Correcting squish on McCulloch cylinders

[ZERO]

In their day, they did some amazing work for us when we use to go into the woods and prepare our winter stash.

She is now in full retirement in the museum of saws that started it all for me.

Had her up in the attic, never got around to her till this spring.

Did not know how to: tension, sharpen, cut, maintain, dress, start and such.

Small scar on the filter housing, got semi runned over by the tractor. Me feeling a bump while turning, oops too late.

These ones bring back a lot of great memories, even when we did not exactly take care of her that well.

 

[Squareground3691]

In their day, they did some amazing work for us when we use to go into the woods and prepare our winter stash.

She is now in full retirement in the museum of saws that started it all for me.

Had her up in the attic, never got around to her till this spring.

Did not know how to: tension, sharpen, cut, maintain, dress, start and such.

Small scar on the filter housing, got semi runned over by the tractor. Me feeling a bump while turning, oops too late.

These ones bring back a lot of great memories, even when we did not exactly take care of her that well.

View attachment 380722



View attachment 380721

There day will always be here , Lol

 

[Stump Shot]

So, finally, I get to do an update on this saw here see. I won't bore you with the standard procedure kind of stuff, rather go into something different and why. As for the why, this saw is going on a really long trip and be somewhere where it has little to no support. So, I decided after much deliberation, that the compression should be reduced back to normal levels, so that A, it will be easier on the bottom end, and B, easier on the pull starter mechanism as well. The combustion chamber is quite small and has the spark plug located dead center. Reshaping the chamber did not seem like a fun proposition, so after running a new 562xp saw with the new dished piston and seeing that it still ran well, I decided to make something similar for this PM 610. I decided I would keep a ring around it the size of the squish band and remove as much as what the cylinder was dropped, this should still leave a small net gain on compression and keep the big net gain in efficiency with the squish tolerance adjusted, at least in theory, or so I supposed.
Now to get to getting, I taped up the piston but good to keep it from marring in the lathe chuck and lined it up and cut it. Fairly straight forward operation. With the final finish cut completed, all that was left is reverse the procedure and get it back together again with all the other mods completed and see what we did... and here it is.

 

[Stump Shot]

Some pics...

 

[Stump Shot]

Here's so you can see what I mean a little bit more.

 

[Stump Shot]

Not a bad looking rig by any means.
@ZERO

 

[Stump Shot]

A special thanks to @farminkarman for his excellent machine work on this interesting project. I believe it was done much better than necessary and would pass the most stringent of inspections possible.

 

[Stump Shot]

At the end of the deal, it cut better that stock and should last a long time, as these were fairly well known for the toughness. The only problem I encountered was a sticking inlet needle, which is not uncommon for something that sits a long time. Which after repairing the saw started in a couple of pulls, that by the way "feel" similar to stock saw. So I'm going to be so brash as to put this one in the win column and let USPS do the rest come Monday.

 

[ZERO]

Big thanks to both Steve @Stump Shot and Greg @farminkarman.

Before OPE I never thought a day like this would come.

This means more to me than you guys know.

Nice to have the expertise and down to earth reliability from such a good buch of guys.

 

[Squareground3691]

A special thanks to @farminkarman for his excellent machine work on this interesting project. I believe it was done much better than necessary and would pass the most stringent of inspections possible.

Sure do enjoy the Mac’s, old school torque

 

[Al Smith]

The old cinder blocks must be the most scoffed at chainsaws ever built yet they are nearly bullit proof . I have three which I seldom use only because I have larger saws that are lighter .The one I inherited from my dad has been"enhanced" by the old man and in the day would out run a Stihl 042 .

 

[ZERO]

To step back into the classics:

1. A very honest two way communication between the builder(s) and the customer must exist.

2. An absolute trust between the builder(s) and customer must exist.



Without these two very down to earth qualities, projects like these could never come to fruition.

This journey has taken on many twists and turns on the back end, but the end results speak for themselves.

 

[drf256]

Great job men. I’ve been wanting to dish a slug for sometime now, thank you for trying.

 

[Stump Shot]

Great job men. I’ve been wanting to dish a slug for sometime now, thank you for trying.

It was over much deliberation to come to this decision, however good or bad it may be. When reliability, durability and longevity became top priority's, the tough decision became easier, with the hopes of increased efficiency to win the day.

 

[ZERO]

Greg and Steve amazing project!

Steve, very well packaged for the international ride, nothing broken or missing.

Steve, the Express International shipping rate you quoted for a saw this size and weight - simply amazing.