McCulloch Chain Saws

[rwoods]

...

Lastly, the PM800/805/850 Super/DE80/M8200 saw without the "Q" port used a compression release valve with a short reach and coarse 3/8" (16 TPI) threads.

View attachment 664594

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Mark

Mark, I have never seen one of these models without a “Q” port. Seen the bottom of the boss for the muffler screw/DSP valve drilled and seen them blank, but all had the “Q” port. Has your experience differed?

As I am sure you know to equip a non DSP model (say a PM8200 or an early PM800) with a DSP just requires drilling a small vent/port hole in the bottom of the threaded boss and replacing the muffler bracket screw with a DSP valve.

I just put a tach on my PM800.

11,700rpm after it warms up....

It didn’t cut so well around 8,900 the last time a ran it prior to this week so I turned it up.

Now I know where it’s at.

Not sure how big the difference between chain or no chain rpms, but you might be leaving some on the table. Mine was at last tune 12,300 with no chain. The fresh RandyMac 850 was 12,500. Not sure now that it is in his hands how it is tuned and hopefully broken in. We do know that the 12,900 Brian was running with his 800 was too lean.

Ron

 

[hseII]

Mark, I have never seen one of these models without a “Q” port. Seen the bottom of the boss for the muffler screw/DSP valve drilled and seen them blank, but all had the “Q” port. Has your experience differed?

As I am sure you know to equip a non DSP model (say a PM8200 or an early PM800) with a DSP just requires drilling a small vent/port hole in the bottom of the threaded boss and replacing the muffler bracket screw with a DSP valve.



Not sure how big the difference between chain or no chain rpms, but you might be leaving some on the table. Mine was at last tune 12,300 with no chain. The fresh RandyMac 850 was 12,500. Not sure now that it is in his hands how it is tuned and hopefully broken in. We do know that the 12,900 Brian was running with his 800 was too lean.

Ron

It runs good @ 11,700.

Kinda safe. I might turn it to 12k, but I don’t see it making much difference.

It went from meh, 2100ish, to Well Hello, when I turned it up.

 

[Jethro 2t sniffer]

Id rather stay on the safe side too a sec or three wont make any difference for us firewood cutters.

 

[hseII]

If you have a File-O-Plate or other "progressive" depth gauge like the Husqvarna and match the rakers to the cutter, I will be fine.

Mark

I’ve been using this kit with great success.

Simple I know: I’ve got the Pferd thing but I like this.

 

[heimannm]

The problem with that depth gauge in a case like your damaged cutters is you cannot easily adjust the rakers lower on the damaged teeth. With the File-O-Plate the depth gauge adjusts to each individual cutter. Here is one example, the tooth is under the gauge and sets the height of the raker.


Mark

 

[heimannm]

Ron - PM800 with the compression release



My DE 80 came with a scored cylinder due to carbon accumulating in the DSP port and coming loose.



The plastic cap is missing but you can see the DSP valve.



Mark

 

[Jethro 2t sniffer]

The problem with that depth gauge in a case like your damaged cutters is you cannot easily adjust the rakers lower on the damaged teeth. With the File-O-Plate the depth gauge adjusts to each individual cutter. Here is one example, the tooth is under the gauge and sets the height of the raker.

View attachment 664610
Mark

Yea the stihl type isnt really very good and end up having to kinda geuss the shorter cutters. And the jerk behind the counter at the stihl shop will tell you they all need to be the same size and he sells you a new chain quicker

 

[edju1958]

Yesterday I went to visit a good friend of a lot of folks here - Bob Johnson of Maryland,N.Y.He & his "Honey"Joan showed us great hospitality.

 

[PogoInTheWoods]

The problem with that depth gauge in a case like your damaged cutters is you cannot easily adjust the rakers lower on the damaged teeth. With the File-O-Plate the depth gauge adjusts to each individual cutter. Here is one example, the tooth is under the gauge and sets the height of the raker.

View attachment 664610
Mark

Here's an example of the more readily available Husqvarna version which is depth gauge only. Same principle as the FOP. Only way to go for keeping rakers adjusted relative to each individual cutter, not to a specific height like a traditional fixed depth gauge tool works. These have settings for both soft and hard wood with the soft obviously being a little more aggressive. They just won't work on humped safety chain.

​

 

[hseII]

The problem with that depth gauge in a case like your damaged cutters is you cannot easily adjust the rakers lower on the damaged teeth. With the File-O-Plate the depth gauge adjusts to each individual cutter. Here is one example, the tooth is under the gauge and sets the height of the raker.

View attachment 664610
Mark

I’ve not seen that gauge: which one is that?

Disregard.

I See now.

 

[rwoods]

Ron - PM800 with the compression release

View attachment 664611

My DE 80 came with a scored cylinder due to carbon accumulating in the DSP port and coming loose.

View attachment 664612

The plastic cap is missing but you can see the DSP valve.

View attachment 664613

Mark

The presence or absence of that little hole and the valve is the only difference that I know. The exhaust ports on mine are all Q.

The 3/8 coarse thread can certainly be a pain to keep the valve tight. Seems to be an afterthought by MAC and easy to strip. I would have thought changing the threading of the cylinder would be easier than changing the threading of the valve.

Ron

 

[Jethro 2t sniffer]

So why did they use a valve and the Qport? I thought the Q was to do away with the valve.

 

[Jethro 2t sniffer]

Ron does your 850 exuast equipped 800 run as well as a non Qport engine?

 

[rwoods]

Even with the Q port there is a lot of strain on the starter assembly, though nothing like the non-Q models. I think the Q actually stood for quiet.

As to performance, I can’ t say. All the non-Q I have had were well worn. The one I had rebuilt for RandyMac was not broken in, but in the few cuts we made with it I couldn’t discern any real difference. All I can say is in my experience there is a noticeable range of performance difference within the same model saws. And I would suspect there is a slight compression advantage without the Q port. Other than marketing hype or a shift in operating range, I have no explanation of why MAC claimed the Q port big muffler saws have more horsepower - general consensus of those with the older saws is they have more power than the newer saws. I have no basis to doubt that, but am quite pleased with a well running Q port.

Ron

 

[Jethro 2t sniffer]

Yea ok so the power thing is more the muffler over the port. Yea it does take a decent yank on the cord its bitten me a couple times i had saw fingers and stoped drop starting it after that. Is there a set time when they started putting the decomps back in the 82cc models or was it an optional thing l assumed mine was an early version

 

[rwoods]

Don’t know the time line but I believe that later 800s and all models that followed other than the 8200 had DSP valves.

Don’t know the reason for the claimed hp increase, just know that the only differences that I know of were the muffler, the Q port and a slightly bigger intake port.

Ron

 

[rwoods]

Old on left and Q on right. The old seems to have an overall larger exhaust port, but I don't know that it does. The Q is the raise slot. Notice on the intake of the Q the raised slot on the right at the top of the port. Not sure what it does as the inlet insulator is the same for both models.

Ron

 

[Jethro 2t sniffer]

Ok thanks for the pics and info Ron much appreciated.

 

[PogoInTheWoods]

Dude.., don't you sleep? And isn't it already Tuesday down there er somethin'? LOL

 

[Jethro 2t sniffer]

Haha its monday nearly afternoon smoko