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Porting another 350

Discussion in 'Chainsaws' started by isaaccarlson, Aug 14, 2018.

  1. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    It’s been a while since I’ve been on here. The last few years have been crazy, but I’m getting back into saws a bit. A few of you might know about the 350 I built for a friend a couple years back, and fell in love with. I asked him if he would sell it back to me and he said “no way, it’s the best running saw I have, but you can use it here whenever you want”. Well, a guy has to have something he loves. I picked up a 350 for myself this spring, and am in the process of working it over. It’s an older model(1999), but it seems pretty solid.

    This one was put together with silicone, just like the last one, so at least I knew what to expect when tearing it down. This is a work saw, since I do a few tree removals and cut firewood. I have a 45 mm cylinder (with removable transfer caps) along with a hyway 353 flat top piston. I really, really like this piston because of the way it can be modded for better transfer flow. I used the same piston on the last build, and it turned out great. I could really lean on the saw and it would just keep cutting.

    I’m seriously considering stuffing the lower/mid transfers(something I didn’t do on the last build). There are some steps in there that make a good bit of turbulence, and I want to get the case volume back down after removing so much material from the piston.

    The base gasket has been removed and the base has been surfaced flat on both sides, bringing the squish down to ~.020. No popup. The exhaust will be ~65% of bore(straight line measurement), as will the intake. Port timing will likely be close to stock. I like to keep a long power stroke, good blowdown, and a short, strong intake surge to pack the case. This provides plenty of torque to keep the chain moving. I’m a “straight six” truck guy, so I have an appreciation for good torque. I have no problem filing rakers.:D

    The muffler will be modded, opening up the entire area under the deflector and a bit of massaging the deflector plate. That’s plenty. The mufflers are already open inside, so there is no need to cut them open.

    I believe this saw has an unlimited coil, being a 1999 model. I don’t know what the timing is just yet, but I will find out and advance it if I think it’s needed.

    The oiler will get modded, since they are pretty weak from the factory, and a working chain needs a lot of oil.

    Compression release? What’s that?:rolleyes:

    I don’t have any pictures just yet, so hold tight, they are coming. :tiburon:
     
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  2. Dub11

    Dub11 Some body poisoned the watering hole!

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  3. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I have a few thoughts/questions about those. Are they open on the inside or solid? How much do they weigh?
    If they are not solid, will they trap some charge between them? How will the saw rev with them in place? Added rotational weight is great on a brush cutter, but not on a saw.

    I guess i’m interested and intrigued.
     
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  4. Dub11

    Dub11 Some body poisoned the watering hole!

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    The newer Huskies have stuffers on them so it has to be good.
     
  5. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I have not messed with anything “new” in almost 10 years, lol. I think it’s interesting tht the new saws have stuffers. I wonder what the case volume is on them, because I don’t think they would fit in this saw. The clearance between the crank and case is almost nothing. I have worked on saws where you could fit a mouse in the case with the crank, but not this one. What year is the 350 you have and is there room for them?
     
  6. Dub11

    Dub11 Some body poisoned the watering hole!

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    I haven't tried them yet.
     
  7. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I was looking at the case on this saw, and they would have to pretty darn thin to even fit in there. I’m not worried about it right now, so I’ll just leave it the way it is.
     
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  8. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    Sorry for the slow progress on this, work is keeping me pretty busy. I have been trying to figure out just exactly what I’m going to do to this saw. I know I want to stuff the lower transfers, and have already trimmed the piston to my liking. I took the squish down to ~.019 and actually used a degree wheel to get some numbers for my notes. I normally don’t use a degree wheel and just do it by eye. The transfers need to get raised so they open all the way. They don’t open all the way to begin with, and reducing the squish only made it worse. They only open about half way now. If I raise them ~8* or .065”, they will open all the way and blowdown will be right at 19* according to the wheel.

    I think I might stuff the upper transfers to bring the bottom edge up to the piston crown at bdc to improve the short side radius and reduce turbulence. I have an ample supply of JB Weld, so I might as well try it. The last 350 I did had the transfers widened but not raised. It turned out very strong, but I think I left a lot on the table. This one will get the last few treatments to see what it will do. I need to pick up a few new carbide burrs, and then it’s go time.
     
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  9. Adamski

    Adamski Plebus Splederns

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    Good info, what did you do to the piston to help the transfer flow? I have a 351 with a 353 top end. This winter I will be pulling it apart. I am intrigued by a hyway 353 flat top too
     
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  10. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I trim off the “ears” as I sometimes call them. Here are a few pictures. Before, half done in cylinder, and finished. This really lets them breathe. This is my go-to piston on these saws. You can see how much it opens up the transfers and that ear really makes a big ball of turbulence in the transfers once the air starts moving. I don’t know if anyone else does this, but I do. Hang on tight if you do this, it really peps ‘em up! I work over the transfers more than anything else on the saw. There are a lot of transitions and sharp edges that really hurt the flow.

    Before
    8DB93CF3-9656-4985-ADE0-2CA88FD4BE6F.jpeg

    Half done
    7AEB20E6-BCE2-4952-B61B-C1C61BEF61DD.jpeg

    Finished
    9568B82D-537F-4EAD-9292-8436F2755E75.jpeg
     
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  11. huskyboy

    huskyboy Sorta a Husqvarna guy.

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    I can see the staining on cylinder base where it doesn’t match to the cases, do you take a burr and match it? I’ve done it on a few saws.
     
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  12. XP_Slinger

    XP_Slinger I like saws...sometimes

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    That’s pretty slick. Have you seen any issues with the piston from removing that much material after running it for a while?
     
  13. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    Huskyboy, some of these pics are from the last build, but yes, I match the cases.

    Xp_slinger, so far so good. The one in the above pictures has been running for 3 years now at ~14k with no apparent issues. The owner tells me it’s the best running saw he has, and he has a few bigger ones, so that says it all right there. It cuts at least as good as my ported ms390, and that one will eat some wood. I had a hard time giving it back, and it wasn’t even broke in yet. I only had 3/4 of a tank through it.

    These saws have a LOT of potential. A 350 with muffler mod doesn’t stand a chance against a properly ported and tuned 350.
    I can’t wait to get this one put together and warmed up.
     
  14. XP_Slinger

    XP_Slinger I like saws...sometimes

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    Glad it’s still running strong. Makes me think a 359 would benefit from a similar piston mod because the cylinder design is identical to the 350 you’re working with.
     
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  15. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    Anything that will allow smoother flow through the engine will increase flow because there is less turbulence.
     
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  16. NCFarmboy

    NCFarmboy Super OPE Member

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    IT does. ;)
    Shep
     
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  17. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I have been whittling away at this saw some nights after work and sometimes on the weekends. It has been a lesson in patience to get it done, but I’m almost there. I can’t/won’t post pictures of the inside unless it runs like crap. :eyepop: I gave away one of the piston mods, but will leave the rest for you to figure out. I figured the piston ear mod was low hanging fruit, so I threw it out there.

    This was supposed to be like the last build, but I got a bit carried away. I did a few extra things because I wanted to see if they would help. If this was someone else’s saw, there would be $400-500 in it by now. There is a ton of aluminum on my desk and floor, and the transfers can’t flow much better without some considerable engineering. I don’t know exactly where the power will be, but it should be there somewhere. :drive: There is no popup. This is “machine work” free, meaning it is all done by hand. Squish is in the high teens. This cylinder has a smaller chamber than the other one, from the factory. I’m waiting on a few more parts and t’s going back together.
     
  18. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    I just want to let people know what I found while comparing cylinders. I don’t know what cylinder was on the saw, but they are very different as far as porting.

    The old cylinder (which was a replacement as well) is open port, has a very wide exhaust port, tall and narrow intake, and small transfers with offset openings so they open at different times. The chamber is also bigger. I did not get any timing numbers from it because I was not planning on using it. What I do know is that it was very anemic, even with a flat top piston.

    The rest of my parts should be here shortly and then we will see how it runs
     
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  19. isaaccarlson

    isaaccarlson Well-Known OPE Member

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    Hey Dub11, how do you like the saw you got from t4driller? His build was similar to mine.
     
  20. Dub11

    Dub11 Some body poisoned the watering hole!

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    I only used it for some limbing before I gave it to my buddy. It definitely had some snap to it.
     
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