Skil 1629 type 3

[rmh3481]

Are you sure that hole isnt for impulse? Impulse runs the diaphragms in the carb. Some saws have channels cast into their castings for the pressure and vacuum beneath the cylinder to be piped off for this purpose. Others use hoses. Looking at the pics I would think the carb would sit above this location? Maybe check the top casting and see if it has a channel cast into it as well. Ive not worked on a Skil so I cant say for certain.

 

[stderr]

commencing reassembly

Still hoping for a guru to shed light on the mystery hole, but while waiting, I must get a move on. Working on reassembly, it looks like the best way to start is to clamp the cylinder upside-down in a vise, and stuff the piston in. There's an aluminium gasket between the cylinder and crankcase, which I cleaned up well, and sanded a bit with 600 grit. I did the same to the cylinder. Here's hoping they form a seal.

Next, I dropped the top half of the crankcase on, and inserted the crankshaft, bearings and seals.

Now for the fun part. The bearings:

These obviously required some cleaning. There are only 10 showing in the picture, but there are a total of 13. There's no cage, and they must be inserted one at a time. I tried all sorts of tricks to make this go smoothly. First I tried inserting them one at a time with a pair of tweezers. Didn't work, though I got 9 of 13 in. Next, I put the bearings around the crankshaft and held them in place with a zip-tie. Didn't work, as the crankshaft can't be inserted through the rod without bumping into the zip-tie. Tried using a rubber band instead, this time the crankshaft interfered with the bearings directly and wouldn't reach home. Talk about a humbling experience. Finally, in the end, the light came on. Put the rod through without the bearings, and push it all the way until the connecting rod sits in the groove on the crankshaft counterweight. Apply grease to the bearing surface on the rod, lots of it. Push bearings into the grease, and when all 13 are in place, slide the crankshaft over so the bearings are between the connecting rod ring, and the crankshaft. I should have asked after the first two hours of trying, it's a good thing I'm not stubborn. Here's what it looks like when finally home:

 

[stderr]

Are you sure that hole isnt for impulse? Impulse runs the diaphragms in the carb. Some saws have channels cast into their castings for the pressure and vacuum beneath the cylinder to be piped off for this purpose. Others use hoses. Looking at the pics I would think the carb would sit above this location? Maybe check the top casting and see if it has a channel cast into it as well. Ive not worked on a Skil so I cant say for certain.

Excellent question. It's not for impulse. If you look at the first picture in the "commencing reassembly" post, it shows the cylinder sitting upside down in a vise with the piston sticking out of it. On the left side just peeking around the piston skirt, you'll see a hole through the cylinder gasket. That's the impulse line. It took me for ever to figure out how vacuum got to the carburetor to run the diaphram pump. There's a bakelite block that goes between the intake port and the carburetor, and has a big hole for intake, plus a second, maybe 1/8" diameter hole. The little hole mates with a hole on the side of the cylinder base, and routes through the cylinder gasket into the crankcase. This is the impulse line. I thought it was pretty clever.

 

[stderr]

sealing the crankcase

With the bearings in place, and everything sitting nicely, time to seal up the crankcase, or at least give it a shot. Thanks to everyone's pointers, I found a tube of the famed threebond 1194 (already used a little in plugging the mystery hole in the bottom of the case).

There's a big groove in the top half of the crankcase between the crank chamber and the oil reservoir (see 2nd picture in "commencing reassembly" post). When I initially opened the case, there was a section of o-ring in the groove. It had cracked, deformed, shrunk, and partially worked its way out on the flywheel side. I'm guessing when the saw was initially assembled, threebond wasn't an option, so this was how bar oil was kept out of the crankcase. For this attempt, I chose to forego the gasket and fill the groove with threebond.

After similarly adorning the bottom half of the crankcase with threebond and letting it sit for a couple of minutes:

I then carefully mated the two halves, and tightened up the four bolts around the crank chamber, the two through the oil reservoir, and the one in the handle. Here's a few shots of the seam:

Clutch side:

Flywheel side:

Front:

After tightening everything up, threebond began oozing out of the seam all the way around. I wiped most of it off, but then out of paranoia thought it was probably also running down the inside of the oil channel into the oiler piston/cylinder. A few wipes with a q-tip revealed that yes some was leaking down the hole, but not nearly as much as I thought. It should now be pretty clean through the oil channel.

After all that, I pulled the assembly out of the vise, put in the plug, put a piece of innertube over the exhaust port and attached the back half of the muffler, put another piece of innertube over the intake port, and mounted the bakelite block to the intake. I had put a hole through the innertube so I could use the hole through the bakelight block for impulse as a place to vacuum test from.

It still leaks! It holds vacuum, but bleeds down. This is an improvement, but not good enough. I used a bike pump with a built-in pressure gauge to pressure test. This also failed. A little soapy water showed the clutch seal is the problem. It's not only leaking around the crankshaft stub, it's also leaking where the two case halves meet the oil seal.

I called a local seal company and gave dimensions for both seals. I came this far, might as well replace both. Of course, they have the flywheel side, but not the leaking clutch side. It will be a week before I see the new seal. So, I guess that's why I have time to write this up.

 

[stderr]

Building an Obsolete Saw for the Experience

The latest in my 400 part series, Building an Obsolete Saw for the Experience. How does the saying go? Experience is what you get when you don't get what you want.

The seals came:

New ones have the red finish. The flywheel side one is not as tall as the original, but I don't think that matters, so long as it's in straight.

I stripped the saw back to a bone pile, tried again. This time, I used more 3bond on both the two halves, and both sides of the aluminum gasket between the cyl. and case. There was some bubbling around this interface during the pressure test too. It still went faster. I'm getting better at handling those little pin bearings. Having the process down helps too.

This time, the leak-down test went better, but still not perfect. In the end, I just had to accept it. It's close to sealed, but I can't see bubbles coming from anything during the pressure test, and I can't hear any sucking noises using a piece of hose for a stethoscope.

Then came the sad masochistic realization ... :censored:
Interesting bit of trivia: you have to put the gas tank in place _before_ you seal the two case halves together. No matter how hard I tried to deform the plastic case, tried using a little heat, couldn't find my shrink-ray, all that work...had...to...be...undone . It serves me right for not making a note of this when I dismantled it in the first place.

Try #3, I think a reference to Groundhog Day should go in here. I budgeted the better part of a Saturday afternoon to disassemble, strip, clean off that 3bond (bonds really well, tough to remove). Those little plastic wire-wheels in a hand-drill work. I thought of Acetone, but didn't have enough on hand, and didn't feel like breathing it for 1/2 - 1 hr. This time, the saw went together like a house on fire. Since a successful leakdown test had eluded me to this point, I just put it together and didn't sweat it.

After all this trouble, a carb kit went into the rather large Tillotson carb with really no incident. I didn't bother with the Welsh plugs, just soaked the carb for a couple of days in varsol. Blew it out w. air, reassembled, new diaphragm, gaskets, that little needle that looks like a plumb bob (what's it called, anyone?)...

Next up was the coil and points. Is it possible to fit an old saw with an electronic ignition module and just remove the points? Are there timing issues? Too many variables?

The maker of the saw was nice enough to mould the required gap right in the plastic points housing. Nice.

Putting the flywheel back on brought a small surprise. I had cut the nut off the end of the crankshaft because I couldn't free it. When I went to buy a new nut, the first problem was that it's an NF thread, not carried at home despot. I found an industrial supplier, took the saw in, and we couldn't get the nut on. How common is this? It's a left-handed thread. This means it could spin off during saw operation if not torqued on really well. Eventually, I found the only place in town with a stocked left-hand threaded NF nut. I had to take stainless, and used loc-tite to put it on.

Note the plastic fuel tank sitting beside the blue spray bottle behind the saw. :monkey:

 

[chainsawwhisperer]

She's looking good! I laughed about your fuel tank debacle, I do that sort of stuff all the time
Jim

 

[stderr]

progress...

After the fuel tank debacle, and an afternoon of building, I had the saw back to where I realized my mistake. Some of the pictures show partial stages of assembly with the tank still out. In my impatience to get it together, I didn't pause for pictures most of the way along. Imagine hitting rewind, inserting the gas tank at the right spot, and re-assemblng up to where I left off.

I set the gap between the ignition coil and the flywheel using a business card as a spacer (thank-you arboristsite.com for this little nugget).

Hmm, things have started to snowball. How could they not after assembling the crankcase three times? I mounted up the clutch so I could put the bar on and clamp it in a vise. It's a little easier to work on when I'm not chasing it all over the bench.

I cut a gasket for the muffler out of automotive exhaust gasket material from Mr. Gasket. Speaking with a local saw guru, he told me that there were two chronic problems with this saw. One, the plastic spacer (I thought it was bakelite...oops) between the carburetor and intake port has a tendency to crack, and two, the mufflers just won't stay on. I used a gasket where there wasn't one before, lock washers, and loc-tite. I'll keep my fingers crossed. I noticed somebody has a new P&C for an PM340 on e-bay. It has gaskets for the muffler and the intake that I have never seen before. Mind you, the mating surfaces on the cylinder ports don't look all that smooth. The intake port doesn't look like it was milled.

Next, fuel delivery, or everything between the cylinder and the gas tank. I cut a gasket for the intake to go between the afore-mentioned "has a tendency to crack" spacer block and the intake port on the cylinder. The basic order is: gasket (doubles as a heat shield), spacer, gasket, carburetor, gasket, air cleaner bottom half. All of these go on in one piece, secured with two really long bolts. While getting this into place, attach the throttle linkage to the carburetor throttle lever, maneuvre around the idle adjustment screw assembly, oh and attach the fuel line while you're at it. Don't let any gaskets slip out of place while putting it in. My poor attempt at sarcasm aside, this was much easier than installing the rod bearings.

 

[stderr]

more progress...

The little Robertson headed screw to the left below the carb is the new tank vent. The original vent was a two piece plastic assembly with a spring and some other bits inside. I'm not sure how it worked because when I took it apart, the rubber and/or foam pieces inside had rotted out completely, and were just a gooey black mess at the bottom of the housing. I've read (on this site) that a piece of fuel line with a screw in it will work as a tank vent. Here's the old one next to the new one:

Next, I dropped in the flocked air filter screen and gasket, installed the spark plug, and screwed the cover plate onto the top. It's starting to look like a saw again.

 

[stderr]

still more progress...

In an effort to reduce the vibration, I thought I'd cushion the handles a little. I bought something called Insulone heater hose, as it had the right ID for the front handle:

Putting it on involved lots of swearing, grunting, swearing, sweating, begging, swearing, praying, swearing...why did I start this?

After the front handle was done, I got to the rear handle. I had noticed on a different specimen of this saw that someone had put a small chunk of garden hose into the handle body. This made the grip a little more round, and more comfortable. I did the same, then wrapped the handle a couple of layers deep with a sliced up bike innertube. After that, I covered the whole thing with hockey tape. Before and after:

One other thing I thought odd about the saw was that the bar mounting studs are ridiculously long. There were two brass nuts with washers between them on each stud, plus an extra 1/2" of stud sticking out past them. The brass nuts had been worked over so many times that they were misshapen, and not able to be tightened with anything but an adjustable wrench. I cut down the bar studs, and got some flanged steel nuts. This is less likely to catch on stuff, looks better, should be stronger, and easier to tighten. So, bar and chain mounted:

...before & after...​

 

[chainsawwhisperer]

In an effort to reduce the vibration, I thought I'd cushion the handles a little.
After the front handle was done, I got to the rear handle. I had noticed on a different specimen of this saw that someone had put a small chunk of garden hose into the handle body. This made the grip a little more round, and more comfortable. I did the same, then wrapped the handle a couple of layers deep with a sliced up bike innertube. After that, I covered the whole thing with hockey tape. Before and after:

I think the garden hose on the handle is a factory install, One of my Skils has it on both handles as well.
Jim

 

[stderr]

Yes, but does it run?

Time for a little test fire. I recall reading on a PM version of this saw that the mixture screws should be around 1 turn out each. I put them there, and tried to start it up. It runs, but I'm having a hard time tuning it. It just wants to run super rich. There's black goopy oil, I guess the term for it is spooge, coming out of the muffler and running down the front of the saw (see sludge trail on the right of the pic):

The spooge offered up a clue as to why I couldn't get a good vacuum or hold pressure for very long. The goo was accumulating around the spark plug too. It was leaking past the plug? I never would have guessed, and never thought to spray around the plug with soapy water. After a little clean-up:

I wrapped a little teflon tape around the plug threads and shoved it back in.

Subsequent test runs have not shown more goo around the plug, so I think that should do it.

There is also fuel all over the outside of the carb, and it's puddling in the intake under the air-filter, and running down the side of the carb. I thought the carb rebuild went smoothly. Given that I never actually tried to run it afterward, it makes perfect sense. Now that I've tried to put fuel through it...ah well, you learn more when there are problems. I suspect mixture is weeping past the mixture screws and breaching the metering diaphragm gasket.

It turns out Tillotson has a service manual available on-line for the HS series of carbs. I downloaded that, and read it (when in doubt...). Think I'm on to it, I pulled the carb off, opened the fuel chamber at the top, and could see the metering lever is pointed away from the carb at about a 20° angle. It should be level. I bent it down until flat, and reassembled. This helped quite a bit, but it's still not there.

If I completely close off the high-speed jet, the saw races like it's super lean. This might not be unusual. If I completely close off the idle jet (with the high-speed jet opened back up), the saw races too.

After pulling off the carb apart the second time, fool that I am, I expected victory. No. Third time's the charm? Thinking maybe I had a damaged needle seat, I pulled it apart carefully a third time. Reading the Tillotson manual, they suggest spraying carb cleaner and blowing out w. air. I read somewhere on AS that you shouldn't use compressed air, but if the mfg says do it, I'll go with that.

This time, instead of just soaking it in varsol, I sprayed carb cleaner through every orifice I could see, and followed up with air. I don't know what a damaged needle seat looks like. Should I see a crack, or marring, or something? I couldn't see anything, even w. a magnifier and a lot of light, so I reassembled the carb, and put it back on the saw.

 

[stderr]

Finishing up.

When the saw was running, the vibration was hard to miss. My teeth were chattering, and my fingers went numb within a minute. The flywheel has two broken fins, and it crossed my mind this might be a contributing factor. I pulled the starter off, removed the flywheel, and used an angle grinder to remove the remains of the broken fins. I then ground away two more fins, each on the opposing side of the already absent fins. I thought this would help with balance. I then re-installed.

When I restarted the saw, it was running even more rich than before? Lots of smoke, a sopping wet muffler, and after I shut it down, it wouldn't restart. ...but I never touched the carb!!! Well, except for the three times I stripped, cleaned, and reassembled it. The last thing I touched was the flywheel, and I noticed when I remounted it that the ignition coil was just brushing the magnet enough to leave a scratch on the face. Can this affect performance? I reset the coil using the business card trick as before. That helped a lot! It started about the same as before removing the flywheel, and after a little tuning, just sort of idles along without complaining, racing, stalling. It even seems to accelerate well. I held a blank sheet of paper in front of the muffler while it was idling, and no spooge appeared on the sheet. More importantly, the vibration was/is significantly reduced. Since the flywheel is really used to push air through the cylinder fins, I hope this doesn't reduce air flow too much.

Convinced the carb was OK, the next problem was the fuel tank. It's not sealing, and fuel is running out past the cap. This is not a little fuel, but enough to impact mileage and pose a fire hazard. The lid looks OK, but the tank opening is not flat, so the lid won't seal. I filed it flat(ish) and fabricated a gasket using 1/16" rubber/cellulose gasket material. It still wouldn't seal, so try try again. I emptied the tank of fuel, stuffed a rag inside, and C-clamped it by the bar to a bench. This left the tank opening pointed downward, so material wouldn't fall in to the tank as I worked on it. I then took a palm-sander to the face with 600-grit emery cloth. That cleaned it up very well. Another close look at the plastic lid, and I could see my hand-cut gasket was actually a little too big to fit into the lid properly. It was curling up against the side of the lid in a couple of spots. Since I had to buy a 12x18" sheet of the stuff, I cut another one, this time being careful to make it slightly bigger than the threads, but smaller than the ID of the lid. That worked. The tank's sealed!!!

There was an o-ring for sealing the oil reservoir lid too. This also leaked, even with a new o-ring. I thought I was on a roll with the rubber/cellulose gasket material, so I cut one for the reservoir lid. This worked too. The big bucks I paid for the gasket sheet seem to have been worth it.

Somewhere in the process, I threaded the oiler trigger linkage through the saw, and attached it to the oiler body and the oiler trigger. After adding a little oil, it still leaked. It looked like the culprit was a screw in the tip of the oiler valve housing. The oiler piston pushes toward the screw. I removed the screw, wrapped it in 4-5 turns of teflon tape, and threaded it back in. Hey, it worked on the spark-plug. Problem solved.

Earlier on, I posted several pleas for help on a mystery hole in the bottom of the crank case. rmh3481 (see post #21) thought it might be something to do with impulse. I dismissed that, as it's nowhere near the carb. rmh3481 was on to something, but it's not impulse for the carburetor. I read the PM340 spec on Mike Acre's site. It says "Automatic oiler with Manual assist". There's no gear driven oil pump on this saw. I think, at some point, there must have been a diaphragm in there to use crank case impulse pressure to pump the oil. When I pulled the oiler body off, everything came off in chunks, and had to be ground off with a plastic wire wheel. What a mess. If there was a diaphragm in there, it was unrecognizable, and where would I get a new one now anyway? I guess the saw is now strictly a manual oiler. In truth, it was all manual before I took it apart, as there was no oil hitting the chain unless the oiler trigger was used. I'm less concerned about the plugged hole now.

So, it looks like it's ready for prime-time, warts and all.

When I find a little wood to put it through, I'll put up some video.

 

[stderr]

A little video

Video of a little carb tuning and some test cuts with the saw. It's not perfect, but it does run.

<object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/oSMBAi9Rhks?fs=1&amp;hl=en_GB"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/oSMBAi9Rhks?fs=1&amp;hl=en_GB" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>​

Some of the text is a little hard to read, and my camera angle is a little low, my bad. I'm still working on my video shooting and editing skills. Everything is new.

Thanks to all for tips and pointers over the last few months.

 

[babrown]

If the crankcase pressure gives an assist to the chain oiling, then it might be a good idea to leave that hole unplugged,

 

[stderr]

It's a bit of a blast from the past now. The saw worked well enough with the manual oiler, but I could never get past the idea that if you left the case open you'd have more trouble getting fuel because there would be less impulse pressure to drive the carburetor's diaphragm pump. Why go to the trouble of sealing the crank case if you're going to leave an open hole in the bottom of it? Regardless of which is better, it's all academic now.

It had a more fundamental problem of low compression, the symptom a decreasing idle as temperature increased. Eventually the saw wouldn't idle without the throttle held a little open or the idle-screw cranked in; after letting it cool, it would idle high enough to engage the clutch and the chain would turn constantly. The saw met its end when the chrome finish on the cylinder began cracking, spider-webbing and flaking off. I was not prepared to invest another $200 in a new cylinder & piston for a saw of that vintage. I was learning how to rebuild and maintain saws at that point; I got what I wanted, and call it a win.

The saw was donated to a young punk-rock band for a prop in one of their videos. The first one to pick it up looked like he was falling in love and asked what it would take to make it run..