OK I had a friend of mine give me an old Craftsman Chainsaw to convert, but I am having a little trouble identifying the engine. I read a bunch of posts saying that alot of Craftsman saws used Poulan engines, but this doesn't seem to be a poulan. The cylinder head itself is quite large with an apporx. bore size of 1.90". The bottom half of the engine is part of the saw case itself, kinda of like a Sachs engine. The carb is Walbro but a bit larger than your average run of the mill walbro carb. When I set this engine beside my Homelite 45cc conversion it seems quite a bit larger. The only identifying mark I can find on the cylinder so far is a star with 2 lines through it. Well what do you think ? What is it ? I can try and post some pics in the next day or so.

Thanks in Advance
Scott

Which model craftsman saw? Is the sears model tag still on it? The first three numbers of sears/craftsman model numbers denotes the vendor. I.E. 143-....... is Tecumseh, etc. I can find out tomorrow(monday) if you can post a model number, or carb numbers.

Just an aside; not too long ago in this area a guy attacked his brother with a chainsaw while drunk. The story was on the news, complete with pictures of the saw. It was an oooolllddd craftsman. Next day at work I asked one of my co workers if he had seen it. he had and we both laughed that the guy must have been REALLY mad if he got that old thing started.

Im converting an old craftsman saw that is like yours. Mine ia a 3.0ci or 48cc. I had to cut it away from the crankcase too. My model number is 358.356070 If you can find your model # check here http://www3.sears.com/

The model number is worn off the sticker, is there any other place it might be stamped on the saw ? The carb is a Walbro HDB-8C, which I can't seem to get to cross to any specific model.

Scott

Ok I came up with the model number for the saw 358.356091, see if that will help.

Scott

I am pretty sure the 358 prefix is Poulan as the vendor to Sears, but I might be wrong in that quickie asessment. Lemme run the rest of the number tomorrow, and I will have details for you.

The hbd-8c is a partial. There should be a couple other numbers stamped(rather than cast) into a flat spot on the carb(various locations). Those are the spec numbers denoting jet and passage sizes, which narrow the application info down.

you've got a large poulan saw like I do but I cant tell how big. The sears site gives only the parts numbers for your saw and no size info. I can tell you that its at least a 48cc or bigger. Thats the piont where all the larger saws had the crank built into the saw case and you have to cut it out on a band saw. Heck, you might have a 50cc-52cc, or even up into the 60's. hard to say. if you can guage the bore and stroke, that will tell you. Piper

wow!...its a big'n...umm, you dont want to convert it....nope...maybe you should sell it to me, (wink-wink). man find out how big that thing is. just by looking at the parts list and pics of all its parts its built to cut some big wood. I'll post some pics of mine this week so you can see what it should look like cut out of the case and ready to fly. Piper

That model number comes up as a Poulan/Baird 3.7 cubic inch engine. 6.13c.u. is 100cc-you can do the math, but am getting 60 or so cc's.

My boss says they were quite smooth in their day, but a heavy saw to lug around.

Have fun with it.

Thanks for the information, I am getting 60cc also. Looks like it might be a worthy conversion. I just have to figure out how to cut it down and if I want to try and keep the mag ignition or not. I was looking over the case and trying to figure out a good way to mount the engine once the case is trimmed, anyone got any good ideas on mounts for this style engine ?

Scott

hey superfast, How I intend to mount mine is like the Fuji style. On the back of the engine use a plate mount. By using longer case bolts you can bolt through the plate and the case. Heres a pic of how to do it on a homelite motor but it applies to our saw motors too.

Mr. Pipercub has the right idea. I don't have a bunch of experience putting converted saw engines in r/c planes but in kart/scooter/bicycle kicker conversions, that is how it is done. There should be a blank boss or two on the cylinder that could be drilled and tapped for use as a headstay to keep vibration down a bit. That engine might/should have a spot for a compression release as well.

I think it would be very cool/interesting to use a saw engine's oiler(or oiler drive) as an hydraulic pump for retracts. Or for a smoke trail setup.

I've done a Craftsman 54cc engine. Actually, it's from a Poulan Pro 335 chainsaw------same exact saw. I have a Craftsman 3.0 saw with 20" blade and the Poulan Pro 335------both the exact same saw.

Cut it apart with a portable bandsaw. Then finish it up with a grinder. Cut everything that's not needed to keep it together.

Get rid of the magneto. It weighs a ton and you can get an electronic ignition for it for about $150. Well worth it.

After you get it apart, you will need to cut the clutch and sprocket off the crankshaft. Remove the jug and then split the case apart. You need to remove the magneto and the clutch to split the case. The magneto is easy; just remove the bolt on the front and pry it off with a prybar or big screwdriver. The clutch is easy too. Just stick a big screwdriver in the clutch and smack it with a hammer. It spins right off.

When you have the mag and clutch removed; then you can unbolt the jug(cylinder) and split the case. Take all the bolts out and use a putty knife to break the gasket seal. Remove the crankshaft and chuck it up in a vice with a towel or soft cloth wrapped around it to keep from damageing it. NOW, you can cut the crankshaft off with a bandsaw. Don't try to cut the crank off when it's still in the case. The heat from cutting will ruin the seal on the bearing.

After you cut the crank off, you can reassemble the engine. Put the crank back in BACKWARDS. And then flip your cylinder 180 degrees to match it. The reason for this is to give yourself a bracket mount for the ignition system. One the clutch side of the case, there was an automatic oiler for the bar. Use the two bolt holes for the oiler to attatch your timing bracket. The case is the same on both sides-- except for the two bolt holes from the oiler. Flipping everything around backwards is no problem. You may have to take a Dremel to the case to help the transfer ports between the cylinder and case to match up perfectly, but it's pretty close anyway. I did not dremel my ports. Engine runs great.

Okay, so you got the shaft cut off and you've flipped everything and reassembled the engine at this point. You need an aluminum adaptor to attatch the carb and you need a phenolic(sp?) spacer to insulate the carb. My carb is a Walbro HDA------same as a G-38. So, I bought a phenolic spacer for a G-38---$12.00 Maybe you can reference your carb to another popular RC engine and buy that spacer.

You also need an electronic ignition and a timing bracket. CH or Ralph Cunningham for the ignition.

The timing bracket is just a U shaped bracket with two oblong slots in it. This will hold your Hall sensor. The slotted bolt holes make it adjustable-- for setting your timing. Bolt it to the two holes in the front of the case--where the oiler used to bolt up.

The carb adaptor will have to be tapped and threaded into the side of the cylinder. Use 4 bolts--8/32 X 3/4" Put the adaptor on as a dry fit and then drill and tap for the bolts. Take the adaptor off and then make a gasket from 1/16" thick gasket material-available at all auto parts stores--Use COPPER RTV liquid gasket maker(also available from the auto parts store) and apply it to both sides of the gasket, and to the cylinder face. Put the gasket on and the SQUEEZE!!! the adaptor back on for a very tight fit. Then run your bolts in and wait for it to dry. Don't tap the holes with the gasket in. Tap the holes with no gasket first and then when you install the gasket, it will take up enough space to make it a tight fit when installing the bolts. This keeps the carb from leaking air.

On the backplate- others have already given great suggestions about how to mount it. Run your case bolts all the way through-- front to back-- and use a nylon lock nut to bolt the backplate mount right to the case.

The magneto:
Send it to Ken Lambert. He will machine the magneto down to the size of a quarter(25c). And he will install a magnet for you. He can also make a prop hub for you. When it's done, the magneto will be about 1" in diameter and have a magnet(crank trigger) in the side for your ignition. It will have the magnet in the right spot for your timing; and it only goes on the crankshaft one way-- you can't screw it up. The prop hub will screw onto the threads over the mangeto. This locks the magneto(crank trigger) on and gives a good solid hub for the prop.

Long winded; sorry.

Here are some better pics of the engine after it's done.

You can see the phenolic spacer.
You can see the carb adaptor and where I had to drill a hole in the fins to install one of the bolts into the cylinder.
There is whats left of the magneto and the magnet(crank trigger) that installed into the side of it.

Muffler is a Bisson for an upright mounted Moki180-210. The Moki has a 34mm bolt spacing and the Poulan has 36mm spacing. I just drilled the holes out bigger and it bolted right up. Sounds nice.

I'm using an insulator on my pulse line from the case to the carb. I wanted to insulate the line to keep the exhaust from melting the line.

Ken Lambert made my carb adaptor, timing bracket, backplate mount, prop hub, and he turned my magneto down on a lathe and installed the magnet. It all works.

These are the pics of the engine when it was removed from the saw. I hadn't cut it up yet.

You can see on the first pic; this is the side where the clutch and sprocket where. Mainly- notice the two bolt holes on the left and right sides of the crank. Those are the holes I used to mount my U shaped timing bracket.

But, in this pic-- thats the wrong side of the motor. You'll cut that side of the crank off and then flip the motor around backwards in the case. Don't forget the flip the cylinder to match.

In the second pic, you are looking at the side where the magneto was attatched. This is the side where the crank is tapered and has a keyway. This is the front of the motor at this point; before I flipped it around. The big giant hole on the left side is where the bar oil was filled. Two small holes - just slightly to the right and up-- are where the coil was mounted for the magneto.

Third pic. Back of the engine. You can see the intake port, plug hole, and the pulse line. After flipping the engine, the pulse line and intake port will be on oppostie sides from each other. You'll need a longer hose, and possibly some kind of insulation on the line to keep it from begin melted as it passes by the exhaust.

4th pic-- after a little cutting. Not done yet.

Best thing about this engine?

I've got $300 in it. Thats for everything; muffler, ignition, machine work fron Ken,-----everything.

It weighs about 4lbs, 13oz. RTF with the battery, switch, ign, muffler and prop. A little heavy, but not unreasonable.

It turns a 22-8 at 6800-6900RPM with Husky oil/unleaded gas at 40:1 mix. Thats just as good as the guys running DA50, ZDZ50, BME50(at this altitude--6000'). The only thing that they have me beat on is the weight. And I doubt it's realy that much. You never can get a straight answer out of these engine manuf. as to the RTF weight of their engines. BME and DA advertise the stripped down- bare weight of their engines. Big deal, I'll bet my cylinder and case would weigh 2.5 pounds too!! I'd like to know what a DA50/BME50/ZDZ50 REALLY weighs when it's RTF with the muffler and battery and prop. I'd venture a guess that it's over 4pounds-- maybe even over 4.25 pounds.

I'm really happy with my engine. I've got another one just like it out in the garage. It's been cut up- but no ignition or parts made for it yet.

Rcpilet, that was quite a description of how to convert the engine ! I wont need a carb adapter, mine bolts right to the cylinder with an adapter. The case I have is a bit bigger than the one you started with. The fuel tank on my saw was inside the aluminum case. I have been looking it over and think I might be able to do a flat plate on the backside. It doesn't look like the 180 degree flip of the cylinder and crank would benifit me with the case I have. Here is a couple of links to pics of the case I have.

[link=http://home.bresnan.net/~superfast/files/engine1.jpg]Engine Case Picture 1[/link]
[link=http://home.bresnan.net/~superfast/files/engine2.jpg]Engine Case Picture 2[/link]

Scott

scott I think your case must be one of the older saws ,does it have needle bearing and a long crankshaft? Kenneth