wen mac mkXIII video

chevyiron420 wrote:This is the first video I have ever attempted. Yesterday I got 14500 rpm out of it but not today. I think its leaking air around the needle valve. I do have the original cylinder back on, and found a piston\rod with a pretty good fit. Its running on 10%-26% fuel and a 6x3 cox prop.
https://www.youtube.com/watch?v=OcCFEhqDWSI

roddie wrote:Hey Phil! Congrats on your first video man!! I'd never heard a Wen-Mac run before. She seemed to run pretty steady. Actually makes me want to run my recent rebuild. My needles for the rotary-valve engines all have "flex-cable" extensions.. and both needles seem "loose".. like they'd likely leak air. I only have two of those needles.. and one is noticeably bent.

Do you have any "Dubro" small (1/2A size) silicone fuel tubing.. or "any" silicone fuel-tubing small enough to fit snugly over the threads of the needle? If you suspect an air-leak there.. that would likely fix it. That's a place to start anyway. Is 14.5K what you're used to seeing on that fuel blend and prop?

You had previously mentioned to me, that the heavy starter/flywheel assy. on these engines can be removed.. and a Cox drive-plate fitted to significantly reduce weight. That starter-flywheel weighs nearly .25oz. and the band-spring (which would be discarded) would definitely put the assy. over .25oz. The Wen-Mac/Testors .049 engines have a 6-32 threaded crankshaft.. correct? This would entail enlarging (drilling-out) the Cox .049's drive-plate.. right? Do you know which size drill would be used.. to best enable the crankshaft's splines to be cut into a Cox drive-plate? It would seem a worthwhile mod to make for a lighter-weight engine. These engines probably don't make near the power of a Cox Medallion.. but they don't suffer from the gremlins of reed-valve induction either. It would be interesting to "strip one down" and build a small model such as a Goldberg "Stuntman 23" or a Sig "Skyray".. to see how it performs.

chevyiron420 wrote:roddie, yep that was a car engine. I think the drill bit size for drilling the cox drive washer is a #13  .185, you might start with a #14 and see if it will start on your shaft first.
Now, the spring housing is not pressed on, its just held on with two little rivets. They look like tiny nails with spiral splines. All you do is get a small screw driver under the housing and wiggle and pry till the rivets start to back out. If you bend the housing a little lay it flat on something substantial like a vise and put a piece of round stock in it, or a upside down socket and tap it back in shape. The late model wen macs and the testors have the rivets horizontal. The wen macs are marked with a little bar under the 049. The early engines have the vertical rivets. If you remove the starter from one with the rivet in the carb, plug the hole or you wont be able to choke the engine.
Have you got your testors mccoy together? I would love to see a video of it running. I bet it will out run my wen mac mkXIII.