellers
I have a big LongEZ with the engine in the rear. Flies weird. I belong to a club with a grass field, and it flies fine there without rocks kicking up and ruining the prop. But my OTHER field, near my work for lunchtime flying, has some gravel patches that wreak havoc. Has anyone heard of functional aluminum props ever being made, or tried, for RC usage?
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Old 10-30-2010, 04:55 PM
  #497
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

None exist. AMA bylaws make them illegal. I don't think any manufacturer wants to touch that anyhow.
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Old 10-30-2010, 06:30 PM
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Ok, Today I put in a air the PT 17 with the modified FG 20 with WT 456-1 carb. This is also first time when I test it inverted. Up in air it performed the same like on the stand.
Fast response and run rock solid.
I used 20:1 evolution oil (recomanded by HH.) with 98 Shell gasoline ( not solty...BP)
APC 16.5 x 5W at 8200 Rpm's, Plane weights 14.5 wet. I measure the thrust with a digital scale and at WOT I got 10.7-8 LB thrust.
Tomorrow if it is not windy will fly again and try to make a video.

Thank You
Adrian
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Old 10-30-2010, 08:31 PM
  #499
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Adrian, Thanks for the report
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Old 11-01-2010, 03:06 AM
  #500
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Default RE: SMALL DISPLACEMENT FOUR STROKE GLOW TO GAS CONVERSION

Very nice thread!
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