Muffler Modding older Macs

[martyinmi]

I have a few "middle aged" Mac's that I really like- Pro Mac 555, 700, and 850.
I've bragged to a few of the guys I hang around with that the 555 will easily run with, and even possibly out run my Stihl MS 310 (in bigger rounds).
Today after unloading a few 18" Ash rounds I figured I'd add some legitimacy to my braggin' by doing a few timed cuts with both saws.
I just knew that the 555 would cut measurably quicker than the 310 in larger diameter wood.
IT WILL NOT!  :-[ There is no measurable difference between the two.
The 310 will cut 10" and under slightly faster than the 555. I guess I kinda seen that one  coming. :-\
I did a you tube inspired muffler mod a few years back on the 310. In the same piece of wood it cut roughly 5% faster after the mod, so I'm a believer that muffler mods work.
So I guess my question for you all is this: Will a mod work on the 555? And...how would I do it. The exhaust comes off the cylinder on the bottom and vents out the right side(that is the side the passenger sits on unkie Al ;D), so would it help to drill another hole in the muffler and vent some gasses out the bottom too? Or would that pose a fire risk?
I just can't imagine how or why a mod would help it. It is SO LOUD as it is. But does loud always mean more power?

All I'm hoping for is just a half second quicker than the 310...???

By the way, those older Macs are LOUD? :D

[AKDoug]

The two are basically the same size engine saw.  Most older saws don't benefit from a muffler mod like a modern saw does.

[MidWestTree]

Anything you may gain by further mods to that Mac muffler would probably be so slight you wouldn't be able to tell a difference.

[AdkStihl]

Most Macs need a reverse muffler mod......  :D

[MidWestTree]

Yep, that's pretty much spot on they breathe easy enough without any help. For getting the most out of an older saw that pre-dates EPA restrictions an experienced ear or tachometer is your friend, tuning is where it's at.

[AdkStihl]

Don't tune an old saw with a tach!! Your ear is all you need  ;)

[Al_Smith]

Anything you may gain by further mods to that Mac muffler would probably be so slight you wouldn't be able to tell a difference.

To a point correct  but not all the time .

I gotta come to young wayward nephew Marty to help him out here .The 10 series and all Macs use a baffled muffler not a pressure can .Some of this series has a square ended discharge straight down from the cylinder and a 90 degree turn up on the discharge .

[Al_Smith]

This is going to take a long while because it times me out but bear with me .Now then just like an air conditioning duct a bunch of turns in an exhaust causes bad pressure .Some of the ten series used a rounded discharge from the cylinder and a straight out discharge with a large area where the baffle plates go .Find one of those .Probabley an early 10-10 .

Remove the screen,baffle  plates just leave the outer deflecter .Now see how it runs and don't get stingy with the high speed jet ,give it some fuel and for heavens sakes wear good ear muffs because ear plugs won't get it .

[Al_Smith]

Now the 850 .If it's an older style with the large muffler do the same .If it's a later model with the wire discharge find an earlier model muffler .

Some people are under the misconcieved idea the ten series can't still hold their own against a modern saw .Well guess what I have a 70 cc 6-10- that will free rev at 15,600 RPMS and still be 4 stroking .It's been enhanced a tad bit though with some exhaust port work and a larger carb plus a muffler with a rounded discharge .Timing set at around 30 advance

At the last GTG it was running heads up with a Huskey 372 . 8)

[Al_Smith]

Bottom discharge ,bad plan .You'd have to cut the bottom out of the handle .Either Randy Mac or "bowsaw "Cliff told of doing so and it blowed stuff all over the place plus about burnt their leg off .

Now Big Dave Neiger had a piped 550 Homelite which is a bottom discharge and he had a stingerless tuned pipe on it .Looked odd but ran good .I had my hot little hands on that one too .

[motard]

Old Macs,

most are 'clamshell' designs.

I did a 7-10 a few years back to burn e-85, she idles wonky (metered de-comp) but will pull a 28" through hardwood like it's a 6 cube!

[Al_Smith]

Lawdy that dome would about smother the combustion chamber .

Earth to Marty .Surf flea bay using the criteria of McCulloch muffler ,850,700 ,10-10 .You can see the difference I refered to as curved bottom style as oppossed to large internally baffled types used on later models.

I might add some models of the ten series used a muffler with a spring loaded door .I suppose it was to emulate a "power valve " used on dirt bikes .

Typical of the drunkin stupor the design engineers were in in the late 70's it didn't work .Rusted shut tight as a bulls behind during fly time .If you have one of those grind the door hinge off if you want it to run good .

[motard]

Lawdy that dome would about smother the combustion chamber.
Earth to Marty .Surf flea bay using the criteria of McCulloch muffler ,850,700 ,10-10 .You can see the difference I refered to as curved bottom style as oppossed to large internally baffled types used on later models.

I might add some models of the ten series used a muffler with a spring loaded door .I suppose it was to emulate a "power valve " used on dirt bikes .

Typical of the drunkin stupor the design engineers were in in the late 70's it didn't work .Rusted shut tight as a bulls behind during fly time .If you have one of those grind the door hinge off if you want it to run good .

Yeah I overdid it eh?

That is why it has a metered de-comp, otherwise she acts like she's hydro-locked!

[Al_Smith]

Well I've got an SP-81 that had a weak decomp that closed on me at a very inoperatune  time and
"Climbed " the rope .Lucky it didn't fire .I never again drop started that saw .Too close for comfort .Stupid any way ,drop starting a 5 cubic inch saw with a 28" bar like I was Paul Bunyan or something ,dumb .

[motard]

I can relate,

No spring chicken here, have a 143 SD that I put a 55mm Mako domed piston fer a 152/153.

Broke the rope so many times had to go bigger, it only holds about 15" now.

You better be serious as a heart attack when you pull that one over!

[Al_Smith]

 :D Well yeah I preach all the time do not play patty cake with a souped up saw .Pull that thing over like you mean it .If you don't it will try to pull you through the recoil .

[motard]

Yup they bite back like they have an agenda eh?

[Al_Smith]

So here comes nephew Marty with a big question and then he goes AWOL  ???.He probabley got buried under the snow,Michigan gets a lot of it .

[martyinmi]

So here comes nephew Marty with a big question and then he goes AWOL  ???.He probabley got buried under the snow,Michigan gets a lot of it .

Didn't mean to bug out on ya'll uncle Al.
Life sometimes gets in the way of my playing sometimes.
Waterers freezing up at work, stupid employees breaking things that should be nearly unbreakable, lagoon pumps letting me know in no uncertain terms they do not care for a foot of ice, etc.
At least one indoor soccer game (usually two-my son is one of the better U-12 players in the state, so he practices with U-13 teams all winter) every weekend.
I did manage to haul the 555 to work last Friday. It's in the heated shop, so as soon as I get time I'll......I'll probably have another soccer game or another catastrophe of some sort at work.  >:(
Oh well, at least it'll be warm!

And for what it's worth...I wouldn't trade my life with anyone! I am the most Blest (or is it Blessed) man on this planet!! 8)

Maybe I'll skip lunch tomorrow and do some ripping and tearing and picture taking and see what cha'll think!  Maybe!

 

[Al_Smith]

Yeah I'm with you nephew .The older I get the less I like cold weather .If my deceased father had his way I would have been born in Alaska .My mother put a stop to that .This time of year Florida is looking pretty good .

[martyinmi]

Well, I tore the muffler apart on my 700 a few days ago. There wasn't any screen in it.
There WAS a plate(baffle?) in there about 2" long and 1 1/4" wide with three holes in it that I took out and promptly misplaced. It had a portion of it's corner either eroded or broken off.
I wish that I had done a few before/after timed cuts to see if removing it helped. It definitely helped in making it louder. _earmuff
I think I've got the old feller at work (he's uncle Al's age :D) talked into bringing his J-red 2172 in to do a bit of side by side cutting on a few 20" dead Ash I pulled out of the woods last week. The last time we played together with these two saws the old Mac easily out ran the 2172(2 or 3 seconds quicker through a 18" Ash). He's had his back to the dealer a time or two trying to get a few issues he's had with it ironed out.
Give ya'll my report later on in the week! ;)

[ladylake]

 
No matter how many kazillion RPM the new saws turn the old ones cut good.   Steve

[mad murdock]

Better git yer friend outfitted with some good ear protection, the exhaust reed broke on my PM700, and when it did, man was it loud!!! Didn't notice any improvement in performance, it cut like a banshee either way, just sounded a LOT louder with the broken reed.

[Al_Smith]

That muffler cover with that spring loaded trap door didn't work so well any way .You're better off without it .

[Al_Smith]

Now as far as a 700 if it's properly tuned it might not outcut a  modern 70ish cc saw but it won't be far behind it .

I think it was two years ago in 96 degree weather I was using a stock Stihl 038 mag and alternating with one of my 700 Macs .My only compliant in that heat when I shut the Mac down to refuel it that pot licker would not start and the Stihl would .This time of the year it would not be a problem.

[martyinmi]

Well, my poor old 700 dun got a good 'ol fashioned butt whoppin' today. :embarassed:
His 2172 is finally running good after a few warranty visits back to his local dealer.
We both made around 40 cuts through 4 different Ash trees. In the smaller trees (15" and under) my 700 didn't stand a chance. The chain speed on the re-badged Husky is WAAAY faster than the 700's. If we had nothing to cut but trees that small I'd dare say that I'd only buck 4 pieces to his 5...maybe even less. :'(
I did beat him in the largest tree, which was a bit over 22". His just blasts through the first 5 or 6" while mine is barely through the bark, but when his gets about a third of the way through, mine will quickly catch his and pass him. 8)
I don't know anything about the drive sprockets on the older Macs, so I'm hoping you guys do. Can I put a larger drive on it to pick up some chain speed?
The old guy I was cutting with actually had that suggestion. He didn't think there'd be squat for difference in the two saws if I could just get pull my chain faster. He even admitted that in 24" wood with the appropriate bars the Mac would beat the Jonsered every time.
However, the day went to him and his 'Red. He whipped me in about 35 of the 40 cuts we made.
That'll be the LAST time I sharpen his chain and trim his rakers! >:(
 

[Al_Smith]

It depends nephew .You can hang an 8 tooth rim on it and see how it goes .I assume it has a rim drive ?

The 700 will have the torque but the Husqvarna will have the rpm's .

Now what you could do is find another key for the flywheel and file part of the back of so you can rotate the flywheel ahead about 3 degrees and advance the timing  a tad bit .Might work ,if not put the other key back .