McCoy BabyMac Question

Well, what the heck happened here? I typed out a little reply a few minutes before you posted saying I was probably going to make a backplate for this? So, now with your suggestion confirming my thoughts, I am now going to make a backarate for the tank. Thank you for your help. I wI'll keep an eye out for a WenMac needle to see if it fits.

It does, but not sure if taper sets properly (they do look pretty close) threads are the same. It looks like the backplate of tank is just a disc pressed in, a guy could even cut one out of plastic...

Ok. Similar to the other thread, the engine has been cleaned, repaired, and assembled. Now the last piece of the puzzle is to get or make a needle. Would anybody happen to know the thread pitch of a Wen-Mac or McCoy needle, so I may source out a screw in the meantime while I am searching one out? I do know for a fact that it is not 2-56, as I had already tried that. Anyways, thanks for looking and here it is. It is actually a nice looking little engine, as well, it is my first engine with a colored head! The gentleman I bought it from had 2 gaskets under the glow plug, one copper, and one steel(?). Is this a common thing, or should I remove one of them? I am also assuming a regular short plug can be used if I need one, fingers crossed I wont.

Now also, as I look at it, I would now kind of like to put it on a plane, but mounting it has me a bit confused. This is as the tank is held onto the crankcase by two bolts, and from what I read, these are to go through the firewall and mount from the backside. So, I am also assuming here that I pretty much need a profile plane with a plywood firewall, so I can access the nuts from the back of the firewall. Again, stay tuned for further progress. I am on holidays in a few weeks and then hope to get my engine test stand out from hibernation and run this thing.

Ok. With a bit more digging online, I am now believing that the threat pitch I need is a 2-64 TPI. I now have some research to do to find one. Looks like I MAY have answered my own question. Cannot find anything locally, but when I go down to Fargo this spring, I will look around there to see if one can be found.

I wouldn't hesitate to press out that spraybar and reinstall a Cox assembly. That may require opening the stock hole. Just about every engine from that time frame .15 and under used a short plug. Probably the reasoning for the double gasket was to avoid the plug hitting the piston.

Just a little update. I did make a needle from a screw I found, somehow I had just one that size. I did grind it carefully on my rotary tool, and tried it. When fully threaded in, it does seal off all airflow (blowing through fuel line on nipple side), and a few turns out it does let some flow through. The only problem is that it is just a screw that bottomed out and had no easy way to adjust the needle. So, today I soldered a piece of welding rod with a bend on teh end and a piece of fuel tubing to seal it. It appears to work good. A bit stiff to turn, but the fuel tubing will keep the 'needle' in check and not undo itself. So, until I can get a few minutes to try running it, this will be it. Heading off to the US tomorrow, and will be checking Craigslist to see if I can find anything in Grand forks, either Cox stuff, or even a parts engine for this to get the real needle.

Just as a side note. The propeller on it will not be used for running. It is just installed for the picture.

A little unexpected update. While leaving for holiday, I grabbed my engine for a joke to see if I could grab a sprae 'needle'. While cruising around town, I stopped at a Hardware Hank. Took the engine in and solved a mystery. I found the screws, err needles, I was looking for. I am glad as I now know the needle thread pitch is 1-72 tpi. As a precaution, I picked up a couple spares... I am stil, hoping that my first attempt will work fine, but, I now have a spare, and I learned the proper screw size.

On another note, I also had the same luck there finding a screw with the correct pitch for the throttle stop screworking on my MDS 40 on my air car.

NEW222 wrote:A little unexpected update.  While leaving for holiday,  I grabbed my engine for a joke to see if I could grab a sprae 'needle'. While cruising around town, I stopped at a Hardware Hank. Took the engine in and solved a mystery. I found the screws, err needles, I was looking for.  I am glad as I now know the needle thread pitch is 1-72 tpi. As a precaution,  I picked up a couple spares... I am stil, hoping that my first attempt will work fine, but, I now have a spare, and I learned the proper screw size.

On another note, I also had the same luck there finding a screw with the correct pitch for the throttle stop screworking on my MDS 40 on my air car.

Good on you Chancey!! The needle that you made will likely work just fine. Nice job on that! I like the L-bend rather than a round-knob. I'd prefer that more model-engines needles were made that way.