McCulloch maccat 330


Old 11-18-06, 07:50 AM
Thread Starter
Join Date: Nov 2006
Location: infront of my pc
Posts: 3
McCulloch maccat 330

Hi all,

Nice forum. Forrestry is not my trade but I just wondered if somebody might be able to help me. I have a maccat which is running rough. I have cleaned the air filter and changed the plug. I think it needs a bit of a tune up but I wondered if there was a service manual available for this model. I bought the saw secondhand and it had no manuals with it.

On top of the carb are 3 screws, hi, low, and idle. If a muanual is not available I wonder if maybe someone could help me with some advise on how to tune it. I am a car mechanic by trade so I understand engines, carbs etc. I have tried to tune this saw by twidling the screws until it sounds right. This is great until i try to start it! I then have to retune it until it starts and gets up to temperature then tune it until it runs right!! This is getting annoying - I just want to be able to get the saw out and use it not spend 2 hours getting it to run right then use it for 10 minutes to cut some logs!! The ammount I use the saw it would take less time to use a bow saw!!

Thanks in advance.
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Old 11-18-06, 08:38 PM
30yearTech's Avatar
Join Date: Oct 2006
Location: Central Texas
Posts: 1,176
There is a good chance that the diaphragms in the carburetor are stiff and need to be replaced, having to readjust all the time is a good indicator of this. Check the fuel filter and fuel lines and make sure they are all in good order.

The saw should start up fairly easy with High and Low speed adjustments set at 1 1/2 turns from seat. You will have to fine tune after engine is warmed up, but you should not have to repeat adjustments once set. Also make sure the fuel mix is fresh as stale fuel will affect adjustments.
Old 11-19-06, 01:43 AM
Bigwind's Avatar
Join Date: Nov 2004
Location: The Panhandle of Florida
Posts: 167
30 Year Tech is right on the money! I also think you'll need to rebuild the carb. Being a mechanic you probably know this already but I posted it recently and I'll just paste it here for your use...IF NECESSARY...You may find a review of how to rebuild a two cycle carb useful. Go to the Walbro or Zama websites (Doesn't really matter). You can then navigate to a ton of information about Carburetors in general that will help you a lot. Tillotson also has some info? Just be real careful taking the carb apart and you'll have no problem replacing everything correctly. You'll find the info you need to identify and then cross reference your carb STAMPED (Not Molded) into the body of your carb. You may need a magnifying glass to find it, but it's there. The kit will cost between $7 and $15??? If you have a problem cross referencing for the proper kit post your carb's info back here and someone will help you!

TWO CRITICAL THINGS: 1) When you remove the screw holding the valve arm keep your finger over the lever arm. Release it slowly and carefully and do it upside down over a soft white cloth. The spring underneath the arm is very small and you don't need to loose it as another one is typically NOT in the rebuild kit. 2) Be sure to remove the screen that will be pushed into a circular depression. You often find particle behind it even though it looks clean from above. Careful not to damage the carb. A replacement screen is provided in the kit (TIP: The longest needle valve is the LOW valve).

Again, if necessary here is HOW TO TUNE the carb / engine after you rebuild it: Turn both needle valves on the carb to the right until they LIGHTLY seat.(DO NOT OVER TIGHTEN) Then turn them both out 1 11/2 turns. All engines will usually crank at this point but you may have to play with the throttle to keep it running. Let it warm up then turn the low valve with the (L) beside it to the RIGHT until the engine starts to run rough. Turn it back to the LEFT until it starts running rough. Then set this needle to the mid point. NOW set the high valve with the (H) beside it. Give the engine full throttle and do the same as above. Turn to the Right until it falls off and back to the Left until it falls off. Set it to the mid point. You can then turn it slightly to the RIGHT and you'll get higher RPM's but be careful because you are leaning it out and it is getting less oil. The engine will fail if you leave it like this so be careful to turn the valve back to the left a quarter turn or so from it's best running point. Good luck, Ron
Old 04-19-10, 10:44 AM
Thread Starter
Join Date: Nov 2006
Location: infront of my pc
Posts: 3
How rude of me not to reply sooner, sorry I just forgot. Thanks for the advise, it turned out in the end to be as simple as perished fuel lines, I replaced them and it ran fine after.

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