Kripto

What are the best size/model engines to convert over to R/C gassers? Where do I find the parts to do it? I guess I could go to my local machine shop to get a prop hub made but what elese do I need to do it...

Thanks,

ChrisSpad

There's tons of info on conversions over on the giant scale engines page. I'll give you a brief rundown of what i know, though.
The three things you need to do a conversion is a prop hub, a muffler, and some sort of way to mount the engine.

Here's a link to how to build a really cheap muffler, that works great.
http://www.rcfaq.com/answers/engines/mufflerplans.htm

The engine mount is kinda one of those do what works kinda deals. Basicly, as long as its good and rigid, and won't come loose in flight, it'll work.

As far as what kind to convert, theres a bunch of them. Homelite 25cc blowers, ryobi 31 cc blowers or weedies, mccollough 32cc, homelite 33 cc, homelite 45cc, poulan 46 cc, among about a thousand aothers.
Chances are, you've got one laying around somewhere that'd work.
I picked up a 31cc ryobi weedeater engine from Ebay, for 35.00, it was complete minus the shaft, and it made a great engine. I bought a new 45cc homey chainsaw, and its a real stump puller. Gotta love swinging 20" props.
The long and short of it is to experiment, and poke around and see what you can come up with.
For 30cc size engines, i'd keep the weight to about 14 or 15 lbs max, 12 is much better. With the 46cc, i'd think you could go 20 lbs with no problems.

Kon-Tiki

You can get a Prop Hub adapter from Scott Baldrige for $15 or so!
Send him an email: [email protected]
Picture: http://www.skylites.freeserve.co.uk/...al/mvc-002.htm

Good luck with the engine . . . . my 21cc McCulloch conversion is running GREAT: http://www.skylites.freeserve.co.uk/engine-video.htm

ChrisSpad

Skylites,
Just out of curiousity, what prop and what kind of rpm are you getting out of that 21cc Mac?
Oh yeah, and whats that bad boy weigh?

I am always looking for another gasser to convert.

Kon-Tiki

No, no, no . . . it's a good boy! (bad Engines rap your knuckles for you) It weighs 2¾ lbs. I've been bench running-in and using an 18 X 6 prop. Not checked the RPM yet
http://www.skylites.freeserve.co.uk/engine-video.htm

Steve

ChrisSpad

the weights defenitely right, now, tach that bad boy (all gassers are bad boys, but, thats a good thing )
I've got a ryobi 31cc that swings an 18x6, and its a hoss.
I'll tell ya how to avoid an electric starter altogether. This is how i start my homey 45.

Take the starter rope from the conversion, and wrap it backwards 3 times around the flywheel, then pull it off. Make sure that the rope is long enough to pull off 3 turns, and still be clear of the prop when its wound up (getting your knuckles skinned with a big prop really sucks... ask me how i know). My homey 45 hits on the first pull, then starts on the second.
Its cheap, and everything you need is right there.

Aerotrend makes a small pulley that attatches to either behind, or in front of the prop that will do the same thing for a cowled installation. Its about 20.00, if memory serves, but, if its open, the rope works just as well.

Duane-RCU

My Feedback: (5)

Any plans for a giant SPAD? I have a few Ryobi and McC. to play with!

Kon-Tiki

I like the pulley idea. Would be handy to keep one in the flight box just in case the Electric Starter packs-up of the battery goes flat! Would be easy to remove the prop nut (or bolt), insert pulley in front of prop, re-fix nut . . . . and off you go.

Duane . . . YES . . . . . A Giant SPAD. Off to find some Corex (Coroplast)!

Steve in Sunny Silver End.

ChrisSpad

Duane,

There's not any plans for a giant spad that i am aware of, yet. I think there will be before too long, though. If you have built a few regular spads, you should be able to glean enough info from what others have done to build one on your own.

Kripto

Chris,

Do the conversion gassers preform as good as the high dollar Fuji's and W3's do?

Ed

ChrisSpad

well, i only own one real rc gas engine, and thats a G62 Zenoah, with the RCIgnition conversion package, which is an electronic advance ignition setup. Its a great engine, and swings a 22x10 at around 6600 rpm. Makes lots of power, and idles like a 4 stroke. The only big difference between the two that i've seen are starting and idling. The electronic ignition engines will hand prop, the conversions won't. Idle speed is also higher on the conversions with the magnetos. But, all mine will sit still on grass, and thats all i care about. The homey idles better than the ryobi, but, i've tweaked the carb on the ryobi severely for more top end, so its not a really fair comparison.
If you were to put an electronic ignition on the weedie or chainsaw conversions, i doubt you'd be able to tell the difference between the two. Most, if not all of the smaller r/c gas engines are also used for different purposes, such as chainsaws, and power equipment. The cylinder, crank and head are the same, usually the crankcase is just made a bit more accomodating for mounting, or at least thats my opinion.

Kripto

I have seen a few 4 stroke weedies at lowes the other day, Wonder how they would spin a prop. Has anyone ever tried one of them or might I be the first to try??? The cost a bit more but you never know it might make one spadass gasser....

Ed

ChrisSpad

i have a 26cc ryobi 4 stroke here. Not sure about the power output, though. Seems i was told it'd spin a 16x6 at about 6000 rpm, which ain't much, considering the weight. Not really enough for a good engine that size, but thats just my opinion. Seems that the Honda one is a bit more powerful, though.
I just looked at carr precisions website, and it spins an 18x8 at just over 6000 rpm, which is a little less than the ryobi, and i think about the same weight. That one would be good for about 12 or 13 lbs, i think.
Not sure about the ryobi. I might have to tear mine apart and just see what it'll spin.