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Sithl 038 Rebuild / Super -> Magnum Conversion

paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
Nothing new or particularly interesting for most here but thought I'd document a recent rebuild / conversion of a Stihl 038.

Ever since building my Chinese 660 kit and reading countless times the usual comments along the lines of "steer clear of the kits and just rebuild a genuine saw" I have been on the lookout for a project. In 18 months of looking I had not come across one project worth even considering and came very very close to just ordering another kit. Then a very rough looking saw popped up on Ebay locally which was presumed to be an 038 by the seller (I could tell from the photos he was right). If only for the fact it was only 15 mins away I made a bid and surprisingly won it for £46 or $62 - my max bid and a figure that I literally guessed on the spot that I could make back if it was beyond repair and had to split for parts which I could sell on.

The following few photos are lifted directly from in the Ebay listing:

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I could tell from the photos that it had been on fire at some point and had been worked to death. I didn't for one second believe the claim that it would actually fire but not run and figured a new top end would be needed.

I collected the saw and only had one surprise... a very tatty bar but a virtually new recently ground Stihl RM chain on it - this saw was in absolutely no condition to need a chain at all let alone a decent one :wtf:

As was expected no compression at all - I didn't even bother to test the claim it would fire. Off came the muffler - sure enough P&C were scrap:
038_6.jpg

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I'm guessing the wrist pin circlip let go and went through the transfer port.

The cylinder measured 50mm which makes it a Super. OEM top ends are hard to come by and 90% of AM appeared to be for the 52mm Magnum. I already knew a conversion was possible and so made the decision there and then to make the saw into a magnum albeit a AM version. Made a Hutzl order for P&C, plastics , muffler and all the other bits and pieces I could see needed replacing.

Realising I had at least 2 weeks (possibly more due to the Christmas holidays) before the bits would arrive I stripped the rest of the saw down to clean but only got a few minutes into that before deciding that I also had enough time to re-spray the metal work which was seriously tatty and rebuild the bottom end.

First job was to make the case splitter using the plans kindly shared here:
https://www.arboristsite.com/community/threads/case-splitter-homemade.245737/

3mm MS side plates had to do as that's all I had to hand:
038_8.jpg


It worked better than I could ever have expected and I had the cases split before the welds were even fully cool.
Pulled the seals pressed the bearings out and I was ready to prepare the cases for paint:
038_9.jpg


I decided to make use of the sand blast gear put the case halves back together, plugged up all the holes and masked up all the with tape, tissue, heat shrink, hot melt glue etc whatever would work to protect the critical surfaces. A few hours blasting left me with a decent surface ready for paint:
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Yes I did notice I'd missed a few spots which I sorted with a second round of blasting.

Everything had a good coat of epoxy primer cooked off above the stove:
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I used some fine filler to sort out some of the pitting and the primer keyed lightly before getting two coats of light grey 2K Gloss (RAL7035)
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The paint was allowed to dry fully over the few extra days it took to order the bottom end parts from online - the local Stihl dealer insisted that a gasket set #1119 007 1050 didn't exist - he wouldn't even look and kept insisting he'd have to order all the bits in specially - which he quite clearly was too lazy to do in the run up to Christmas :mad:. I left empty handed with my money never to return...

A few hours each day after work saw the OEM bottom end back together after I thoroughly cleaned every last remaining particle of grit from the metalwork. That is the downside of grit blasting but the finish, I think, is worth it.

With the Chinese parts still at least a week away I read and re-read the guides posted by Mad Professor (and others of course) here on the forum:
https://www.arboristsite.com/community/threads/038-super-cylinder-questions.113258/

With all that digested I got on with assembling what else I could whilst waiting on the top end to arrive:
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Half expecting the AM parts to arrive after Christmas I set it aside for a few days to get on with other jobs but to my surprise they showed up early. With the cylinder to hand I could now see that I would need to modify the case to provide clearance for the base of the cylinder (despite it being a Super). Stupidly I didn't take any photos (I was itching to get it together and fired up and forgot) but this bit is well covered in the thread I linked to earlier and other links contained within it. The only thing different I have to add is that with my dremel (cheap nasty copy) out of action and my die grinder way too big and aggressive for the delicate job of removing that step in the case I used a very sharp wood chisel to slowly pare it away (a tool I am plenty familiar with and that I knew would work on soft Magnesium Alloy) A quick tidy up with a fine file was enough to convince anyone that it could have been like that from the factory.

I slotted the cylinder bolt holes with a 5/32" file taking my time and having marked everything out carefully beforehand using the gasket as a guide. I turned the cylinder bolts down from approx 10mm diameter to 9mm on the lathe rather than cutting clearance for them on the cylinder itself. I did not need to open the holes to provide any clearance for the T-27 driver which was a bonus. All in all maybe 2 hrs work going very steady - next one I reckon could be done in less than a quarter of the time it was that easy.

With the top end finished I put the rest of it together (not forgetting to pressure and vac test it along the way):
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The handle may get a bit of a clean up at some point but then again I may not - not because I can't be bothered to do it but more as a reminder of what that saw started from - same goes for the partially melted plastic cover on the rear handle - as I've already experienced having shown the saw to a few people those bits are the talking points on what might as well be any other brand new looking saw... until you show them the before photos.

There are at this point a few bits still left to finish - model badge (which will not actually fit the MS380 style top cover) - I may source a new 038 style cover but again I may leave it as is - it gets people guessing what it could actually be. I do have an OEM rim sprocket kit on order as the old spur is definitely worn out. I also have a Tillotson carb repair kit on order which I think will iron out the hard starting from cold.

Wearing the 20" bar and chain it came with:
038_21.jpg


Proof that it actually runs:

Second start with 25:1 and still running very rich I quick test cut running like that tells me it's got plenty of power obviously not in the same league as the 660 but also in a different league to the 028 Super. I'll hopefully get a better video of it in use when the last few bits are finished off and the saw gets put back to work (hopefully for another 30 years)
 
Big_Wood

Big_Wood

westcoast dweller
Joined
Dec 11, 2012
Messages
7,335
Location
Canuckistan
nice work man, so was the OEM saw more satisfying even with chinese parts? eventually you don't look for projects anymore. you appreciate the break in between them showing up! lol nice to start with a complete saw and one day you will find a diamond in the rough!
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
nice work man, so was the OEM saw more satisfying even with chinese parts? eventually you don't look for projects anymore. you appreciate the break in between them showing up! lol nice to start with a complete saw and one day you will find a diamond in the rough!

Good question and the short answer is no I didn't find this one any more satisfying than the Chinese kit tbh. The longer answer.... it's satisfying to see a saw, as abused as this one was, live again but for my uses I've struggled to get past the fact that this saw isn't going to work any better than the Chinese clone despite costing similar amounts (I've yet to total all the parts) take into account the vast amount of time spent and tedium of cleaning all the crap off the parts before reassembly and suddenly restoring a saw like this when a clean kit is available makes very little sense imho (at least for a saw in this poor of condition to start with). I'm sure that's not going to be a very popular idea here at all.

For something more exotic or requiring far fewer parts and less time to fix on the other hand makes much more sense.
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
I did get a new OEM metal 038 badge and Magnum decal and whilst just putting them on loose to see what they might look like it reminded me of an irregularity (not significant enough to be considered an issue) with the Farmertec Cylinder....
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As you can see the sprocket side mounting screw is not in there - for one very good reason it's miles out of alignment with the threaded hole in the cylinder - notice the small black dot on the cover to right of the grommet - that's roughly (going by eye from the outside) where I would need have the mounting screw. My first thought it must be because its an MS380 top cover... but no the original 038 top cover has the hole in the same place the plastic is spot on - so that leaves the cylinder which seems very odd can't see how they would be that far off with the cast boss :wtf:. If I had more time I'd whip the top cover off take a few measurements and photos comparing the OEM cylinder with this FT one - see what the weekend brings...

Whatever the case I'm not going to rush into doing anything about it for now - it's sturdy enough without a fastener.
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
I believe it's the top plastic part that's amiss. Mine has the fastener hole next to the handlebar. Mine also has a hole for a de-comp which my saw doesn't have.
I had another look - definitely something odd going on - as I say the AM top cover exactly matches the original OEM top cover (apart from the extra plastic below the hole of course):
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Lining the cylinders up:
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Holes definitely in a different place. The top cover in your photo above definitely looks like it would fit the AM cylinder I have hole placement is far further forward.

As I say it's not an issue really but it's certainly made me curious as to what was going on.

I can tell that some of us are operating on a completely different budget...I can barely afford AM parts!

You're not alone in thinking - this build at 100% OEM would have been too expensive to be worthwhile but I'm no collector and never envisaged selling it so I wasn't bothered about using some AM parts - I would, though, swap out the AM parts if I ever come across OEM parts for sensible money until then I'll just run the saw and probably at some point completely forget that its not OEM - at least that's what happened with other saws I've resurrected.
 
a. palmer jr.

a. palmer jr.

Tree Freak
Joined
Apr 8, 2007
Messages
13,983
Location
Southern Indiana
Unless you run into someone who's charitable I doubt you'll find OEM cylinders and such very cheap. My aftermarket P/C hasn't given a bit of trouble, just had a little trouble with the carb and choke early on. Also a bit of trouble with the air filter cover fastener. I think it's pretty well ironed out now..
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
I thought it was worth updating this build thread as I've now had a chance to use the saw a little.

Ever since putting it together I've had a nagging feeling that I shouldn't have used the FT piston rings... they were noticeably narrower in places around their circumference the end gap was also 0.016" as new. Well the saw ran perfectly fine and would probably have been perfectly OK for the amount of use it's likely to get. After running in with the FT rings the compression settled to 150psi.

Curiosity and that nagging feeling finally got the better of me and I ordered a set of Caber I cast rings for it. I've read a few concerns on here that caber rings are too hard for FT cylinders but decided to experiment for myself. Comparing the FT rings with the poor FT ones it's easy to see the quality difference...
rings.jpg


Installed the caber rings had a far healthier end gap of 0.01"

I decided to reassemble minus the base gasket (this dropped the squish to exactly 0.02") pulling it over said straight away that compression was up but I didn't get time, before having to run it this morning, to check with the guage.

I stuck a 25" bar with 3/8 Stihl RS Chain on it and put about 5 tanks of fuel through it today cutting up an old spruce (120yo counting rings) which had succumbed to high winds a few months ago. It ran well straight from the off and got smoother and gained power with each tank of fuel. I will stick the guage on it tomorrow to see what the compression is now.

All in all I'm very happy with how it's turned out If the caber rings prove to be a bad choice further down the line I'll loose no sleep the saw paid for itself in firewood in just one mornings work...
spruce.jpg


The haze is from the fire nearby not the saw!. The saw in the foreground is a FT MS660 clone with 3' bar and 3/8 Oregon LGX which also ran flawlessly all morning.

A poor clip (I cut it off by accident) of the very first cut with the new rings with the operator (not me) really leaning on it (he'd just come from cutting with his Husky 281 XP torque monster)
It certainly would have cut better than that nearer the end but forgot to take another video...
 
paul99

paul99

ArboristSite Member
Joined
May 20, 2012
Messages
92
Location
Wales, UK
One more detail I left out yesterday was that I also replaced the old worn out spur with an oem rim sprocket... I started with an 8pin rim but had a 7 pin to hand if needed. With the way it ran I certainly didn't see any reason to switch it.

As promised I decided to check the compression this morning... The Guage climbed to around 175 - 180psi but as I raised it to get a closer look and a photo the perished rubber hose couldn't handle the punishment
... notice the split just above the brass :laugh:. 20180204_125815.jpg

Accurate reading and photo to come (once I've had a chance to fix the guage).

Edit...
Guage bodged up for now and the compression is at 185psi...
20180204_163349.jpg
Out of curiosity I'll open the muffler up a bit and look at advancing the ignition timing a little at some point...
 
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