McCulloch Chain Saws

[Maintenance supervisor]

This is a picture of the actual check valve kit , the brass insert is upside down to show the diameter of the hole that said diaphragm is supposed to be squeezed through? If someone can post on how to do that with confidence that the new diaphragm( new diaphragm shown)is not injured I'd be impressed.
The removal is pretty easy and doesn't really require any special tools.
I modified a wood screw so that the tip doesn't plow into the aluminum body when screwed into the brass.
Drive the new brass insert down ,and make sure you drove it past the ports.

This is what it looked like before ,looks good but cheese cloth thin and wore out.
The brass insert I removed could be reused but its rare that happens.

 

[PogoInTheWoods]

If someone can post on how to do that with confidence that the new diaphragm( new diaphragm shown)is not injured I'd be impressed.

I would say that'd be impossible. Shouldn't you remove the insert just to make sure there's no crap underneath and to ensure a clean seat for the new diaphragm anyway..., and to install the new insert?

Puzzled.

 

[Maintenance supervisor]

I would say that'd be impossible. Shouldn't you remove the insert just to make sure there's no crap underneath and to ensure a clean seat for the new diaphragm anyway..., and to install the new insert?

Puzzled.

Yes, but its been posted that it would be possible to get the old diaphragm out and get the new one in without removing the brass insert.

 

[PogoInTheWoods]

Yes, but its been posted that it would be possible to get the old diaphragm out and get the new one in without removing the brass insert.

In that case, I'm anxiously awaiting the answer to your original question! LOL

 

[RolandM]

Yes, but its been posted that it would be possible to get the old diaphragm out and get the new one in without removing the brass insert.

Come on guys - surely fitting an object through a tight orifice is a worthy challenge! Just knocked up a tool today to cut the diaphragm material, but carelessly left it at work. So it will be tomorrow at the earliest I get the chance to perform!

Roland.

 

[Maintenance supervisor]

Come on guys - surely fitting an object through a tight orifice is a worthy challenge! Just knocked up a tool today to cut the diaphragm material, but carelessly left it at work. So it will be tomorrow at the earliest I get the chance to perform!

Roland.

I'm pretty sure that you'd have to be an origami master to do it!

 

[Maintenance supervisor]

I got a chance to tear down my 10-10 that got crushed by a sweetgum . I had gotten this saw from a scrap yard and gave it the usual attention, but the only spare carb I had already rebuilt was a fixed high jet sdc . After running it for awhile I was convinced that the carb gave it a little extra grunt . Upon disassembly I discovered this though...
I'm not totally sure that it makes a huge difference but this saw does run great.

 

[T_zero]

Thanks Mark!

If that method works for you I'll see if I have something i could put in my drill. Then I'll just rinse it out with some Brakleen.
I'm close to reassembling the SP40, it looks like I need a second set of feeler gauges to set the clearances on the crank bearings. Did you see my picture of the broken main cap bolt? That's why the bearings felt loose! The flywheel side bearing actually drifted outward a little and let the crank counter weight rub slightly on the case. I just had to deburr a sharp raised edge where the bearing seats on the case, all looks good to be assembled.

what do you mean with feeler gauges to set the clearances on the crank bearings ??

 

[MacAttack]

what do you mean with feeler gauges to set the clearances on the crank bearings ??

On an SP40, the engine is a clamshell, the bearings are not seated in pockets in the case. They just float on the crankshaft and are held in position by the "main cap" bottom of the case. You manually set the positions and axial play of the bearings with feeler gauges and then clamp the main cap onto them.

 

[T_zero]

do I need to do that on a pro mac 850 ?

 

[MacAttack]

do I need to do that on a pro mac 850 ?

A PM 850 is a much bigger saw, so I would assume it's different. But I'm sure someone else here could tell you for sure.

 

[heimannm]

The crankshaft position is fixed by the locating ring on the flywheel side bearing and the bearing insert is fixed in position by a dowel pin on the PTO side on the PM850.

Mark

 

[T_zero]

The crankshaft position is fixed by the locating ring on the flywheel side bearing and the bearing insert is fixed in position by a dowel pin on the PTO side on the PM850.

Mark

so i don't need to use feeler gauges, right?

 

[Maintenance supervisor]

Any body live near up state Pennsylvania? Lower new York. https://williamsport.craigslist.org/grd/d/mansfield-lots-of-old-small-engine/7110928046.html

 

[Maintenance supervisor]

so i don't need to use feeler gauges, right?

No , and you can watch someone put it together on YouTube. Bellhopper.

 

[RolandM]

I'm pretty sure that you'd have to be an origami master to do it!

Pleased to report a successful conquest of this hole problem! With a good tool I was able to cut some tight sharp wads out of a spare diaphram like this.

Again with another good blunt tool the job was done and the disc implanted.

The valve checks well so all remains is to fit the core plugs. I use loctite bearing fit which is I find very fuel proof and then I can fit the rest of the kit. Still got a fair bit of cutting lined up for the pro mac 555 so should get a ~gallon thru it over the weekend to check all is well. Then I get back on to the promac 700, which I have already ported the intake. Will pick up where I left off on that so to finish that story!

Roland

 

[PogoInTheWoods]

Nicely done. Do you also fashion your own welch plugs by chance? (Or is that what you mean by "core plugs"?) I need one for a Tillotson I'm working on that already has new diaphragms so don't want to buy a whole RK just for the welch plug. I rednecked one from a flattened Zama plug that is pretty embarrassing, though it is air tight. It's sitting on the ridge provided for the normal plug and looks worse than its, but I'm just a little concerned about the possible reduction of chamber flow volume by it lacking the normally domed shape. I'd be interested in anyone else's approach to making your own plugs. A punch and a beer can?

​

 

[RolandM]

Nicely done. Do you also fashion your own welch plugs by chance? (Or is that what you mean by "core plugs"?) I need one for a Tillotson I'm working on that already has new diaphragms so don't want to buy a whole RK just for the welch plug. I rednecked one from a flattened Zama plug that is pretty embarrassing, though it is air tight. It's sitting on the ridge provided for the normal plug and looks worse than its, but I'm just a little concerned about the possible reduction of chamber flow volume by it lacking the normally domed shape. I'd be interested in anyone else's approach to making your own plugs. A punch and a beer can?

View attachment 829663​

Core plug - local lingo for welch plug. I just use the ones in the kit, minimum loctite applied with a pin to the recess, and gently expanded with a suitable flat punch. I did turn one up on the lathe once for McCulloch flat back. was about 1" dia and it worked fine. I suppose for the small ones it would be best to turn something biscuit shaped about 0.001" up, out of soft aluminium.

Roland.

 

[Maintenance supervisor]

Ni

Pleased to report a successful conquest of this hole problem! With a good tool I was able to cut some tight sharp wads out of a spare diaphram like this.View attachment 829638

Again with another good blunt tool the job was done and the disc implanted.
View attachment 829650
The valve checks well so all remains is to fit the core plugs. I use loctite bearing fit which is I find very fuel proof and then I can fit the rest of the kit. Still got a fair bit of cutting lined up for the pro mac 555 so should get a ~gallon thru it over the weekend to check all is well. Then I get back on to the promac 700, which I have already ported the intake. Will pick up where I left off on that so to finish that story!

Roland

Nicely done sir, I stand corrected.
You should notice a pretty dramatic difference in performance now.
Whats the blunt tool you used?

 

[Brian Thacker]

Any body live near up state Pennsylvania? Lower new York. https://williamsport.craigslist.org/grd/d/mansfield-lots-of-old-small-engine/7110928046.html

So you want that Craftsman lawnmower?

Brian