Pro Mac 850 project

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Also, what do I use for an exhaust gasket? Will cork/rubber work or is that gonna just catch on fire and burn?
 
The 8 pin 3/8" sprocket is in the mail. Ron

promac610, this thread http://www.arboristsite.com/chainsaw/166543.htm got me thinking so I went back through my IPLs on the 82cc MACs. They all list a 7 pin .375 sprocket as the standard sprocket. I have sent you every sprocket I have so I figured (wrongly) that the 8 pin was standard for 3/8" on these saws. I haven't done the math yet but I doubt there is much difference in chain speed between a 7 pin .404 and a 8 pin 3/8. Anyway just wanted to let you know that apparently I don't have the "correct" sprocket to send you. Ron
 
promac610, this thread http://www.arboristsite.com/chainsaw/166543.htm got me thinking so I went back through my IPLs on the 82cc MACs. They all list a 7 pin .375 sprocket as the standard sprocket. I have sent you every sprocket I have so I figured (wrongly) that the 8 pin was standard for 3/8" on these saws. I haven't done the math yet but I doubt there is much difference in chain speed between a 7 pin .404 and a 8 pin 3/8. Anyway just wanted to let you know that apparently I don't have the "correct" sprocket to send you. Ron

That's okay, I bet it'll cut plenty fast with 3/8" 8 pin. The speed difference won't be much, but the biggest benefit is how I'll be able to swap bars and chains between the Macs if I need to. :cheers: It will cut, and I bet it'll be one of the fastest big wood saws around my neighborhood. :)
 
Thanks for the link! :cheers:

I forgot about copper sheeting, HD near me sells that. I'll have to go pick a sheet up. :)

I did some research on copper and aluminum, and it is a bad idea to put the two together, galvanic reaction will occur.
Here's the article... Never Mix Metals Copper Aluminum Flashings

So, I will be ordering a gasket soon.

Edit: did more research, and found that a sheet of aluminum cut as a gasket will work. Might pick one up soon.
 
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Alright, bet you all have been waiting for pics...

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This part was the fun part... I had to fix the screwed hole made by someone somewhere in Brazil or something... :D

Alright, what I did was take a nut that was 10-24 thread and reduced the outside diameter and also purposely didn't make it round. You can see why in the pic, it'll help keep the nut from spinning in the bore.

I made the already screwed hole bigger, a little at a time to make sure that the nut was a press fit. Tapped the nut, which is now a thread insert, into the bore with a hammer and then staked it into place. It looks promising, and as long as Murphy don't show up, it'll work. :)

I saved money, and put the Dremel to work with a tungsten carbide cutter. Best 8 bucks I ever spent, it cuts real smooth and defintetely makes quick work of both aluminum and steel.

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More in the next few posts. :blob2:
 
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Got some more... :)

Base of cylinder... looks good to me.

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Screw hole, before...

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Screw hole, after...

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Pretty cool, huh? If you noticed, I had to remove material on the left side of the hole, as to make sure the center of the insert would line up with the hole in the muffler case. I mocked it up when I was done, and it was perfect. Nothing like doing something yourself, and it's also really nice to do it right. :)
 
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Depends on how you define "neighborhood" :hmm3grin2orange:.

I doubt anyone in the houses near me have a saw this big. :) My neighbor has two tiny Homelites, one old iron, one new HD plastic. Both are nice saws. (opened another can of worms...)

Your solution is very clever. Good work.

someone somewhere in Brazil aka Ron

Thanks, it took me a little thinking, but hey, I saved gas too! :) I bought the Dremel bit on one of my previous trips to HD.
As for :poke: fun at ya, I had to. You're pretty squishy. :biggrinbounce2:
 
Did you pressure test the engine?

pressure test that baby with some fuel mix!!!!:chainsawguy:

I did that standard hang it by the recoil handle test. It stayed put for a long time, a really long time. As for pressure testing the case, no I haven't. My air compressor isn't wired up yet.

As for starting it, I don't think the neighbors would like that on a school night. I don't even have fuel mixed up for it yet.

I already :msp_wub: this saw...

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She will run tomorrow. (knock on wood, I do not want Murphy to drop by...) Vid hopefully will be done tomorrow also. I think I will throw the B&C that's on the 610 on this for some test cuts. Nothing real huge around here though, except the neighbor's tree... uh oh, I'm getting a bad idea... :D Maybe I'll go to the back of the property and make test cuts on that slightly rotted out tree trunk I dropped a while back. Bring the camera and a little tripod. I'll be pissed if I forgot those, it's quite a long walk back there...
 
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Did I short you a recoil cover screw or did you forget one? I don't know who V.H. of Idaho is but I hope you have made him proud. Ron

Yeah, the recoil cover screw, one of those really long screws, and bar nuts. The other missing hardware was replaced by what I found in my ridiculous stockpile of misc. fasterers and crap. I found one nut that fit on the threads, but do not plan to use it for a bar nut permanently as there is no flange on the nut. I will know for sure once I clean off my workbench, lol. It's a mess.

When I make the test cuts, I can use the bar nuts off my 610, I believe they're the same size and thread.

I noticed the V.H. scratched into the cover too, I hope I made him/her happy as well. I'm already :msp_drool: over what I think this thing will sound like. :)

BTW, does anyone have a recommendation as a starting point of carb tuning? Where should the H/L screws be set at? Also, which way is richening and leaning the air/fuel mix?

Also, your rim sprockets and the recoil cover are in the mail.
 
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