MCCULLOCH The official McCulloch thread

[Lee H]

I wonder if any current saws use a Q-port? Maybe the idea died. Seems to take some of the of the zip out of them.

Mark, on that water in the CP 70. Makes perfect sense now, the guy I got it from mumbled something about it being a boat anchor...

I finally have my SP125 restored and running good. I couldn't find a coil for it, so I made one out of a Husky 55 coil. It was a fast and cheap mod. Husky 55 coils are solid state and only cost 10 bucks. I just swapped the laminates and bolted it on. Not sure this pic will load.View attachment 14730

That's an awsome tip. I've been wondering what coil would work
in the two leg laminates.


Lee

 

[Al Smith]

The SP 125 used a 10 series coil ,the CP 125 used the big coil like on a 250 etc .
Nobody can agree in whole what the Q port exhaust was for .Some say for quietness and some say the Q relieved some compression on start up .If I recall the Mac 1000-Partner p100 I tinkered with a few months ago had a Q.IMO it was a rather stupid idea. .

 

[Al Smith]

Now on putting some soup to a ten series style saw like the 82 cc's I really don't have any idea except bump the timing a tad and some exhaust work .There's really no practical way to raise the compression and what if anything could be done with the transfers would be a moot point .

 

[Ikeholt]

On that coil swap, you do need to trim down the Mac laminate some. I used a bench grinder. I would think this would work on 10 series Macs as well. At 10 bucks you can buy a new one-piece coil cheaper than replacing the points.

 

[WOODS]

Mark H. has a Mac publication on the changes from the old 850 to the 800. I assume the "Q" in Q-port has to do with noise but I believe the purpose was related to starting ease by bleeding off compression. The original 800 did not have a DSP. Many later models in the series had a small port drilled in the center of the bolt boss for the muffler brace (same general location as the DSP clean-out on older style) and a special 3/8" coarse thread DSP valve that replaced the hanger bolt.

Below are pictures of two NOS cylinders - old style on left and new on right. The old style was the one I sold; I still have the new style. Ron

___________________________________ Q-port - exhaust port appears to be smaller ________________________________ Note the raised intake - upper right side _____

 

[ft. churchill]

I have some questions that some of you may be able to help with. On the 555 I'm working with, how do you identify the carb? It's certainly a flat back, and it has the primer system instead of a choke. It has an "S" stamped on it in one location, and the numbers 68721 stamped into the carb mounting flange.

The sugarcreek saws carb kit does not list the 555 as a saw that their kit will fit. Any ideas? Will the scs kit have most of the components I'll need to get her goiing?

 

[ft. churchill]

Here is another one for you folks. When looking down into the intake flange where the carb mounts onto, I see the two phenolic reeds, but what is the other port on the left (starter/flywheel) side of the saw? The boost port?

 

[heimannm]

You need to put up some photos on that saw Churchill, 555 is a 10 Series piston ported saw. Perhaps you mean to say 550? The 550 would have used a McCulloch/Walbro "flat back" carburetor and the kits Joe sells would be correct but only contain the gaskets and diaphragms. For other parts (metering needle, check valve or capillary seal, etc.) you have to keep digging. Primers are not repairable and replacements are hard to find. You can always prime them right down the throat of the carburetor to get the going then fill up with the saw running, convenient with the fuel cap on the top like that.

The extra passage you see is the "3rd port induction" or "3rd port transfer". McCulloch advertised this feature but I understand some of the kart racers would actually plug the chamber up to reduce the volume in the intake region. I cannot explain...



Third port on the 795 block on top, no third port on the SP105/125 block on the bottom.



Mark

 

[heimannm]

According to Service Bulletin 1707 the "Q" port lowers compression at starting speed eliminating the need for the DSP, smooths out the idle, and reduces exhaust noise.

Furthermore, the large volume low tone muffler reduces noise without any power loss.

The spark arrestor screen meets US Forest Service regulations and reduces skin temperature.

The flywheel has longer fins for better cooling.

The third port boot improves idling and cutting in all positions.

I have PM800 with and without the DSP so I assume with and without the "Q" port.





The Super PM850 (at least the one that I have) also has the "Q" port and no DSP.



When I was putting of the 800's back together I noticed the rather rough looking flashing around the intake and thought I'd better smooth it out so as not to risk having a chip break off and ruin the piston and cylinder. By the time I was done I had inadvertently completed my first porting job reshaping and resizing the intake by a fair bit. That saw has the "Q" port and is a bit more feisty to start, but it does run very well.

I don't have a current family photo with all of the saws included, but the middle row contains PM800 w/DSP, PM800 w/o DSP, PM805, PM8200, and DE80. the Super PM800 is now residing in line as well, still need to find the CP DX80.



Mark

 

[heimannm]

12, 18, and 24 fin flywheels, the 18 has the taller fins described in the PM800 Service Bulletin.



Mark

 

[ft. churchill]

You need to put up some photos on that saw Churchill, 555 is a 10 Series piston ported saw. Perhaps you mean to say 550? The 550 would have used a McCulloch/Walbro "flat back" carburetor and the kits Joe sells would be correct but only contain the gaskets and diaphragms. For other parts (metering needle, check valve or capillary seal, etc.) you have to keep digging. Primers are not repairable and replacements are hard to find. You can always prime them right down the throat of the carburetor to get the going then fill up with the saw running, convenient with the fuel cap on the top like that.

The extra passage you see is the "3rd port induction" or "3rd port transfer". McCulloch advertised this feature but I understand some of the kart racers would actually plug the chamber up to reduce the volume in the intake region. I cannot explain...

View attachment 14803

Third port on the 795 block on top, no third port on the SP105/125 block on the bottom.

View attachment 14804

Mark

Thanks Mark.
Yes I made a mistake I'm working on a 550. The nice clear photo you've got looks just like the 550 I'm working on. My saw has the opening similar to the 795.

 

[joeymt33]

I did cut a piston on one for Joey. He said it helped.

I didn't really see any sure gains aside from that though.

Hey guys, I haven't been around in awhile but I'm still cutting and only own Macs.

And yes, that saw with the shaved piston will out cut my others on ~20" logs and under. It won't hang with my 200psi PM850 for milling though, I tried that.


Sent from my iPhone 10s

 

[joeymt33]

Why is it that all Craigs list ads for chainsaws that don't run say, "it used to run"?

I would say that's pretty obvious.

Rant over


Sent from my iPhone 10s

 

[heimannm]

Hey Joey, good to know you are still with us.

Here's a possible exception to your rule, if it was the blue and white saws O&R made for Ford tractor my understanding is many of them never ran.



Mark

 

[joeymt33]

Hey Joey, good to know you are still with us.

Here's a possible exception to your rule, if it was the blue and white saws O&R made for Ford tractor my understanding is many of them never ran.

View attachment 14823

Mark

I need to get my hands on one of those. I've had a picture for years and have been looking but no luck.


Sent from my iPhone 10s

 

[WOODS]

Mark, I believe if you pull the mufflers on your DSP equipped saws you will find that they have the same exhaust port as the non-DSP model. The only difference that I am aware of is the drilled port in the muffler bracket bolt boss. What I don't know is what is this third port boot? Though the intake port is different I have not noted any difference in the pieces between the port and the carb. Do you know to what they are referring?

On a personal note the mail brought a smile after ending my day dealing with asinine federal government positions. Thanks.

Ron

 

[WOODS]

Joey, 200 psi. Wow, no wonder it is stronger. I believe 165 is the best reading I have on a Q-port. Most are 160; the 8200 was about 130; about the same as my PM700. My best old style was 175, but they were all well used.

Ron

 

[Al Smith]

How in the world did you crank 200 PSI out of that saw?

Now that so called third port thing was something they did on the Mc70 Kart engine .It had a set of ports running up the back from the crankcase .Call them boost ports,exteriors or what ever they just allowed a more evacuation of the exhaust gasses .

Some of the saw engines which kart engines were patterned after had provisions to cut the two extra ports in .Which ones I'm not entirely certain of .You could probably cut in more holes than two .

Much controversy about the first Mc kart engine .Two are mentioned ,the Super 44A and the 1-70.I have the former but not the later although I do have a 44 super .Of which if and when I get the inspiration is destined for a vintage racer .Under the wraps of a 250 because I hate right hand starts .

If you take a gander on Mc Bobs site it lists the ones that have provisions you could add those ports as well as the sizes and shapes of them .

 

[joeymt33]

How in the world did you crank 200 PSI out of that saw?

Now that so called third port thing was something they did on the Mc70 Kart engine .It had a set of ports running up the back from the crankcase .Call them boost ports,exteriors or what ever they just allowed a more evacuation of the exhaust gasses .

Some of the saw engines which kart engines were patterned after had provisions to cut the two extra ports in .Which ones I'm not entirely certain of .You could probably cut in more holes than two .

Much controversy about the first Mc kart engine .Two are mentioned ,the Super 44A and the 1-70.I have the former but not the later although I do have a 44 super .Of which if and when I get the inspiration is destined for a vintage racer .Under the wraps of a 250 because I hate right hand starts .

If you take a gander on Mc Bobs site it lists the ones that have provisions you could add those ports as well as the sizes and shapes of them .

Al, I've actually had two of them produce 200psi. I'm not sure why, I didn't do any modifications at all. The least compression of the ~12 or so I've got is probably in the 165psi range. I thought that was the norm.

Oh, and just incase you wondered how did I crank the saw.....it wasn't easy. Check the pics below.

Sent from my iPhone 10s

 

[joeymt33]

I found one of the pics I took when performing the test

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