MCCULLOCH The official McCulloch thread

[Dream]

I think what happens on the horizontal 10 series engines is because they have a bottom exit exhaust .Some mufflers have a curvature in the bottom and some it just hits a sharp bend with no curvature .
In the later depending on the design they could make another bend on the outlet .Combine that pizz poor design with the fact they use an impulse operated oil pump that will in some degree suck chain oil into the crankcase .This pyrolites, effectively turning into petro coke which chews up the exhaust side of the piston in time .The air filters aren't the best design which works on the intake side .
The best of those mufflers are the ones with a curvature with large baffles and no second curve .The worst are those square things with screens .If you want them to run omit the baffles and wear ear plugs,you're going to need them .Then just about like every McCulloch you have to tune them just a wee bit rich . BTW you have to knock the sawdust off those filters more often than a more modern saw .You get passed all that a 700 is a pretty dependable saw with plenty of power .

Yes Sir.
I love the 10 series. They seem to be the best built and most user friendly of all that ive run. Also best torque or what I call "grunt" in the cut. Seems like They get through faster than some of the modern saws because they dont stall if you need to Dog in a bit. Have a friend with a 372 XP. Let him stump a pine with the PM700. He was impressed by how it went through, even with dogging it hard. Used all of the 28" bar and full comp chain to get through.
I understand what you say about the muffler. That one has the power reed muffler. The reed broke long ago I assume. It does seem to have a curve at the exhaust port, bit id like to modify the second section and just dump it toward the grass. Need earplugs anyway.
Wish there was a simple way to put on a better filter.

 

[Steve]

Wish there was a simple way to put on a better filter.

There is! Velocity stack.

 

[Al Smith]

I never really figured out what a reed muffler was supposed to do but assumed it was like a power valve on a tuned pipe dirt bike .Everyone I had had a rusted out spring so it didn't work any way or was rusted shut .I think I still have them in a box some place because I seldom throw anything away .I just forget where they are at .Fact I still have those f---ked up big fat below the cylinder mufflers from the 850's in a box someplace too . I think they tried to make them quiet but forgot all about how they ran .That's must have been before they made ear plugs because there is no hot preforming quiet saw I'm aware of .--as I type with a ringa ding in my right ear .

 

[heimannm]

Everything you ever wanted to know about the reed mufflers.

Mark

 

[Al Smith]

Although that file didn't delve into true physics of it's design it would appear it operates similar to a "slide pipe " .The difference would be it really doesn't back charge the cylinder like a tuned pipe .In essence the back pressure would appear to attenuate the pressure rises IE opposing forces ,self cancelling to a point .
The basic idea of a baffled type muffler is it bounces the sound waves hither and yon with some of them creating opposing forces which cancels out some of the sound levels ,Now that makes sense if you really think about it from a noise standpoint .The idea of the spring loaded "reed" probably works to a point except if it rusts up or the spring becomes inoperable .

 

[Dream]

All of mine with power reed mufflers are 700s. The reed cracked and sheared off or was removed long before they came to me. Dont have any of the valve type.
I love the sound of these things, even though its bad for the ears. I'll put on muffs once I'm cutting, but I like to listen to them when I cold start and warm them up. Also lets me know how they are doing, and if theres something I need to work on. 7-10A is gonna need a clutch soon.

 

[tomscott]

Gentlemen - I am trying to resurrect a PM 610 for a friend. Fuel cap was blowing fuel, and I couldn't be sure it was just the gasket or also the vent, so I pressed what I thought would be the "Easy Button" and ordered a replacement cap from eBay, advertised as new and never installed.

Upon receipt, the inside of the bag had splotches of black goo. What should have been the tank vent hole appeared to be closed off and filled neatly with something shiny. I touched it and it wasn't just shiny, but wet black goo. Unfortunately no "before" pics, as I touched it before I could comprehend and it stuck to my fingers and wiped it off with a paper towel. The first two pics show some remains of the black goo as a shiny area pointed at by my pick. Some of the goo got on the pick end.


This pic shows condition of inside of bag. Some goo appears to have dripped out during its time in the bag and an idea of how much I had to wipe off my fingers.

Top of cap to help clarify what generation cap I received.


I can see the coil spring inside the hole. My gut is telling me that for some reason someone filled it with black RTV as now that an hour has passed what I have wiped on the paper towel has solidified. Questions:

1. Is this hole supposed to be open? I would think so, but I want to be sure there wasn't some type of duckbill that turned to goo.
2. Should I be able to see anything other than the coil spring looking into the hole?

I'm turning to you guys as I don't want to go back to the seller uninformed. Either way, it was advertised as "new and undamaged", but I'm not confident in installing this. If I clean it up and it leaks from the vent I've lost my ability for an eBay claim. Any help is much appreciated!

Thanks, Tom

 

[Steve]

Gentlemen - I am trying to resurrect a PM 610 for a friend. Fuel cap was blowing fuel, and I couldn't be sure it was just the gasket or also the vent, so I pressed what I thought would be the "Easy Button" and ordered a replacement cap from eBay, advertised as new and never installed.

Upon receipt, the inside of the bag had splotches of black goo. What should have been the tank vent hole appeared to be closed off and filled neatly with something shiny. I touched it and it wasn't just shiny, but wet black goo. Unfortunately no "before" pics, as I touched it before I could comprehend and it stuck to my fingers and wiped it off with a paper towel. The first two pics show some remains of the black goo as a shiny area pointed at by my pick. Some of the goo got on the pick end.

View attachment 243751 View attachment 243752
This pic shows condition of inside of bag. Some goo appears to have dripped out during its time in the bag and an idea of how much I had to wipe off my fingers.
View attachment 243753
Top of cap to help clarify what generation cap I received.
View attachment 243754

I can see the coil spring inside the hole. My gut is telling me that for some reason someone filled it with black RTV as now that an hour has passed what I have wiped on the paper towel has solidified. Questions:

1. Is this hole supposed to be open? I would think so, but I want to be sure there wasn't some type of duckbill that turned to goo.
2. Should I be able to see anything other than the coil spring looking into the hole?

I'm turning to you guys as I don't want to go back to the seller uninformed. Either way, it was advertised as "new and undamaged", but I'm not confident in installing this. If I clean it up and it leaks from the vent I've lost my ability for an eBay claim. Any help is much appreciated!

Thanks, Tom

That goo is the 30 year old duckbill valve. They do that. You can try to repair the cap with a duckbill valve from a homelite or stihl.

 

[Gizzard]

That coil spring should assist with holding the rubber duck bill in place. I replaced one with the green stihl rubber duckbill that fits in side of MS170, 017 fuel tank and quite a few other Stihl models. Local Stihl dealer charges $0.99/ea.

 

[heimannm]

I prefer to work the new duckbill valve in through the hole without taking the cap apart. Either the green Poulan one or the red Homelite will work, sorry I don't have the part number handy right now. Be sure to clean out all of the black goo, carburetor cleaner works for me, it takes several rinses and wipes before it come out clean.

Mark

 

[tomscott]

Thanks everyone for the quick replies. Crap. I know, easy fix, but I paid top dollar to get a perfect NOS cap. Yeah, I know old rubber and plastic disintegrates, but it was advertised as "undamaged". The picture of the underside on eBay was fuzzy.

Mark, you may not remember, but you helped me about 7 years ago with a domed air filter for my 10-10. You also advised me on replacing the duck bill valve in the 10-10 cap. Minimal damage disassembling the 10-10 cap, duck bill worked perfect. Very much appreciated the help then, and now.

I have one duck bill left in stock, I bought an extra at that time.
Is this duck bill a good choice for this cap as well? Or is the longer Poulan style preferred? Does the Stihl look similar?
I assume the "bill" (pointy end) goes towards the inside of the tank, otherwise I don't think the air would get in as you use fuel.
Thanks to all!

 

[heimannm]

That one should work just fine. You need to make sure the flange on the bottom of the duck bill valve is properly seated against the spring so it pushes the valve against the cap to make a tight seal. If not you will continue to have fuel leaking out of the cap when the saw is in operation. So, yes, the duck bill portion will stick out of the cap.

7 years ago...I hardly remember what I did last week...good to know you are still with us.

Mark

 

[heimannm]

From this...



...to this...



...to this...



...to this.





Mark

 

[Gizzard]

Is this duck bill a good choice for this cap as well? Or is the longer Poulan style preferred? Does the Stihl look similar?
I assume the "bill" (pointy end) goes towards the inside of the tank, otherwise I don't think the air would get in as you use fuel.
Thanks to all!
View attachment 243779

The green Stihl duckbill as from ms170 fuel tank tank matches the Poulan. I use the Stihl on Poulan, Husqvarna, whatever, in the shop. A few repairs will use the shorter red homelite duckbill. Depends on hole diameter in spring clip that holds duckbill base firm to cap.

 

[Dream]

From this...

View attachment 243794

...to this...

View attachment 243795

...to this...

View attachment 243796

...to this.

View attachment 243797

View attachment 243798

Mark

Nice work Mark!
Id love to try one of those one day. I hear they have some snort to them.

 

[Al Smith]

I copied the part numbers which may be a solution for a Lauson Carb on a Power Products AH 58 engine .This carb uses check valves unlike a Tillotson with flapper types .I managed to blow one into orbit trying to repair the carb some time ago . The story about that old gear drive Sears chainsaw is lengthy,I'll spare the details .Although I might add I did manage to blow the flywheel loose which orbited my garage about twice with me ducking as it nearly hit my wife's Cadillac .--Do not ever think you can spin up an engine with a drill motor ,even with a ratchet because it will spin off .

 

[tomscott]

The green Stihl duckbill as from ms170 fuel tank tank matches the Poulan. I use the Stihl on Poulan, Husqvarna, whatever, in the shop. A few repairs will use the shorter red homelite duckbill. Depends on hole diameter in spring clip that holds duckbill base firm to cap.

Ok, good to know, just two types to choose from keeps it simple! I ordered some of the green ones anyway, so I'm covered now. Thanks!

 

[Dream]

The green Stihl duckbill as from ms170 fuel tank tank matches the Poulan. I use the Stihl on Poulan, Husqvarna, whatever, in the shop. A few repairs will use the shorter red homelite duckbill. Depends on hole diameter in spring clip that holds duckbill base firm to cap.

Sent you a PM.

 

[heimannm]

Yesterday...



Today...two trailer loads and two truck loads (Ranger) later.



Some of the WMD's I used.



I used the PM55 extensively to noodle up the large rounds (48"+) into manageable size pieces. What a perfect saw for a job like that. I cut them about 16" long for the lady getting the firewood to make sure they would fit her wood stove and the 16" bar would not quite reach all the way through with the spike in place so I could leave the large rounds stacked right in place and whittle them down one by one.

It was almost 90 degrees yesterday and just over 90 degrees today; hot, tiring work but it done now.

American elm by the way, some of the pieces would not split so I chunked them up with the PM55 and left what you see in today's photo for the land owner to dispose of.

Mark

 

[Al Smith]

Elm is nearly impossible to split short of a hydraulic splitter . It's unusual to even find one that large as most of them died off in the 60's .The few in my woods rarely make it a foot in diameter ,usually half that .