Author Topic: McCulloch resleeve  (Read 1315 times)

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Offline 604f_1

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Re: McCulloch resleeve
« Reply #20 on: November 08, 2014, 06:57:06 pm »
The way to cut ports is to press the sleeve in the cylinder without any ports , give it a good bath in acid , take it out and voila . This process is called port etching .

Offline Al Smith

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Re: McCulloch resleeve
« Reply #21 on: November 08, 2014, 09:09:11 pm »
Explain to me how does one pull out a heat shrunk pressed in sleeve other than bore it out .These are not slip fit sleeves .

Offline 604f_1

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Re: McCulloch resleeve
« Reply #22 on: November 08, 2014, 11:05:17 pm »
Sure worth the read , some pretty cool projects , even some chainsaw related !
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop/page4

Offline Al Smith

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Re: McCulloch resleeve
« Reply #23 on: November 09, 2014, 05:13:26 am »
That is ingenious but it is an open cylinder with a head .With a blind end cylinder like a saw engine once you pressed the liner you have no way to pull it back out .With a heat shrink fit it's almost as rigid as if the liner were die cast into the block like a modern aluminum block automobile engine .

Plus the fact on that M/C engine there's enough room to use a thick walled flanged sleeve .Now what a person might be able to do is port map it and cut the ports undersized and press it home then finish cut the ports .It's only speculation on my part if it would work or not or just be an exercise in futility .

Offline 1manband

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Re: McCulloch resleeve
« Reply #24 on: November 09, 2014, 09:51:51 am »
cool link 604f1. 

the acid idea is interesting.  wonder if just making a port map on paper, then wrapping it around the new liner to scribe port outlines would be similar?  either way, it would seem difficult to get port angles correct.

Al, think you nailed it.

do you think there is enough room to counterbore the jug flange for locating pins for the liner after mapping?

just trying to pick up the scraps you guys are dropping to learn.

-joe



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Offline Al Smith

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Re: McCulloch resleeve
« Reply #25 on: November 09, 2014, 07:20:36 pm »
Unless it had a head you'd have to pin it at the bottom .Then you have the problem of hitting the pins .You've  got to remember that motorcycle cylinder is huge compaired to a chainsaw.That guy in the vid claimed it swelled 10 thou from the heat .You never get that much on a saw cylinder .I only heated my cylinder up at 350 in an old oven .Heaven forbid I do it the wifes oven .

Even at that with around 2-3 thou interference fit and a frozen cylinder it took some pressure the get the sleeve in .

About the only thing I've seen flanged sleeves was on wet sleeve cylinders like tractor engines .Usually on a dry sleeve they just cut from the top down and leave about 1/2-3/4 inch uncut at the bottom of the cylinder .Press the sleeve and mill the  top off flush with the head deck .Almost nobody dry sleeves an engine any more for repairs other than some very rare engine .

Offline Al Smith

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Re: McCulloch resleeve
« Reply #26 on: November 09, 2014, 07:43:17 pm »
Now I have a very vivid imagination so bear with me .An idea which may or may not work .It's only theory and conjecture that it might .Application would be a race engine .Much ado about boost ports ,finger ports ,external ports and the like .
They all do about the same thing only use different methods .So what would happen if say a stock cylinder were bored 15 thou over ,finger ports ,shallow cut in the cylinder wall .Could be two,could be 4 terminating right above the intake advanced 3-4 degrees ahead of the main transfers ,press in the sleeve .Cut the sleeve further down to ID size with port mapped template and do the ports .You'd probably have to stay fairly close to stock bore to save the cylinder wall strength .

What you could get might be better than externals ,that much advance before the main transfer would really boost the velocity .You would not need to reverse the piston or move the ring pins or worry about snagging a ring .Cut the extra ports with a hard upward angle to sweep above the intake but enough not to short circuit right out the exhaust .Who knows might work .It also might give you enough extra sweep you could leave the exhaust port long and really hang on to the torque .

Offline 1manband

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Re: McCulloch resleeve
« Reply #27 on: November 11, 2014, 08:35:08 am »
Now I have a very vivid imagination so bear with me .An idea which may or may not work .It's only theory and conjecture that it might .Application would be a race engine .Much ado about boost ports ,finger ports ,external ports and the like .
They all do about the same thing only use different methods .So what would happen if say a stock cylinder were bored 15 thou over ,finger ports ,shallow cut in the cylinder wall .Could be two,could be 4 terminating right above the intake advanced 3-4 degrees ahead of the main transfers ,press in the sleeve .Cut the sleeve further down to ID size with port mapped template and do the ports .You'd probably have to stay fairly close to stock bore to save the cylinder wall strength .

What you could get might be better than externals ,that much advance before the main transfer would really boost the velocity .You would not need to reverse the piston or move the ring pins or worry about snagging a ring .Cut the extra ports with a hard upward angle to sweep above the intake but enough not to short circuit right out the exhaust .Who knows might work .It also might give you enough extra sweep you could leave the exhaust port long and really hang on to the torque .

+1 lots of potential there.  with a sleeve, think the possibility of lowering the exh roof would also be available for a torque style build.

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Offline aclarke

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Re: McCulloch resleeve
« Reply #28 on: November 11, 2014, 09:22:09 am »
Al, how did you mark and cut the ports on the Mac you re-sleeved?

Offline Al Smith

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Re: McCulloch resleeve
« Reply #29 on: November 12, 2014, 08:40:37 pm »
I tried to find a picture but I have no idea where they went .Any way it goes like this .

The reed valve Macs area all built about the same way .Carb on top of a reed valve so no actual intake port expect the manifold which holds the reeds .Transfers top and bottom ,exhaust out the side ,horizontal engine .Bottom transfers are bottom tunneled ,three ports ,top kind of open three ports ,non windowed piston .Bottom tranfers are plugged with welch plugs .

The sleeve or liner only extents to below the bottom transfer tunnel .Leaving the welch plugs out all the ports can be cut right through the old ports left in the block and of course reinstalling the plugs once that's complete .The trick is chamfering the dang things without a right angle die grinder which I don't own .

Because the liner is cast iron they can be ground using a long shank tool .However working with a mirror every thing is backwards with regard to movement of the die grinder .It's not that difficult just tedious but then again any port work is tedious no matter what engine it is .If you aren't in the mood what until you are .Lotta work there to screw it up with a temper tantrum . ;)

 

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