McCulloch Chain Saws

[Maintenance supervisor]

Here's a D009 that cost me 50$ on Amazon, can you imagine what a 36" sprocket nose Homelite bar would have cost?

 

[Brownthumb]

My air filter is good. I just cant get her dialed in.
I went over carb and she has new everything down to the nozzle using factory kits, I rebuilt her twice checking my work. New crank seals, no leaks.
Its just slow to accelerate, off of idle it is just slow per say not Zippy.

 

[northwest saws]

Tore the cylinder and piston off the model 73. Cylinder is pretty good but the piston is toast. It's cracked in two places on intake side. Anyone know a fella who might have one laying around?

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[BroncoRN]

Joey helped me figure it out. Spark plug was crap - at least so far. I know I need gasket between carb and air box. And then fiddle with tuning.

 

[joeymt33]

Joey helped me figure it out. Spark plug was crap - at least so far. I know I need gasket between carb and air box. And then fiddle with tuning.

Good luck bud.

 

[Todd Loosli]

https://www.ebay.com/itm/143524510485

 

[vinnywv]

Anyone ever seen a red mac? My buddy wanted me to ask. It was given to him. Eager beaver 2.1. But its red. Its not paint either. The plastic is red.

 

[wcorey]

Ok,

In the interest of the 70 cc ten series cause I stripped my latest Pro Mac 700 acquisition and port timed it.

This saw looks to have never been tampered with, its a 600061B, carb dated 1-79. Thin ring, divided transfer, unbridged exhaust, and in good shape. I will picture it once I run it through my works washing plant next week. Its a right manky thing, despite already been cleaned as best you can intact.

Exhaust opens 100' ATDC - 160' duration.

Transfer opens 117' ATDC giving 17' blow down.

Intake opens 61' BTDC - 122' duration.

As I mentioned earlier, the exhaust / transfer timings are similar to more modern designs. The intake duration is short compared to modern designs. This likely explains the high torque / low rpm characteristic of the 700.

Lets see if we can find some more data - afraid I don't have a 7-10. Mean time I will give some thought about modification. The short intake is an issue. I suspect the exhaust, whist not short on noise, is short on optimal performance. I am prepared to loose some torque at low RPM to pick up some more RPM BHP on this saw. I don't want to turn it to a peaky boggy saw, or end up with excessive reversal on intake - spit back - by over doing intake duration.

Roland.

Haven't been keeping up here of late, just did some long overdue getting up to date reading so a little late to the party as usual...

Happened to have a "two top label" divided transfer 7-10 apart so did the numbers, almost exactly the same as this pm700, maybe one less degree of intake.
Squish was a little odd in that it's reverse tapered up toward the cylinder wall. So .035" at the combustion chamber and .055" at the cylinder wall.
Looks to be a good candidate for a welded popup and a few mm off the intake side piston skirt...

 

[northwest saws]

[QUOTE="Todd Loosli, post: [/QUOTE]

I saw that. Going to be patient and wait until something fair to come along. Some decent damage to that cylinder roof, damage to piston and no rings.

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[Maintenance supervisor]

My air filter is good. I just cant get her dialed in.
I went over carb and she has new everything down to the nozzle using factory kits, I rebuilt her twice checking my work. New crank seals, no leaks.
Its just slow to accelerate, off of idle it is just slow per say not Zippy.

Do you have another carburetor, as with anything else old it could have the needle tapered holes wore too big from forcing them down to hard . Aluminum vs steel the needle will usually win. I'm not being a jerk but are the needles in the correct holes? It happens.

 

[Jethro 2t sniffer]

Haven't been keeping up here of late, just did some long overdue getting up to date reading so a little late to the party as usual...

Happened to have a "two top label" divided transfer 7-10 apart so did the numbers, almost exactly the same as this pm700, maybe one less degree of intake.
Squish was a little odd in that it's reverse tapered up toward the cylinder wall. So .035" at the combustion chamber and .055" at the cylinder wall.
Looks to be a good candidate for a welded popup and a few mm off the intake side piston skirt...

Would like to know more about this. A basic performance recipe even? To atleast copy the big transfer 7-10 power

 

[Ben79]

I managed to get this Pro Mac 55 back together and running over Easter. It runs really strong. Yet to put it in wood, hopefully soon! I really enjoyed working on this one!

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[2broke2ride]

Well, I caved and bought it. Now I wait. This is the second saw I've bought from this seller so I know the shipping will be slow. The last one turned out to be a 5-10! Hoping this one is a 6-10. The anticipation is gonna kill me lol.

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Tracking says this will be on my doorstep when I get home tonight! Apparently these folks have stepped up their shipping. The anticipation is killing me lol.

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[RolandM]

Haven't been keeping up here of late, just did some long overdue getting up to date reading so a little late to the party as usual...

Happened to have a "two top label" divided transfer 7-10 apart so did the numbers, almost exactly the same as this pm700, maybe one less degree of intake.
Squish was a little odd in that it's reverse tapered up toward the cylinder wall. So .035" at the combustion chamber and .055" at the cylinder wall.
Looks to be a good candidate for a welded popup and a few mm off the intake side piston skirt...

Thanks for taking the time to find the timing numbers for your 7-10, interesting to see that they are the same as the pro Mac 700 of mine. So aside from iron cylinder saws which are unknown , we have identified similar port timings of 7-10 and pm 700 chrome bore cylinder saws, and then the super pro 70 chrome cylinder which has quite different timing.

I agree the recipe for higher rpm power output is going to be based on extension of intake duration and possibly compression. I would also smooth and tidy both intake and exhaust tracts, but on my saw I will not grind into the chrome plating on the cylinder bore to port radii for durability concern, so factory exhaust and transfer timings will remain.

I suspect as mentioned before, the exhaust, whist not short on noise is not brilliant and I have ideas. However with current work load, I am not sure when I will tackle this or porting the saw, but its high on the agenda. Will keep you all posted as it progresses. Mean time more data the better on timing etc, especially saws with run better or worse than others.

Roland.

 

[2broke2ride]

These numbers mean anything to anyone? Trying to figure out what I just bought without pulling the muffler. Might have to though lol.

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[Brownthumb]

No I don’t have another carb the kits came with new needles. you can’t mix the needles up but then again I have seen a lot of things in my day.
Some times too much gas then not enough like a impulse leak or clog.
Might as well drop skirt off and have a look.

 

[Jethro 2t sniffer]

Thanks for taking the time to find the timing numbers for your 7-10, interesting to see that they are the same as the pro Mac 700 of mine. So aside from iron cylinder saws which are unknown , we have identified similar port timings of 7-10 and pm 700 chrome bore cylinder saws, and then the super pro 70 chrome cylinder which has quite different timing.

I agree the recipe for higher rpm power output is going to be based on extension of intake duration and possibly compression. I would also smooth and tidy both intake and exhaust tracts, but on my saw I will not grind into the chrome plating on the cylinder bore to port radii for durability concern, so factory exhaust and transfer timings will remain.

I suspect as mentioned before, the exhaust, whist not short on noise is not brilliant and I have ideas. However with current work load, I am not sure when I will tackle this or porting the saw, but its high on the agenda. Will keep you all posted as it progresses. Mean time more data the better on timing etc, especially saws with run better or worse than others.

Roland.

Be really cool if we could get a list together of all of these numbers. I will be rebuilding a 7-10 divided transfer at some point in the future and also have a 700 engine to go back together. This is exciting stuff

 

[Jethro 2t sniffer]

These numbers mean anything to anyone? Trying to figure out what I just bought without pulling the muffler. Might have to though lol.

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More pictures 2broke

 

[2broke2ride]

More pictures 2broke

In a bit. It's another 70cc, measured the bore. First 10 series I've seen without an auto oiler. Wicked compression and fires on prime.

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[2broke2ride]

Has paint fade and some minor mag rot on the blower housing and lower handlebar mount but it should make a decent runner.
I'm assuming it's a 6-10. Need someone better schooled than me to chime in.
@heimannm

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