Another tuning thread

[2broke2ride]

Sorry to ask again but just trying to get a solid answer.
I'm struggling to tune my Mac 380 (see the plug pic thread)
My question pertains to tuning "in the wood".
Can I just tune for max rpm under load in a cut? If I do that it is a bit leaner than I am set right now and I don't notice the four stroking unloaded that I'm used to with more modern saws. Maybe that's ok with these oldies? I don't know.
I wanna make this saw run as best I can and I don't want to burn it down trying.

 

[blsnelling]

Just make it so rich that it won't clean up in the cut. Slowly lean it out until it will. That's a good safe tune.

 

[2broke2ride]

I've tried it that way and it seems really down on power. If I lean it out past that it really comes alive in the wood but I don't notice any fourstroke unloaded. Maybe it's there and I just don't hear it. I posted a video in the Mac thread and everyone seemed to think it was down on power as did I.
I will add that I had to richen almost a full turn from the book setting to get a noticeable fourstroke and according to the book that's too much. It says the baseline should be within a half turn either way.

 

[jr27236]

Forget the book lol. Tune by ear, till it four strokes and then back in until it just cleans up. That should do it, but every saw is different and how old, clean,dirty or worn your carb is also will make a difference. So if your book says one turn out as a baseline and your two out to make it four stroke and then come in a 1/4 - half in the wood to get max rpms, your still above your baseline and richer fuel wise then the stock setting,(which are mostly too lean anyhow). So count your turns in until you screw (just sets) and see where she is and then you can always come back out to that point and fine tune from there. If your carb is old and not a recent rebuild, your gonna have a hard time getting a proper tune, sometimes almost damn impossible.

 

[2broke2ride]

Carb is freshly rebuilt and saw has new crank seals.
These saws have huge Venturi in the carb compared to a modern saw and zero restriction in the "muffler" I wonder if that contributes to it not being easy to hear the fourstroke.

 

[jr27236]

Well as long your definitely not leaning her out, you should be ok.
I would think youd hear it or at least it would want to start to die when open to much. Are you open beyond factory settings as is?

 

[2broke2ride]

Well as long your definitely not leaning her out, you should be ok.
I would think youd hear it or at least it would want to start to die when open to much. Are you open beyond factory settings as is?

Yes, took almost a full turn out from factory setting to get a noticeable fourstroke. The book says the factory setting should get it within 1/4 turn either way. It seems way down on power in the cut. If I lean it out and get a little closer to the factory setting it has good power but doesn't fourstroke when unloaded.

 

[Marshy]

Can you post us a video of you cutting with it?

Its kind of hard to explain in typing but once it stops 4-stoking in the cut and cleans up, the leaner you tune it the easier it will clean up (stop 4-stoking) in the cut. Meaning it will stop 4-stoking with a lighter load on the chain like cutting a small limb vs a heavy load like having the bar buried. Its best to start the tuning with the bar buried though. Hope that makes sense.

 

[2broke2ride]

Only vid I have right now, I've messed with it quite a bit from this but you can hear the fourstroke and also see how down on power it seems, sorry about the shaky video, my 9 year old took it.

 

[Marshy]

The good news is its not 4-stroking in the cut. I can clearly hear it 4-stroking then clean up as soon as you enter the cut at 00:07. Could it be leaned out some, possibly but I cant say just from what I see there, I'd need more info. How much compression does it have? What does the plug look like?

How large of a bar is on that saw? Its only a 38cc saw and it seems to be laboring kind of hard in that (15"?) round. What chain are you running on it? Whats your rakers set at? Maybe the chain is a little aggressive and bar a little long for it?

 

[2broke2ride]

The good news is its not 4-stroking in the cut. I can clearly hear it 4-stroking then clean up as soon as you enter the cut at 00:07. Could it be leaned out some, possibly but I cant say just from what I see there, I'd need more info. How much compression does it have? What does the plug look like?

How large of a bar is on that saw? Its only a 38cc saw and it seems to be laboring kind of hard in that (15"?) round. What chain are you running on it? Whats your rakers set at? Maybe the chain is a little aggressive and bar a little long for it?

That, my friend, is an 87cc saw[emoji12][emoji106] circa 1960s
The bar is 28" the chain is 3/8x.058 full chisel full comp, brand new untouched maybe 10 cuts on it.
The saw has 120psi on my Mac tools gauge.
McCulloch manual says 90 psi is minimum

 

[2broke2ride]

I have another thread about the plug.

 

[Marshy]

I have another thread about the plug.

Post the link!

LOL I googled MAC 380 and got McCulloch Power MAC 380...
http://www.acresinternet.com/cscc.n...16d9fed8dd1b2ad488256c2f001b6b7a?OpenDocument

 

[2broke2ride]

Can't figure out how to post a link, it's on here titled "tell me about this plug" here are the pics, plug is very ashy and gray.

 

[2broke2ride]

Post the link!

LOL I googled MAC 380 and got McCulloch Power MAC 380...
http://www.acresinternet.com/cscc.n...16d9fed8dd1b2ad488256c2f001b6b7a?OpenDocument

I bumped the thread for you

 

[Marshy]

You should consider replacing that plug IMO.

 

[2broke2ride]

No time to mess with it tonight, just got home. I did put a new plug in it yesterday and I think I have it running pretty well. Although I'm still not sure I can hear it fourstrokeing, I tuned it to have good power in the cut.

 

[stihl041avhog]

Just make it so rich that it won't clean up in the cut. Slowly lean it out until it will. That's a good safe tune.

if air tight yes listen to it but put it wood/load

 

[2broke2ride]

if air tight yes listen to it but put it wood/load

Not sure I'm understanding what you are trying to say here.

 

[burnses]

always tough to tune by pictures and video but the plug has a lot of build up almost looks like the saw has been run on leaded fuel for awhile....I would start with a new plug and from where your H setting is now lean it out just a bit 1/16 of a turn and see if the power comes up does seem to be on the rich side in the cut. If the power improves tune to your best power and then make it richer a bit look at the plug as you go but its hard to read a plug with todays unleaded ethanol fuel but I think the tune you will end up with will be a shade lighter than your posted picture particuraly at the edge of the insulator....good luck