McCulloch pro mac 700 rebuild thread

[brandonstc6]

My first saw was a pro mac 10-10s, which I still have. I have always wanted a pro mac 700 and ended up buying one for $15. The guy said he used the saw a lot but it kept getting harder to start and eventually wouldnt run and he said he thought it needed carburetor work. I got the saw home and it had low compression. I pulled the muffler and carburetor off and the piston and cylinder looks good so i ordered a set of rings. My bearings seemed fine but i got a good deal in new ones on eBay so i bought them. I took the saw completely apart and cleaned and re-painted the oil tank. I know i am going to have several questions along the way so i decided to do a build thread.

I painted my oil tank with rustoleum john deere yellow. It is a close match but not perfect.

My recoil starter had a busted dust shield but i had a good one from a parts saw.
I popped out my old crank seals. They had gotten pretty stiff from age and I will be getting new ones from a hydraulic supply shop or a bearing shop.

I took the piston and rod off the crank. When i took it off, i didn't pay attention to which was it was on but I'm assuming the ex marking points towards the exhaust. I put the rod and needles back on the crank. I can't see anything wrong with the needles, connecting rod, or crank. However the connecting rod seems to have too much "Play" in it. I took a video to show you guys. Does this mean the needles are wore out? Is the rod wore out or what?

 

[svk]

Subbed.

Can you get that video uploaded to YouTube so it's easier to open?

 

[brandonstc6]

Here is a YouTube link to the video. It should be easier to view now.


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[astnmacgto]

My biggest concern would not so much be side to side wiggle but whether or not it's loose with a push towards the crank and pull on the rod away from the crank, like if it were running...... but I could be totally wrong, someone with lots of experience will correct me I hope

 

[alexcagle]

Wow.
That's unacceptable play alright.
Not trying to be a smartarss, but are you sure you didn't drop a roller or two?
Is the rod elongated?
Do you have any of those other parts saws with a crank with less play?
That much play will hammer the rod cap bolts right off.
There should be zero up and down play. Side to side play is not so critical

 

[alexcagle]

My first saw was a pro mac 10-10s, which I still have. I have always wanted a pro mac 700 and ended up buying one for $15. The guy said he used the saw a lot but it kept getting harder to start and eventually wouldnt run and he said he thought it needed carburetor work. I got the saw home and it had low compression. I pulled the muffler and carburetor off and the piston and cylinder looks good so i ordered a set of rings. My bearings seemed fine but i got a good deal in new ones on eBay so i bought them. I took the saw completely apart and cleaned and re-painted the oil tank. I know i am going to have several questions along the way so i decided to do a build thread.View attachment 542699

I painted my oil tank with rustoleum john deere yellow. It is a close match but not perfect. View attachment 542700

My recoil starter had a busted dust shield but i had a good one from a parts saw. View attachment 542701
I popped out my old crank seals. They had gotten pretty stiff from age and I will be getting new ones from a hydraulic supply shop or a bearing shop. View attachment 542703

I took the piston and rod off the crank. When i took it off, i didn't pay attention to which was it was on but I'm assuming the ex marking points towards the exhaust. I put the rod and needles back on the crank. I can't see anything wrong with the needles, connecting rod, or crank. However the connecting rod seems to have too much "Play" in it. I took a video to show you guys. Does this mean the needles are wore out? Is the rod wore out or what?

*
Is it just me, or did get yellow paint overspray on your camera lense too?

The pics all have a yellow tint.

 

[brandonstc6]

Wow.
That's unacceptable play alright.
Not trying to be a smartarss, but are you sure you didn't drop a roller or two?
Is the rod elongated?
Do you have any of those other parts saws with a crank with less play?
That much play will hammer the rod cap bolts right off.
There should be zero up and down play. Side to side play is not so critical

The rod had that much play in it before I took it off the crank. All the rollers were there. I have a pro Mac 10-10 in a box that should have a good crank and rod, I will try that and see if it has as much play. Should I replace the needles? I don't have all the 10-10 needles because I stole some for a universal joint. I do have all the 700 needles.
Also the light in my shop emit a yellow light, thus making all the pictures have a yellow tint


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[alexcagle]

Just as long as they look good and you end up with no "play". Otherwise you may need new rollers.

 

[brandonstc6]

I'll check it out and see what I can come up with


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[brandonstc6]

I tried the pro Mac 10-10 rod and crank with the pm 700 bearings and it made no difference. How can I tell what's wrong? Will a pm610 crank work?


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[brandonstc6]

I'm going to take apart my mcculloch pro Mac 610 that has a busted oil tank and see if the rod has that much "play" and use those needles and rod on my crank and see how much "play" it has


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[astnmacgto]

Speaking of pm610 and 10 series needle bearings, does anybody know if the needle set for the 610 is the same needle set for all the 10 series stuff

 

[brandonstc6]

I took apart a pro Mac 610 and it has the same "play" in the rod. Does anyone know what is going on?
Here is another video.



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[heimannm]

Needles are the same on most of the 10 Series and 600 Series, the PM8200/PM5700 may be different since everything else is different on those models.

I will disagree with alexscagle here, check for play in the direction the rod actually works (radially only), as astnmacgto suggests. I think you will find there is no unwanted movement where it actually counts. Most any saw with loose needles like the McCulloch's use will have a fair amount of play in "non critical" directions. In the saw the parts don't move like that since the piston and wrist pin keep things in line. I went up in the attic and dug through boxes to find a crankshaft and connecting rod and it moves just like your video. I have seen that on several saws as I was rebuilding them as well.

The kart guys would leave one or two rollers out of the big frame engines to give them a bit more freedom of movement and those engines really turned some rev's.

Mark

 

[brandonstc6]

Needles are the same on most of the 10 Series and 600 Series, the PM8200/PM5700 may be different since everything else is different on those models.

I will disagree with alexscagle here, check for play in the direction the rod actually works (radially only), as astnmacgto suggests. I think you will find there is no unwanted movement where it actually counts. Most any saw with loose needles like the McCulloch's use will have a fair amount of play in "non critical" directions. In the saw the parts don't move like that since the piston and wrist pin keep things in line. I went up in the attic and dug through boxes to find a crankshaft and connecting rod and it moves just like your video. I have seen that on several saws as I was rebuilding them as well.

The kart guys would leave one or two rollers out of the big frame engines to give them a bit more freedom of movement and those engines really turned some rev's.

Mark

That's great news to hear. Thanks so much for the information. I didn't find any vertical play in the connecting rod, so I will continue with my build.
That's interesting on the kart motor builds. I've never had any experience with this type of crankshaft with the needles.
Thanks! I really appreciate it.
Brandon



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[Justsaws]

When you are checking for play in the big end bearing try to mount it in a vise or lathe, something heavy and rigid. Then pull and push in line with the rod, rotate an 1/8 turn of the crank and pull and pull, continue all the way around. No need to push/pull very hard however it can be easier to detect the movement when mounted in a rigid device. If
You want to be sure than the piston and it's bits need to be removed, do not do remove unless you absolutely have to. Check the crank needles for wear on the tips, or damage/wear to the middle area. Lay needles out on a white piece of paper after cleaning to inspect and measure. Usually need a magnifying lense to do this myself, tiny little buggers.

All things considered it was a fairly bullet proof design. Most that I have replaced were damaged by water or lack of lube.

They are pretty loose side to side, apparently that is where the speed is. Just make sure the rod and crank bearing surfaces are square and smooth and that the needles are undamaged and uniform as a group.

Unless you think you feel a problem with the push/pull I would not remove the piston. I would put this in bold if this device I am typing on worked. Do not remove piston unless you absolutely have to and have replacement parts in hand.

 

[blsnelling]

I agree with Mark. ALL rods will have side to side and angular play. The only thing you need to check is radial play.

 

[brandonstc6]

I agree with Mark. ALL rods will have side to side and angular play. The only thing you need to check is radial play.

Thanks for the advice. I do not have any radial play so I am going to continue with my build and use what I have. Right now I am soaking my piston to dissolve what carbon didn't come out by scraping the ring grooves.


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[blsnelling]

I use a piece of the old ring to clean the grooves and a wire wheel on the crown.

 

[brandonstc6]

I broke one of the old rings and cleaned out the carbon. I then put the rod and bearings on the crank

I then put the rings on the piston

Then I put a thin layer or motoseal on the oil tank and put the cylinder on

Now tomorrow I'm going to a hydraulic supplier or a bearing supplier to get some crank seals
Thanks for the help you guys.
The build continues


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