stunthanger.com
Engine basics => Engine set up tips => Topic started by: Paul Allen on April 03, 2013, 02:45:27 AM
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Guy's
Can anyone shed some light on the engine in the photo, is it usable
as a stunt motor?
thanks
Paul
In OZ
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I've flown the 4011, a later model, on several airplanes and really like it. Try an APC 11 x 5 as a starting point.
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I made a slight modification to one - I radiused the combustion chamber out to .45, leaving a .04 squish band.
Also, I used an ENYA NVA and removed all the paper gaskets.
Although a bit thirsty, it ran and sounded like a Fox 35 on steroids!
Nice engine and very smooth.
Bob Z.
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Many moons ago I used those in FF models and they turned a 11x4 at 18,000+. Had it in a Starduster 900
Ed
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I made a slight modification to one - I radiused the combustion chamber out to .45, leaving a .04 squish band.
Also, I used an ENYA NVA and removed all the paper gaskets.
Although a bit thirsty, it ran and sounded like a Fox 35 on steroids!
Nice engine and very smooth.
Bob Z.
That cast head version (early production) had a wedge head. The barstock heads were hemi/squishband design. The cranks tend to snap at the front bearing, the aluminum ring around the crank disc sometimes came loose, as did the pressed-in crankpins. The Dykes rings worked great, until they didn't work right anymore, and the plastic wristpin pads were not real durable. The later front end (#4050 & 4055 series) was much more durable and a lot heavier, putting it up to about 10.5 oz. In short, I would not bother with it, but if you want to use it in a plane where you can easily swap in something else, it could be fun. The Starduster 900 would be a good choice! H^^ Steve
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Steve
Yes, the head is a wedge type, no gaskets used in this engine, its new
never been run, so I will keep it for display. Why did it have the ring around the crankshaft?
Thanks
Paul
In OZ
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Paul, the aluminum ring on the crank is for crankcase "stuffing". The idea is to provide better "pumping action", but in fact it doesn't do anything, and is sometimes a source of grief. I never had that problem, but had all the others...in spades. What happened was that after a typical combat match crash (with the .35 version), the crank would soon snap, there would be a spectacular shaft-run, the crankpin would come out of the crank a bit, grind up the backplate, and eat the piston/cylinder. The factory was really quite good about fixing the broken stuff, but it was a hassle to be wondering when you'd get your engine back, and then have to break-in again. Besides, fuel was around $4/gallon, ya know?! H^^ Steve
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Some have ' P ' stamped on the front of the ( wedge 0 head , for Pylon . . . .
The rat Racer GRMZYPH used these things .
Had one in a 57 Oz 57 in. aerobatic model , dark red . Scarlet Even .
Flying it at dusk it was a notch lean . Wound needle in , 1 7/8 turns.
Right . Set it to Two . Except somehow it was one . . .
11x 5 master or zinger was good .
Sounds like you need to build a Rat Racer for it though . %^@ H^^
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I've just aquired a K@B Torpedo 29, (it's soaking in paraffin at the minute!). This is a really old motor from the 50's I think. - Would I have to use a sloppy rich fuel mix as with my Foxes?
They like alot of nitro don't they; 25%+.
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is it a 3 bolt or 4 bolt backplate if 4 bolt dose it have a silver or green head the silver head ( 29R ) was a racing engine ,the green head (29S ) was not one of their more powerful engines
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The motors a 3 bolt with a green head. Turns out the liner was fitted the wrong way round (transfer port higher than exhaust port). I sorted this out, but it will only just run due to next to no compression! - Do you know if any piston for a 29 will work or would I be best to have one made? (Bore size is 0.724")
Any ideas would be appreciated,
Tim
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Clean the piston up good with lacquer thinner, heat it up with a butane torch until starting to turn red, and drop it in a can of motor oil. Have plenty of oil in the can and do it outside. It will smoke a bit. That may grow the piston enough to get compression back. It has worked for me. To heat the piston I put a piece of music wire in a vice and put the piston on top of the wire. Try to heat it as evenly as you can.