Old McCulloch chain saw - how adjust carb? - HobbyTalk
 
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post #1 of 7 (permalink) Old 04-09-2011, 04:26 PM Thread Starter
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Old McCulloch chain saw - how adjust carb?

I stopped using this chainsaw maybe 8 years ago and cleaned it up in anticipation of using it again. I got it started but it won't idle... gotta keep revving it up:
http://www.pbase.com/image/133779776/medium


I noticed these 3 adjustment holes with screws inside labeled T, H, L:
http://www.pbase.com/rlah/image/133779790


Should I adjust one of these to get the idle to work again? If so, can you be specific. Also, what do all 3 of these mean? (McCulloch manual said take to service center for adjustments but I figure I can do this myself.)

-- Also the priming bulb is cracked and won't hold fuel to prime with... any clue how to replace this ... or make it work?

Thx for any help. rlah
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post #2 of 7 (permalink) Old 04-09-2011, 05:11 PM
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T=?
H="High Speed"
L="Low Speed"

Are you sure the T is not maybe an I instead?

In any case, I suspect the T would be the Idle Stop adjustment, which basically just holds the throttle open to keep the engine running at Idle, screwing it in (clockwise) should increase the idle speed, while unscrewing (counter clockwise) will decrease the idle speed.

The low speed adjustment is a mixture adjustment, screwing it in (clockwise) leans out the mixture (less fuel) and unscrewing (counter clockwise) enriches the mixture (more fuel). The same holds true for the high speed adjustment screw.

The high speed is adjusted for high speed operation (cutting with full or partial throttle) and the low speed is adjusted for low speed (idle) operation.

Since your engine want's to die at idle, you may not be getting enough fuel at low speeds, you may want to turn the low speed screw out (counterclockwise) a 1/4 turn or so to see if that helps. It's also possible that your carburetor may need service and possibly new diaphragms to make it operate properly.
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post #3 of 7 (permalink) Old 04-09-2011, 10:15 PM
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You can go to this web site for a parts/repair manual for your saw.After opening,go to chainsaws/McCullough,Eager beaver2014.
Not 100% sure,but I think the"T" is for throttle(idle speed) as 30yeartech stated.hope this helps.

http://search.ebscohost.com/

Log in with:

Name: marshall

Password : public

Then select the small engine reference center icon.
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post #4 of 7 (permalink) Old 04-10-2011, 11:56 AM Thread Starter
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Thx to 30yearTech for your expertise. If I can, I'll let you know how my carb adjustments work out.

And thx to usmcgrunt for the location of the manual.

I'm ready to tackle this now.

I also found a parts list online in case I want to replace the primer bulb... or any other parts.

If I can, I'll let you know how my carb adjustments work out.

rlah
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post #5 of 7 (permalink) Old 04-19-2011, 02:32 PM Thread Starter
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After tearing into this unit, I found out that not only the primer bulb needed replacing, but also all the fuel lines which fell apart. So after getting all the parts (about $17 total) and following other threads here on fixing these items, I got it back together again. After a deep breath, I pulled the starter cord and after 1 or 2 tries, it started up and ran pretty well. So I wonder that the deteriorated fuel lines may have been the problem after all. But I played with the carb adjustment screws to optimize the idling.

Thanks to all!

rlah
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post #6 of 7 (permalink) Old 04-19-2011, 04:42 PM
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Good job on the trouble shooting and repairs.The fuel lines will have to be checked yearly as they have a tendency to dry out and crumble,as you found out.The newer yellow(Tygon)lines hold up much better than the old clear hoses.
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post #7 of 7 (permalink) Old 04-19-2011, 04:50 PM Thread Starter
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That's good to hear on the yellow lines... that's what the dealer sold me. Hopefully I won't have to look at replacing these for the life of this machine.

Thx! rlah
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