My 1950-1953 18" Precision Bow Saw A2T22

[K-TRON]

Yesterday, I picked up a rather complete 1950-1953 18" Precision Bow Saw, which was made in Danbury Connecticut. There is not a whole lot of information about these saws online, but I hear that the engine was built by IEL in Canada for Precision Equipment Inc. The engine is a ~3.5hp 2 cycle 1 cylinder engine of unknown bore, stroke and rpm. The saw weighs in at ~45lbs, and honestly looks like a pretty cool design. It is lightweight, seems rather safe, and you can throw it over your shoulder and carry it through the woods. It has a motorcycle style twist throttle, which adjusts fuel to the carburetor and engages a pull style clutch at the same time. I cleaned up the saw a little today and found no cracked housings or covers. The chain has a ton of life left in it, so it must not have seen too much use. The saw also has some of its original deep red factory paint on it. I am pretty excited about the saw. What drew me to it was how odd it was. I have never seen a bow saw before, and this looked like the king of them to me. Its just positively mean looking. I bet it sounded pretty good in its day and age, as the factory fitted it with a straight pipe!

I hope to fix the no spark issue, and restore this saw properly over the next few months. I have already been offered $1200 for my saw from a chainsaw collector, but it is honestly too cool to sell. I have to fix it and hear it run for myself!

For now, here is my youtube video of the saw and a few pictures,




[video=youtube;OSR4Mdw6o-M]http://www.youtube.com/watch?v=OSR4Mdw6o-M[/video]


Christopher Kouttron

 

[K-TRON]

I finally got around to working on my Precision saw.
I started out by carefully removing the flywheel retaining nut. I took my best judgement and decided that based on the cut of the thread that it was a standard righty-tighty, lefty-loosy nut. With a 1" socket and a 1/2" ratchet it came off pretty easily. I removed the three 1/4"-20 bolts which retained the starter cup and then figured out how to remove the flywheel without damaging it. I decided that I would use three 3" 1/4'-20 stainless bolts, a large bolt to fill the hole, and the starter cup as a puller. Because parts are absolutely non-existent. I literally turned each bolt 1/4 turn and checked for deflection in the starter cup. After a few minutes of painstakingly slow turning, the flywheel popped off its taper completely unharmed!



Chris

 

[K-TRON]

The flywheel is made by WICO, part number Y6132. I found it odd that the flywheel had its part number sharpie'd to the side of it. After a little cleaning it really looks like new. The magnets are strong, and none of the surfaces are worn. I wonder if the flywheel had been replaced just before it was stored away for all of these years??? I know that someone has been in here as the kill switch is cut and electrical taped, and the three starter cup retaining bolts had different style lock washers. Anyhow, it uses a WICO coil, part number X7560. The points have a bakelite armature, and honestly the points are pretty clean and square. Usually they are rounded and corroded. The reason why it had no spark was that the armature on the points was not even touching the pressed on lobe on the crankshaft. After I file the points, clean the lubricating wick, and polish the points lobe, I bet it will have spark! Everything looks remarkably clean in there. You can even see the nice red paint under neath the 3/16" to 1/4" thick sludge buildup in the blower housing.



Chris

 

[K-TRON]

Yesterday I spent a few hours cleaning the inside of the blower shroud, cleaning the lobe which drives the points, filing the points, and making sure everything was nice and clean, lubricated and adjusted. When I put the saw back together and pulled the rope I had spark but it was weak. Oddly enough on the second pull the spark went away. This morning when I went back out to work on the saw, I checked the plug. It was wet, but what I noticed was that the ground electrode must have hit the piston and was shorting on the main center electrode. I re-gapped at 0.025", and made my own 1/16" thick fire ring for it out of a washer. I threaded the plug and washer in place, pulled the cord and the engine coughed. I decided to film the startup procedure and just uploaded it to youtube for you guys to watch. It took a bit to get going, but it does run pretty good, despite the fact that the carburetor has not been gone through yet!

[video=youtube;Y8P_6K62NoE]http://www.youtube.com/watch?feature=player_embedded&v=Y8P_6K62NoE[/video]


The tag says:
"Mix THOROUGHLY one quart MACMILLAN RING-FREE MOTOR OIL with 2-1/2 gallons good grade regular gasoline. FIRST TWO WEEKS of operation use one quart to 2 gallons and then shift to above mixture."

That would mean, a 10:1 ratio, and a 8:1 break in oil mix!!!
With the way that unburnt oil is gathering in the exhaust manifold, I would think 16:1 is already too rich of a mixture!
The cylinder has been sitting in PBlaster for as long as it has been with me. It does smoke a lot, but it will all clear up when the carburetor is rebuilt and I put the proper mix fuel in the engine.

Chris

 

[K-TRON]

As you can see in the video, the saw does not run very good.
I have not gone through the carburetor yet, but that is on the TO DO list.

The carburetor is a Tillotson MD10A




Chris

 

[K-TRON]

Does anyone know where I might be able to find a new old stock gasket kit for this Tillotson MD carburetor?
- I am going to try "Discount Marine Parts" 1-906-466-2180 as they advertise on ebay.
- I have never dealt with them, and am always open to suggestions on where to go for X and Y.

Does anyone know what the original plug in this saw would be?
- The champion plug it has has too long of a reach. I had to make a fire ring for it to prevent piston slap.

Lastly, does anyone know if this saw should have had a recoil starter on it? Does anyone have a picture of a Precision with a recoil?
- Based on the 5 threaded holes in the blower housing, I would say that the recoil is missing


Thanks,
Chris

 

[Bob95065]

You should talk to Joe Salva of Sugar Creek Supply. He recreates NLA carb kits for a reasonable price. He also recreates chainsaw decal sets.

You can visit his store on another forum here: ###################################/phpbb3/viewforum.php?f=104.

Joe has a day job and makes saw parts on weekends. He is a really nice guy and very easy to work with. If he doesn't have parts for your carb he may want to add a carb kit for that model to his inventory.

Bob

 

[cbfarmall]

I got a couple Tilly AJ kits for my Disstons from Discount Marine. Not super cheap, but the kits came with packing for the high speed needle, a new needle and seat assembly, and a few other parts. It's a good company to deal with.

If I recall, an MD gasket isn't real hard to duplicate at home.

Chris B.