McCulloch 4600 restoration

[Arrmon Lute]

Hello folks, I'm new to the forum. I just picked up an old MAC/McCulloch 4600 for cheap off of craigslist. It doesn't run but it did have decent compression when I pulled the cord. I have some pictures from the ad on craigslist, I'll get some pictures of the saw all taken apart on my workbench in a minute.

When I first got it the pull starter didn't pull the rope back well the first few times, then at all. I took it apart, cleaned all the sticky grime off of it, and reassembled it. I found that the actual problem is a large crack going radially in about 3/4 inch and then a right angle to go about 1.5 inches in a smaller concentric circle in the pulley. This allows the rope to "double stack" or stack side by side, this wedges the pulley wider and jams one the small wings that engages the flywheel. With the wing stuck out it interferes with the flywheel and has to be pulled from the saw to be wound properly. I'm going to try some JB weld tonight before I order a new pulley

Since I cannot really get a good pull on the saw I haven't been able to test the ignition

The chain was moving really funny when I tried to sharpen it, I took the side cover off and found two things. First, the sprocket had a really nice deep groove in it, so I'm going to need a new one of those. Secondly, the chain brake band is broke right in two! I actually cannot find a replacement on of those, if someone has one or knows where to get one please PM me.

Oh, and I also cannot find a clutch removal tool online, does another manufacturers tool fit?

ALL the plastic lines are rock hard and shot, I might need to remove the engine from the frame to replace some of them. Oddly the primer bulb seems to be just fine!

I'm going to go get some more pictures to look at, if anyone know where to find these parts or has them please shoot me a PM.
-Chain brake band
-8 tooth .325 pitch sprocket/drum
-Clutch tool
-All parts are for a McCulloch 46

 

[Arrmon Lute]

Well, I forgot to bring my SD card. But I did do some other work and got a lot done.

I cleaned the engine up, saw the plug was running lean and decided to take a further look into it. I took the engine all apart, cleaned it up in mineral spirits.

I found a new side cover with a functioning chain brake for $20, score! I ordered a new sprocket and piston ring on ebay, and I plastic welded up the broken recoil pulley.

I also assembled the engine without the ring, fabbed up a degree wheel and a piston stop and got my timing specs.
I'm looking at exhaust starting at 107* ATDC with a duration of 136 degrees, intake starting at 73* BTDC with a duration of 146*. Transfers open at 129* ATDC with a duration of 105* for a blowdown of 22*.

This seems to have a few odd things, one an intake duration longer than exhaust, and a short blowdown.

I raised the squish from .052 to .022. I'm going to use this for a work saw in various hardwoods, so I would like to lengthen the blowdown for more lugging power but I'm not quite sure how to do that without raising the exhaust and decreasing my power stroke...

Oh, and i found that a 12 point 16mm socket works excellent to remove the clutch.

 

[Chris-PA]

I'm going to guess that there won't be much enthusiasm in that saw from too many members. I have found them interesting (especially the 55cc version) but never ended up getting one.

An intake duration longer than the exhaust duration is typical. The duration numbers are pretty short in my opinion, but I am not too experienced. If it were mine I would lengthen both, but the problem I always have is in raising the transfers since I don't have a right angle grinder.

 

[Wagnerwerks]

I parted one of these out a while back. I know parts were hard to find as the folks that bought mine were happy to have them. I'll be watching this. I like a good fix a not so common saw thread.

 

[Arrmon Lute]

Well I got my pictures!
That is mostly engine pics, you can see where I did the plastic weld on the rope pulley in the last one.

I did do a little bit of porting. I widened the transfers at the base of the cylinder so the gas had a properly stepped path from the crankcase. Since I decided not to mess with timing numbers until I see how the saw runs I just widened the intake port by .100 across both sides and beveled the edges, I did the same thing to the exhaust except I removed .250 across the entire port. The thing is, there is still much more material to remove before I get close to the edge of the piston skirt on the exhaust side! I just want to reinforce the outside of the port with some 1000* epoxy before I go any further.

I should have my new sprocket today, just waiting on a piston ring from romania

I honestly can't wait to have a better backup saw, my Stihl 025 AV started running like crap on Sunday and I had to use my Poulan Pro!

 

[Chris-PA]

I bet that engine runs fine. I'm not sure I'd want to rely on epoxy - an additional 0.25" in port width is significant, so I'd probably stop there if I was getting close to the limits.

 

[Arrmon Lute]

Honestly, I'm not even close to the port limits. And if your willing to pay for it, you can get some marvelous epoxies! They really are impressive if you buy the machinable grade stuff. I usually use Devcon when bedding rifles because it has damn near no swell under indoor and outdoor temperature ranges. I will try to find some high temp though.

I don't have a ring compressor small enough for this engine, I was thinking about welding one end of a piece of thin sheet metal inside of a hose clamp, think it would work?

 

[Jeff Lary]

Nice work, I was wondering if you had a plastic welder or if you used a torch / screwdriver or how you did it?

 

[Arrmon Lute]

I have a plastic welder, I bought it at harbor freight and upgraded the air regulator. it works pretty well. My only real complaint is that the plastic filler rods do not separate, when you are melting a rod into a seam/bead you need to have some form of mechanical force applied to the filler rod to separate the heated tip from the unheated heated rod. I am going to try a smaller rod to see if it will drip in two. It's that or weld a nail or something to the tip of my plastic welder.

 

[Wagnerwerks]

I have that same plastic welder. It works pretty well. I use it for auto body panels and household broken items and it's paid for itself so many times!

 

[Jeff Lary]

well it looks real good. now..... off to H.F.

 

[Chris-PA]

Honestly, I'm not even close to the port limits. And if your willing to pay for it, you can get some marvelous epoxies! They really are impressive if you buy the machinable grade stuff. I usually use Devcon when bedding rifles because it has damn near no swell under indoor and outdoor temperature ranges. I will try to find some high temp though.

I don't have a ring compressor small enough for this engine, I was thinking about welding one end of a piece of thin sheet metal inside of a hose clamp, think it would work?

I've actually never used a ring compressor on a saw - I just use my fingers.

 

[Jeff Lary]

on E Bay they sell a kit not too much money less than 10 bucks I think. Type in piston ring tool or whatever gets you there into google or e-bay . You are looking for a small red 5 or 6 piece kit . It comes in a cheep see through plastic bag / case. You will get 4 c shaped collapsers (sp) a bridge to hold the piston in place and a whit plastic piston stop. I use mine all the time

 

[rmh3481]

You can make yourself a ring compressor out of a strip of two litre pop bottle. When you cut the strip out of the plastic bottle make sure its long enough to grab with your thumbs.

 

[Arrmon Lute]

Yeah, make sure to get the model with an adjustable temp setting and air regulator. I think I paid $80 for the welder, better regulator, and filler rods. I know I've made a bunch of money repairing customers plastic trim/fairings with it, and saved them from stealership prices!

I cleaned the exhaust port with steel wool wrapped around an auger bit, applied the High temp epoxy to the floor, let it cure halfway and removed the bulk of the epoxy to give it a flat floor in the port. I'm going to take the cylinder to work today and use a scribe to get a good idea of how far I can port it. I plan on giving myself 2mm from the skirt edge on the intake and exhaust. I got my NOS sprocket and clutch drum in yesterday, this thing looks amazing! I have some Oregon chain and tygon fuel line+ extras on order as well.

Thanks for the pop bottle tip, I'll try that before I weld something up. The MIG welder at work isn't exactly the greatest and I don't feel like going to my machine shop in Hazel park just to TIG the thing up.

 

[Arrmon Lute]

Ok, I got my piston ring in from freaking Romania! I got the engine back together, put on a new oregon chain, new tygon lines, added a filter to the primer bulb. A brief assembly and I couldn't get her to fire up...I decided to screw the carb screws all the way in and start tuning from scratch. The low screw was about 5 turns out! I got the low set up decent, ended up having to restart it a few times as I worked on it and the idle speed screw. WOT is kinda lean but not too bad. Problem being that I should have finished the plastic welding job I started, the entire side of the pulley broke off after several starts. I'm just going to order a new one and not worry about micro-fractures I missed growing bigger and causing problems.

 

[Chris-PA]

Frustrating when one piece holds it up! I still bet that thing runs pretty well when you get it going.

 

[Wagnerwerks]

Hazle park? Where are you from?

 

[Arrmon Lute]

I live in the West Bloomfield/Commerce area. Yeah I had it running for about 10 minutes, it sounded great! I have never tuned a two stroke before so I'm doing some reading as to how this goes.

 

[LegDeLimber]

Not sure if I'm reading correctly here.
Is the epoxy in direct contact with the exhaust gases of the running motor?
If so I'd wager a few before and after style pics would be of interest to folks here.
I've had Devcon stay in service for decades on an Echo gas tank/metal (cs302, non bladder) body repair.
Have seen some JB Weld work in a few places, But never been aware of an epoxy used in an exhaust port and it hold up.
not to sound like a nay-sayer, i'd like to see it work. Education is the main reason I'm here.