McCulloch Chain Saws

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No some are different just tore my Pro Mac 60 apart after I pressed the pin out of the piston I noticed one skirt shorter not just alittle either
Should have been paying attention but I think the shorter skirt is intake side can't see a shorter exhaust side doing anything. neither my old or new piston
has a ex marking. Anyone know for sure?
I see, thats a major difference there. I may have to go dumpster diving tomorrow morning before the garbage truck just to see!!!
 
That cp70 looks like regular 10-10 style porting. I can't take a picture but the 10-10 has those 3 "finger" ports. The S however does not I wonder what the 55 and 555 have.

Hang on a min here the 10-10 piston??? Its not windowed it's like the thick ring 7-10.... the full skirt style. 2broke says his maybe has the 3 fingers. Maybe its supposed to have the older piston maybe that CP has the older type. Is it a thick ring?
 
Are you going to run this saw? I mean like work it , or is it a piece of your collection?
I have saws that don't go to work with me so no offense intended .
That’s the plan. The last two I did are really clean, especially the little pro 10-10 so they won’t see much use. With this one being cosmetically challenged I won’t feel bad about beating on it lol. The 1-70 I’m going to take down to the vintage saw competition at the antique power show and have some fun with it.
 
That’s the plan. The last two I did are really clean, especially the little pro 10-10 so they won’t see much use. With this one being cosmetically challenged I won’t feel bad about beating on it lol. The 1-70 I’m going to take down to the vintage saw competition at the antique power show and have some fun with it.
Cool , I'm interested in how the polished piston will do ,
 
Cool , I'm interested in how the polished piston will do ,
I got it running last night, but I have a fuel delivery issue I need to sort out. The PO did the welch plugs and I wonder if he screwed something up. Anyways I want to run the snot out of this thing and see how well my work holds up :)
 
Here's my cp70 cylinder. Sorry I don't have it apart, but looks like the top of 3 finger ports to me.

I'll be darned. Can definitely see it in that pic now.

According to the ipl cp70 cylinder is #83222.

I'm in IPL exploration mode this morning and found the 83222 for the 11 and 12 prefixes and 84174 listed for the 10 prefix 'L' model and the 13 prefix saws. All list the 69030 piston which I believe to be the earlier full skirt 'port hole' style.

I'm also compiling cylinder pics and rooting through old posts for piston pics as well. I know Mark has posted several in the past. Just need to find em. Would be nice to have corresponding 70cc p/c pics all in one place!
 
Ok. I seem to be mistaken on the 69030 piston being the full skirted one. Here's a post from Mark that I was looking for that touches on the subject....

Earlier 7-10 models like mine had thick rings (63290/87166), but looking through the IPL's I see some later models did have thin rings (89732). To confuse the issue, if you look at the McCulloch cylinder/piston charts you will find the same piston (85239) described using the thick rings (87166) and the thin rings (89732). I think in fact the piston used with the thick rings was 69030 or 85240 but they weren't very careful when they were printing the piston/cylinder lists. You won't find 69030 in any piston/cylinder list but it appears in the IPL's.

Unfortunately is was common for these saws to be run too lean and scored, the SP70 and PM700 were more likely to be scored than the 7-10 in my limited experience. Those both happen to be chrome bore models and I have 3 or 3 PM700 saws and a couple of SP70's in the attic that suffered such a fate.

The early 7-10 saws had a cast iron bore and seemed to be less prone to scoring problems.

A long while back Steve AKA 6-10 asked about the 6-10 vs 7-10 pistons so I took some photos. The piston on the left is from a later model 7-10 with the thin rings PN 85239, the piston on the right is from an early 7-10 or 6-10, PN 85240.

70cc Pistons.jpg

Mark
 
Ok. I seem to be mistaken on the 69030 piston being the full skirted one. Here's a post from Mark that I was looking for that touches on the subject....

Looking at those pistons the later model 7-10 with thin rings looks like my pro mac 60 piston with the shorter skirt. Haven't pulled my 7-10 down yet I wonder what piston I'll find
 
I think my problematic 7-10 has those finger ports but it's been a long time since I looked at it.

Can't say that I blame you, but it's still driving me crazy. Gotta be something in that damned top end since it seems like virtually every other part on that saw has been swapped out.

And I'm way ahead of you, Vinny. LOL I wouldn't take these numbers to the bank, but they're pretty much all that's out there. Like Mark said, it's kinda funny there's no mention of the 69030 anywhere in the lists when it appears like it could have been the piston for early 7-10s. Even weirder is the 85239 being listed for what we know are both types of transfer designs and even the earlier non-chrome cylinders.

1982 70cc P-C and Ring Sets.jpg
 

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