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Building Tips and technical articles. => 1/2 A building. => Topic started by: Larry Renger on October 18, 2012, 11:50:45 PM
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A few of the Man-Cave crew aren't happy with their Black Widows' performance, so I bought 6 sets of parts to upgrade them as close to Venom status as I can. I got Killer Cranks, TD cylinder/pistons, and the washers that go between case and drive washer to prevent galling when using a power starter.
Tonight, I polished the Killer Cranks by threading them onto a 5x40 length of threaded rod, chucking them into a drill press at low speed, and wrapping oil soaked 800 grit around, and letting it run for about 30 seconds. Visible improvement in the finish! I took it easy, but may go to 2000 grit for final fitting.
Note, you do NOT lap a crank into the case, the case is anodized, relatively soft Aluminum, and you ONLY want to work on the crankshaft to achieve a good fit! Only the anodizing provides a hard surface to withstand hard use; cut through that and you are doomed to short life.
Next up will be dis-assembling the engines and cleaning all the parts. The fit of shaft to case is a major component of performance, so there may be some mix and match and re-fitting going on.
Sadly, the pistons and cylinders are not taper ground, nor tight enough to fake it. :'(
More as it happens. :D
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Will you chrome the piston/cylinders to get a good fit?
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Will you chrome the piston/cylinders to get a good fit?
Thread hi jack, sorta!
Where can someone get sleeves/pistons chromed these days?
BIG Bear
RNMM/AMM
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the answer is no, because I wouldn't mind knowing where to get that done myself! ;D
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Where do you get the Killer Cranks? Are they still available? Can you post pictures of your setup?
Thanks
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Hello Jay, here's the link http://coxengines.ca/cox-.049-killer-bee-diesel-crank.html . Ken
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The cranks look good, and not all the spendy. Do they make a left-handed model for carrier?
Until I can get some healthy cylinders I won't have enough power to break a crank.
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Paul,
Reedys will run either direction. There is no timing in the crank. The experts can clarify this.
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They do? Mine always start backwards. I've invested fortune in pusher props.
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Spring starters help solve the backward starting. But, I 've watched Bill Lee start his reed engines with a backward flip and getting one flip starts.
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gentle back flip often results in easy one flip start assuming the engine is already tuned. I usually put my finger near the hub and backflip letting my finger slip out as I feel the engine fire. since I am back flipping the resulting "backfire" almost always results in a forward running engine.
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Just something to add to the equation. Wayne, I start my engines just like your suggesting. This does work but sometimes, you get that stubborn bugger. Also, over priming will result in the forward to backward run. When one does run backwards, I used to just grab the spinner with my fingers and squeeze to stop it. I'm well aware that from a safety feature this can result in something bad. What I didn't expect is what happened to my engines. I quickly ditched the cam starters for the simple fact that I felt they were robbing power. Most if not all of my Cox traditional springs had hitch hiked a ride with the propeller bending them all up. It wasn't until afterwards I realized the benefit of the hex drive cam which prevents backward runs. I'm still not a fan of them especially due to the fact it falls off when one doesn't have a prop bolted on.
Reason I feel this is important is that later on after cutting my fingers several times, I learned an important lesson about sanding props and wearing a starter glove. This now enabled me to be quite aggressive with the spinner when it did run backwards. The constant grabbing of the spinner actually wore out some of the crank fits to the case. Holding the spinner would really vibrate the engine. This was readily apparent in my Black Widow engines as I could see the anodizing inside the bore with crazy wear marks. I had a horrendous amount of side to side play which would vibrate so badly it would kill off several thousand rpm's.
As Larry Renger stated, once the anodizing is worn out the case isn't far behind. I also contribute this to the fact that certain anodizing process's are harder than the aluminum itself. I had read prior that my practice of stopping the engine indeed will do exactly as I just described.
Lessons learned and the proper way is to place your thumb and forefinger over the fill and overflow vents and indeed the engine will stop.
Crankcases can be purchased rather inexpensively nowadays, but I don't see the need to ruin one due to my experience. Ken
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They do? Mine always start backwards. I've invested fortune in pusher props.
Paul, in my experience reedies tend to start the opposite direction from how you flip them. Unless, of course, you flip them backwards...