MCCULLOCH The official McCulloch thread

[cinci5]

Hi Jeff,

I would assume that small raised line cast into the cylinder is to create a pressure or crush point on a soft gasket. My Printing company screen prints silicone beading on gaskets for local gasket companies and this is used to help seal better than a gasket alone by creating this high pressure "ridge".

I don't see a step so much as a raised "row" of material that would essentially do the same thing.

Brian Genrich
Old Saw Shop

I understand that but the muffler bottoms out on the raised pedestals not the ridge. I would think that they would have gone flat with a ridge (crush) point on a independent flat surface and not raise the muffler off it, that is my question.
Not a biggie it was the 70's which I remember vaguely

ps Any suggestions for a fuel line ? Was gonna try tygon and grommet method but plug and play would be nice

 

[jacob j.]

Here's something you don't see everyday: https://www.ebay.com/itm/335220700589

A kit to convert your Mac 15 from Tillotson HC to Tillotson HS. It's similar to the HL/HS switch on the 797/Super 797.

At first, I thought the carb was missing the fuel pump cover, diaphragm, and gasket, however those parts aren't included
because I think it would still be set-up for gravity feed? The IPL shows it set-up like that.

 

[legdelimber]

I'm wondering if the intent was to allow a moderate amount of gasket compression for sealing, yet not letting the pressure squash the gasket to the point of breaking and crumbling out?

Or was there a heat shield (as heimannm mentioned) that might have been a design revision that was easier or more cost effective to implement/install using the step to hold it vs using a larger piece of sheet stock to incorporate the bolt holes?

Putting the SP125 back together and was wondering why a stepped area around the exhaust gasket section.
I made a copper gasket on the CNC Mill to fill in but why is there a step there to begin with.

 

[Steve]

I'm wondering if the intent was to allow a moderate amount of gasket compression for sealing, yet not letting the pressure squash the gasket to the point of breaking and crumbling out?

Or was there a heat shield (as heimannm mentioned) that might have been a design revision that was easier or more cost effective to implement/install using the step to hold it vs using a larger piece of sheet stock to incorporate the bolt holes?

I bet it was more to keep the muffler bolts tight since if there was no gasket to burn out or shrink the bolt torque would stay more consistent.


I have noticed this practice on the 10 series later cylinders too. The 1,2,3,4,5,6-10 and early 10-10 all used a traditional gasket on a flat cylinder flange. 6-10SA , later 10-10 and every other 57, 62, 70, and 82cc cylinder that I have had my hands on used a rectangular recessed gasket on the exhaust gasket.

Like all things McCulloch nothing is set in stone as rule. I'm sure Mark has seen many exceptions to my above statement but it does seem most the later 10 series saws use that style of recessed gasket.

 

[heimannm]

Some of the MAC15 models came with the Tillotson HC carburetor, basically an HL without a fuel pump.



Others came with an SDC 7 which is an SDC without a fuel pump.



If you look closely at the photos in JJ's link you can see the fuel inlet barb sticking out of what would normally be the fuel pump side of the carburetor.

Steve is right on target, the early 10 Series saws had a more conventional gasket, and all the later ones had a recess and a captured gasket, 84007 on all of the smaller saws and 84577 on the 82 cc models.

On the big saws, starting with the PM105 they all had the recessed pockets for the gasket and the larger 89224 gasket like you see in the IPL illustration above. If I read the IPL's correctly the later 795L models and replacement blocks for the S797 would have incorporated arecessed gasket pocket and used the 87339 gasket. There may be some other late edition large frame saws that also used 87339 but I can't come up with one right now.

Mark

 

[Turd Furgeson]

Here's something you don't see everyday: https://www.ebay.com/itm/335220700589

A kit to convert your Mac 15 from Tillotson HC to Tillotson HS. It's similar to the HL/HS switch on the 797/Super 797.

At first, I thought the carb was missing the fuel pump cover, diaphragm, and gasket, however those parts aren't included
because I think it would still be set-up for gravity feed? The IPL shows it set-up like that.

My Mac 15 has the tillotson HC carb. I was kinda pissed when it first showed up from ebay as I thought somebody buggered it together. After a little inspection I realized it came that way, a bit of digging online confirmed that. Seeing the carb without the cover really threw me.

 

[Squareground3691]

Old Mcculloch Chart , 18x24”

 

[Rallyeguy]

I understand that but the muffler bottoms out on the raised pedestals not the ridge. I would think that they would have gone flat with a ridge (crush) point on a independent flat surface and not raise the muffler off it, that is my question.
Not a biggie it was the 70's which I remember vaguely

ps Any suggestions for a fuel line ? Was gonna try tygon and grommet method but plug and play would be nice

I still think that if there is a ridge that it creates a crush point even if ithe muffler flange lands on a surrounding ridge instead of seating only on and compacting only the gasket. I would have guessed like you that it would have seated only on the gasket. I know Copper being a softer metal works very well with header collector gaskets, and never burn out so I like what you're doing with it.

One the fuel line....I'd probably do a tygon alternate, but I am not speaking from actual experience. I haven't played with a 125 yet...Unfortunately, I can't be more helpful on that for you..

 

[heimannm]

I spent some time today trying to get various DSP valves sorted out. I tried to research some "where used" from my collection of electronic and hard copy IPL's. I am missing examples of several, if anyone has an example of 63615, 64714, 64755, 83137, or 83166 I'd like to see a good photos and some basic dimensions.

Part #	Description	Alternate Part #	Where Used	Price	New
63615	Valve - DSP	86295​	795/895 early		0
64714	Valve - DSP		5-10, 6-10, 5-10G, LG6		0
64755	Valve - DSP		2-10, 3-10, 3-10E		0
65910	Valve - DSP .310x1.130 umbrella type	83137​	5-10E		+
69877	Valve - DSP .243x1.225 long 1 hole + slotted		795L, 797, CP125		+
83070	Valve - DSP .248x1.565 long 1 hole		CP70		+
83137	Valve - DSP	65910	5-10, 6-10, LG6		0
83166	Valve - DSP	2-10 10677-, 3-10E, Super 10-10E,		0
84217	Valve - DSP .248x1.130 long umbrella type		2-10 10677+, 3-10		+
84221	Valve - DSP .249x1.165 long umbrella type		6-10 12502+, 7-10		+
84315	Valve - DSP .248x1.630 long 1 hole		CP70L		+
86295	Valve - DSP .248x1.070 long 1 hole	86280​	795 895 w/replaceable seat		+

Mark

 

[heimannm]

86295 (above) is used with a threaded insert 86280 on later editions of the 795 and 895 models.

Mark

 

[Duke Thieroff]

Hey!

Does anyone have a Mac Model 99 IPL?

 

[nbbt]

Hey!

Does anyone have a Mac Model 99 IPL?

Check your inbox for one from '58

 

[Bigmac]

So @cinci5 question about the exhaust gasket got me looking, noticed something new about the SP 125 and 125C. I knew the exhaust port was different, but didn’t realize the muffler and gasket were different. I finally got and early sp125 block, so I can finally see the differences

 

[jacob j.]

So @cinci5 question about the exhaust gasket got me looking, noticed something new about the SP 125 and 125C. I knew the exhaust port was different, but didn’t realize the muffler and gasket were different. I finally got and early sp125 block, so I can finally see the differencesView attachment 406113View attachment 406114View attachment 406115View attachment 406116View attachment 406117

Also, the fin arrangement on top is different. They had more fins on the early cylinders and less on the later. I wonder if it was because fins were busting off of the early cylinders?

 

[Bigmac]

Also, the fin arrangement on top is different. They had more fins on the early cylinders and less on the later. I wonder if it was because fins were busting off of the early cylinders?

Could be, I wondered if it was to be more open so chips and debris wouldn’t clog them up. You know how packed they get!!

 

[Bigmac]

My explanation of the exhaust gasket change was like Steve and mark said, one, as a heat shield, second a much better way to torque the exhaust bolts directly to the cylinder, and my third opinion was easy of manufacturing and installation, mufflers on these were much more durable and installing the exhaust gasket is much easier to install than previous. The muffler was much cheaper to make.

 

[legdelimber]

Just saw your posts. I was about to ask how did the air shroud seem to route the air on the two different heads or cylinders?
And how did the debris or dirt patterns look on the fins and also on the shroud, both inside and outside (Leakage or blocking of flow).
,What did they tell about the air flow? Bolt bosses with more dust behind one style or the other, Just anything that speaks to speed or volume of air flow?

Was the flywheel any different shape or diameter, fins thicker or the pawls different?
Wiring laid out different?
Any flash blocking around fins or openings on the block or heads?
Just anything that might alter or improve or block the air flow.

Also, the fin arrangement on top is different. They had more fins on the early cylinders and less on the later. I wonder if it was because fins were busting off of the early cylinders?

Could be, I wondered if it was to be more open so chips and debris wouldn’t clog them up. You know how packed they get!!

 

[Squareground3691]

My explanation of the exhaust gasket change was like Steve and mark said, one, as a heat shield, second a much better way to torque the exhaust bolts directly to the cylinder, and my third opinion was easy of manufacturing and installation, mufflers on these were much more durable and installing the exhaust gasket is much easier to install than previous. The muffler was much cheaper to make. View attachment 406126View attachment 406127

Alright stop showing off all ur cool stuff, Lol great job , Nathan

 

[Bigmac]

Just saw your posts. I was about to ask how did the air shroud seem to route the air on the two different heads or cylinders?
And how did the debris or dirt patterns look on the fins and also on the shroud, both inside and outside (Leakage or blocking of flow).
,What did they tell about the air flow? Bolt bosses with more dust behind one style or the other, Just anything that speaks to speed or volume of air flow?

Was the flywheel any different shape or diameter, fins thicker or the pawls different?
Wiring laid out different?
Any flash blocking around fins or openings on the block or heads?
Just anything that might alter or improve or block the air flow.

I haven’t tore down enough of them with that mindset's to tell, they made a ton of changes from the cp125 to the last sp125c wiring, coil,muffler shroud, fan shroud and decomp. Plus others that I’m probably missing in the cooling path. The side fins always get packed, some saws are just grungier than others too

 

[Spike60]

About time for you McCulloch dealers to do your spring orders.