MCCULLOCH The official McCulloch thread

[Al Smith]

Mac# 83859 --Cr 4913---https://www.motionindustries.com/productDetail.jsp?sku=01321111

 

[nbbt]

thanks

Mac# 83859 --Cr 4913---https://www.motionindustries.com/productDetail.jsp?sku=01321111

 

[Al Smith]

FWIW I have the master interchange book for CR/SKF seals .I can find most of the them but not all of them .Some times on things like Stihl for example Google can find some of them but not all of them .

 

[Simpsonsawshop]

So the SP81 is up and running and oiling great. Thanks @Steve . I dont think I have the tuning right. It seems to be running well but it just seems slow. I started at 1 1/2 turns out on the hi jet and I think I am in to about 1 turn to get here. Should I lean on it a bit more? I just dont want to burn it up. 28 inch bar, stock chain off the roll 3/8
.050 full chisel.

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[Dream]

Your low side sounds really good. Maybe just small tweaks in on the high side till it still burbles a bit, but still cleans up in the wood. Seems like its a bit sluggish under load. Hows the compression and seals etc?
My PM700 has more bawls. Sounds like she might just be too rich on the high side.
If you have good compression and have checked for any leaks, go ahead and lean out a bit. Just make sure you keep her 4 stroking a bit out of the cut. Small steps.

 

[Bigmac]

So the SP81 is up and running and oiling great. Thanks @Steve . I dont think I have the tuning right. It seems to be running well but it just seems slow. I started at 1 1/2 turns out on the hi jet and I think I am in to about 1 turn to get here. Should I lean on it a bit more? I just dont want to burn it up. 28 inch bar, stock chain off the roll 3/8
.050 full chisel.

Sent from my SM-G950U using Tapatalk

It’s kinda hard to tell the tune without a full throttle piss rev, it didn’t sound blubber rich so it’s hard to say. Have you checked your points gap? What’s the compression at? Dose it four stroke?

 

[Simpsonsawshop]

It’s kinda hard to tell the tune without a full throttle piss rev, it didn’t sound blubber rich so it’s hard to say. Have you checked your points gap? What’s the compression at? Dose it four stroke?

When I took the video I didnt really intend to ask about tuning lol, that was an afterthought. This saw came to me as a runner, I did a partial teardown to repair some known issues. Pressure and vac tests pass, have not had a compression gauge on it but I cant pull it without the compression release. I have not messed with the points at all, I did think of that, maybe the gap is too tight and the timing is retarded.

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[Bigmac]

I would check the points, if it has tightened up it would make it lazy, and you might get a couple of degrees of timing by maxing them out. I have an sp81 that has 175 lb of comp and an sp80, with a replacement cylinder, so it’s an 81 basically, and it has 155 comp, the 81 and the decomp are a must! The 80 is startable without decomp but it’s nicer with. And there are guys that have 200 psi 82cc macs, for some reason the comp can be all over the place, I am going to guess that if the comp is low it will feel lacking, my 80 is going to get a full tear down, and will likely get new rings to see if the comp bumps up

 

[Al Smith]

For some reason McCullochs need to run a tad bit rich but not to the point of loading up .I'm not exactly certain why .

 

[Bigmac]

For some reason McCullochs need to run a tad bit rich but not to the point of loading up .I'm not exactly certain why .

I agree al, I think it’s because of the very free flowing mufflers!

 

[Al Smith]

That probably has something to do with .The few 10 series I've measured already had the exhaust port opening at 96 after plus in retrospect the transfers seem to be larger than most saws .So it might be such a thing it's blowing out a lot of fuel until the port time area open becomes less as the speed increases .
On the saw in question it would be easy to figure out.Just tweak it in the cut or rather as cutting with it .

 

[Bigmac]

That probably has something to do with .The few 10 series I've measured already had the exhaust port opening at 96 after plus in retrospect the transfers seem to be larger than most saws .So it might be such a thing it's blowing out a lot of fuel until the port time area open becomes less as the speed increases .
On the saw in question it would be easy to figure out.Just tweak it in the cut or rather as cutting with it .

Agreed Al! Am sure that’s part of it too. My kart Mac likes it on the edge of too rich too, I was messing with it in the wood, and leaned it so it would just clean up in the wood and that’s were it had the most torque in the cut.

 

[Dream]

Sounds like you need to verify where the points are, then tweak the tuning on the high side til it gets to the sweet spot.
My PM700 is solid state ign. I had to go thru the carb because I fed it some bad fuel. Just got it out at the log pile and tweaked til it ran right. It pulls hard. Always has. Good torque. I wonder if it's got anything to do with the ignition timing? Its all bone stock. Ive always wanted to make an adjustable coil mounting plate versus machining off the flywheel key. Would be way easier to make minor adjustments without having to pull the flywheel, once you got the machinework done to mount the coil.

 

[Al Smith]

Since it's been mentioned one old engine did use a rotor plate,AH58 Power Products . In that example both the coil plus the points rotated which it theory would put the timing in phase with the hot spot of the coil .That is a window where the max lines of magnetic flux are cut producing the hottest spark .Even with that set up it was set at 26-27 degrees advance .

 

[Maintenance Chief]

Sounds like you need to verify where the points are, then tweak the tuning on the high side til it gets to the sweet spot.
My PM700 is solid state ign. I had to go thru the carb because I fed it some bad fuel. Just got it out at the log pile and tweaked til it ran right. It pulls hard. Always has. Good torque. I wonder if it's got anything to do with the ignition timing? Its all bone stock. Ive always wanted to make an adjustable coil mounting plate versus machining off the flywheel key. Would be way easier to make minor adjustments without having to pull the flywheel, once you got the machinework done to mount the coil.

On a solid state ignition coil it might be easier too open up the holes in the lamination and tweak the timing that way.
I have had a few that I bought that the coil was loose for who knows how long and the holes were worn and allowed for additional timing up and down.

 

[Al Smith]

You can get into a guessing game on really tweeting an engine .It's been said the higher the compression the less advance it needs .An example of same is when they came out with "low lead " gasoline .Prior to that a Ford 460 was some amazing HP but after with a lower comp the timing had to be advanced because the burn rate of the fuel was slower.In other words they had to light the fire sooner .
Then comes the problem,exactly how do you determine that .I don't think they make a timing light that would respond that fast on a reved out two cycle .So then it's trial and error .Sure you can statically time them but under dynamic conditions it might not work so well .

 

[heimannm]

Non saw McCulloch day today. I am just cleaning these up in order to put them on display in the museum but I do like to make them "run able" if it is possible. Both will run on a prime, I expect the blower would run with fuel in the tank but I didn't want to fuel it up just to drain it out again. I had another just like it yesterday that I will keep in running condition at the museum for outdoor clean up. The Aqua Mac is missing the fuel tank and some hardware to attach it to the pump as well as the air filter and cover.





The carburetor on the Aqua Mac is somewhat unique.







Mark

 

[heimannm]

After putting together a blower for myself yesterday from the box of parts in the attic, and cleaning up another to put up in the museum, a package arrived today (thanks again to Maintenance Chief).











Mark

 

[heimannm]

I do like to be somewhat thorough in my clean up of these projects before I move them over.











Mark

 

[heimannm]

A few more.











Mark