ButcherGY54
ArboristSite Member
I have a little McCulloch MAC 3516 that will just not quit. I bought this saw off a co-worker and it is a great little saw. I use it for limbing and for small firewood chores.
Well the other week I was bored so I took the Mac down into the basement and went to work. Tore it all down, cleaned it up and began to port and polish the ports and the lower crankcase housing. I opened the intake up to the point that when the piston is at TDC, the port is even with the skirt. I then lowered the port about .010" and also ever so slightly widened it. I also polished the intake but not to a mirror finish. The exhaust I widened and lowered so that when the piston is at BDC it is even with the piston top. I then mirror polished the exhaust port. The muffler has been modded for a while so there was no need to do more to it.
Then came the crankcase. It had a lot of casting marks in it. I know some will say they are needed to keep turbulence in the crankcase, but I do not. I polished the it smooth but not mirror finish. The transfers got a light filing and polish. I did not open them up or raise them. The top of the cylinder also received a polishing job to almost mirror finish.
There was no gasket between the jug and case when I took it apart. Just gasket maker sealant, so I did the same. I then noticed that the screw holding the butter fly to the carburetor shaft was sticking into the airway a lot. I filed the threaded part down even with the shaft, and filed the head down a little also. I put it all back together with the coil in the same spots as when I took it apart. The coil has slotted mounting holes to adjust the timing.
Let me tell you something. This little monster really rips now! I can bury this thing and it just keeps cutting. The only way I can get it to bog down is if I really lean on it. I do not believe how much of a difference this has made. I can not wait to tear into my 025 and see what I can play with.
David
Well the other week I was bored so I took the Mac down into the basement and went to work. Tore it all down, cleaned it up and began to port and polish the ports and the lower crankcase housing. I opened the intake up to the point that when the piston is at TDC, the port is even with the skirt. I then lowered the port about .010" and also ever so slightly widened it. I also polished the intake but not to a mirror finish. The exhaust I widened and lowered so that when the piston is at BDC it is even with the piston top. I then mirror polished the exhaust port. The muffler has been modded for a while so there was no need to do more to it.
Then came the crankcase. It had a lot of casting marks in it. I know some will say they are needed to keep turbulence in the crankcase, but I do not. I polished the it smooth but not mirror finish. The transfers got a light filing and polish. I did not open them up or raise them. The top of the cylinder also received a polishing job to almost mirror finish.
There was no gasket between the jug and case when I took it apart. Just gasket maker sealant, so I did the same. I then noticed that the screw holding the butter fly to the carburetor shaft was sticking into the airway a lot. I filed the threaded part down even with the shaft, and filed the head down a little also. I put it all back together with the coil in the same spots as when I took it apart. The coil has slotted mounting holes to adjust the timing.
Let me tell you something. This little monster really rips now! I can bury this thing and it just keeps cutting. The only way I can get it to bog down is if I really lean on it. I do not believe how much of a difference this has made. I can not wait to tear into my 025 and see what I can play with.
David
