Now that it's clearly visible, that certainly appears to be a CP handle brace -- and probably the short block as well. Definitely worth measuring now just to confirm. The tag may well be correct after all.
McCulloch Chain Saws
- Thread starter Bruce Hopf
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Now that it's clearly visible, that certainly appears to be a CP handle brace -- and probably the short block as well. Definitely worth measuring now just to confirm. The tag may well be correct after all.
The fuel tanks on the 10 Series anti-vibe saws like the CP, SP, and PM850 ++ are sealed and are not meant to be taken apart. I did manage to disassemble an SP70 years ago but broke the screws and had to drill them out an install threaded inserts to get the tank back together. Even then it leaked so I ended up using a liberal coating of Threebond on the seam. I prefer Red Kote to POR15 these days but it that is all you have available it will work, in any case make sure the tank is clean and dry before you apply the sealer.
Mark
Mark
Yokosukadweller
ArboristSite Member
Thanks Pogo, and yes...I'd want to measure it. Noob question, what exactly do I measure now and against what number?
@heimannm thanks, yes I think I will leave some vinegar+baking soda in the tank for a while with some gravel, then antirust coat, then dry and apply POR, and see what happens.
Use a little acetone as the final wash, it will help get rid of any water that may be hiding in the pores.
Mark
Mark
Find the diameter of the cylinder through the exhaust port by inserting a straw (or something similar) against the opposite wall, then rotate the crank until the piston comes up against it firmly enough to make a mark or crease. Then measure the distance from the crease to the end of the straw.
CP55 will be 1.74" CP70 will be 1.99", SP60 will be 1.87" as listed below.
Thanks, I'll definitely try that out.
Sometimes unpainted engine parts mean replacement blocks or cylinders, which is a good thing with a used saw.
I'm just not certain on what models may have come unpainted from the factory.
Don't feel too bad about not knowing which models were unpainted from the factory, I am not sure the factory knew much of the time.
Mark
Mark
Yokosukadweller
ArboristSite Member
Thanks a lot! I will bookmark this. Very useful. And will try to measure it not that it matters but out of curiosity, since this seems to possibly not be the original engine either.
Definately a mystery saw there. Ducted muffler, sp bottom brace, looks like it was a succesful retrofit.
Ive split and resealed succesfully 3 super pro tanks. Ive also failed on 2 attempts. Ive found that the screws will break off but when heat is applied using vice grip pliers, the rest of the screw will come out rather easy. As long as theres enough to grab. I sealed them with jb weld on the seam. It works fine but is a lot of work. The screws they used are self tapping fine thread.
Ive split and resealed succesfully 3 super pro tanks. Ive also failed on 2 attempts. Ive found that the screws will break off but when heat is applied using vice grip pliers, the rest of the screw will come out rather easy. As long as theres enough to grab. I sealed them with jb weld on the seam. It works fine but is a lot of work. The screws they used are self tapping fine thread.
Good eye, Vinny. I stand corrected. A bit deceptive at first glance with the mid-brace buffer and ground strap..., plus the angle of the pic. Interesting adaptation (or McVariant?) nonetheless. Then there's the duct.... So should I stand by my original guess that it's a SP60? LOL
Not yet, you still have an oil tank off a cp saw. The sp saw oil tanks have the mount for the front lower buffer/av with 1 bolt. Your tank is not like that. You still have the mounting bracket and ground wire from a cp saw too.Id still lean towards a cp saw myself. Just a matter of which one.
Yokosukadweller
ArboristSite Member
Thanks for your great info. So with morning coffee in hand I opened up to the bore. Its the first time I ever done this (yes, newbie here), but as far as I can guess it looks clean and in really good shape no?
@PogoInTheWoods - I measured it to be just a tad over 5.2cm which is 2.04 or 2.05", so to me, this makes it all even more strange. If my measure was correct the engine block is from an SP80...if I am off, it looks to be from a CP70. But the origiinal serial was for a CP55 - but with 12 prefix, which seems to be only for CP70 or SP80....So no definite answer on model of this Mac...
Adding some pics:
I had to take a flap-wheel to the fuel tank to get the old JB weld off from the outside, as the person who fixed the leak before me had applied it a bit too messy. Tank is now soaking the insides in vinegar/baking soda, gravel to clean it. I will leave that for a few days and then seal with POR15. I probably want to repaint it. We don't have rustoleum yellow paint here, but I can find a safety yellow that looks to be about right, and a motorcycle semi-gloss black that is at least gasoline resistant (if not proof). Not in a rush to do this, but probably I will try to get this saw back to good shape, if I can get all the old grease off it.
@PogoInTheWoods - I measured it to be just a tad over 5.2cm which is 2.04 or 2.05", so to me, this makes it all even more strange. If my measure was correct the engine block is from an SP80...if I am off, it looks to be from a CP70. But the origiinal serial was for a CP55 - but with 12 prefix, which seems to be only for CP70 or SP80....So no definite answer on model of this Mac...
Adding some pics:
I had to take a flap-wheel to the fuel tank to get the old JB weld off from the outside, as the person who fixed the leak before me had applied it a bit too messy. Tank is now soaking the insides in vinegar/baking soda, gravel to clean it. I will leave that for a few days and then seal with POR15. I probably want to repaint it. We don't have rustoleum yellow paint here, but I can find a safety yellow that looks to be about right, and a motorcycle semi-gloss black that is at least gasoline resistant (if not proof). Not in a rush to do this, but probably I will try to get this saw back to good shape, if I can get all the old grease off it.
The shape and design of the exhaust port looks like the 70 cc models, I think you will find your measurement on the bore is closer to 2.00 if you can measure it more accurately.
Mark
Mark
fechtichmac
ArboristSite Operative
My cp70
Version without decomp.valve.
LH - Start .354 chain
E.
Gesendet von meinem SM-G955F mit Tapatalk
Well, ill be darned!! Thats awesome. Yet another 70cc variant. One thing about mcculloch, they were consistent!! LolMy cp70
Version without decomp.valve.
LH - Start .354 chain
E.
Gesendet von meinem SM-G955F mit Tapatalk
Yokosukadweller
ArboristSite Member
Thanks for sharing the photo of your nice looking cp70 version. I tihink it could be the version I got, except mine did have the red decompression button - but just not that oldschool lever. So many versions...they must have really experimented or...just put together saws with lots of small variations due to whatever was available at the time or wot?My cp70
Version without decomp.valve.
LH - Start .354 chain
E.
Gesendet von meinem SM-G955F mit Tapatalk
Is it hard to start without decomp? I guess you just need to time the pull...
Is the engine block of your saw painted? I couldn't see it from the pictures..
@heimannm regarding the measurement of displacement you're probably right my use of the straw to measure was likely a bit off...but still - the serial is just wrong then, could be several reasons for that I guess...
fechtichmac
ArboristSite Operative
Yes , block is painted , and has the plugged hole ,where the lever style decomp. normally gets in. Yes , it is a little hard to start.
May be yours is a replacement sp 70 block.
because it has the " newer style" decomp.
Gesendet von meinem SM-G955F mit Tapatalk
Good stuff. Thanks for taking the time to share. Does it have a tag?
My cp70
Version without decomp.valve.
LH - Start .354 chain
E.
Gesendet von meinem SM-G955F mit Tapatalk
I've never seen that rubber grip on the rear handle before. Nice saw i really like that
Yeah I wouldn't always trust the tag. The tag in my opinion goes in with the other evidence on the evidence wall and helps to build a picture of what it is. On a clean unmolested saw ya can take it for the truth but only with the other evidence.
Its just too easy to replace a broken part.
I have 4 7-10s and only 1 has a tag the others have either been lost during a rebuild or as I suspect due to paint tone variations have had new tanks. 3 have unpainted cylinders and I'm still on the fence if thats gospel or not.
The thing is they are great saws and all mixed up bits or not will cut your firewood for years n years n years n years.. ... then your kids or someone else's.
Once you get a little collection going you can pretty much keep 1 or a bunch running till you croak lol.
I got 4 7-10s with 3 good cylinders
I got 3 700s two really nice ones and a spare 700 engine. That should see me and my boy out for a runner 70cc rigid 10 series for the next century
A av 70 of some description would be darn nice though and hmmm with some bits can build 1
Great old saws
