MAC Question

[THALL10326]

Thanks

LOL! though....easier said than done, as the spark plug is mounted at an angle to the stroke of the piston.

Anyways, after numerous attempts to measure (and tossing out the wishful thinking in interpreting the results) it appears to be the 80cc version, as the stroke appears to be closer to 1 3/8" rather than the 1 1/2" required for the 87cc version.

In all actuality I suspected as much, as I had pretty much settled on the saw being this variety from circa 1970:
http://www.acresinternet.com/cscc.n...5fa50a1b8855469b88256c2f001aa843?OpenDocument

Thanks again for your help

Sap can't help but notice your getting the chain saw fever. Your building a collection of saws now, cool. That old Mac looks like a beast of a saw. How much does that big saw weigh??

 

[coveredinsap]

Sap can't help but notice your getting the chain saw fever. Your building a collection of saws now, cool. That old Mac looks like a beast of a saw. How much does that big saw weigh??

I don't know...I'm guessing around 20lbs or so.

And this makes #8 now....yikes!

 

[THALL10326]

I don't know...I'm guessing around 20lbs or so.

And this makes #8 now....yikes!

lol, 8 huh, I knew it,lol. I got a old Mac 35 out in the shed made in 1949. Still runs beleive it or not. Feller gave it to me. Your Mac looks huge and should tear up some big wood. Beware, your at 8. When I had 3 or 4 I thought that was plenty. I got 20 now so beware, the saw fever can become a lifetime hobby........

 

[coveredinsap]

I'm wondering if I can replace the existing 1 3/8" stroke piston setup on this Mac with the longer 1 1/2" stroke piston?

And is their a source for for the parts necessary to complete the job?

 

[THALL10326]

I'm wondering if I can replace the existing 1 3/8" stroke piston setup on this Mac with the longer 1 1/2" stroke piston?

And is their a source for for the parts necessary to complete the job?

That would be a major undertaking Sap. Would have to change the jug for sure and maybe the crank if the rod is built onto it like Stihl cranks are.

Theres a guy in the hot saw section that deals only in Macs. He'd be your source for Macs. They are the only saw he deals in and I've read some of his posts, he knows his Macs.........

 

[coveredinsap]

That would be a major undertaking Sap. Would have to change the jug for sure and maybe the crank if the rod is built onto it like Stihl cranks are.

Theres a guy in the hot saw section that deals only in Macs. He'd be your source for Macs. They are the only saw he deals in and I've read some of his posts, he knows his Macs.........

Well that shoots the sheet out of that. I was thinking if I needed to replace the piston rings I could swap out the setup for the longer throw while I was at it....but it doesn't sound like that is the case.

 

[Lawn Masters]

Its tricky to do this mainly because the crankcase, and cylinder are one piece, the crank slides in through the flywheel side I think. you could put the longer stroke setup in, but it'd stop dead in its tracks pretty fast.

 

[THALL10326]

Well that shoots the sheet out of that. I was thinking if I needed to replace the piston rings I could swap out the setup for the longer throw while I was at it....but it doesn't sound like that is the case.

Well to be honest, as big as that saw looks I'm sure it has plenty of power just the way it is. I see now you got the saw fever more than just collecting some saws and I say cool. Its a neat hobby...............

 

[Paul61]

I'm wondering if I can replace the existing 1 3/8" stroke piston setup on this Mac with the longer 1 1/2" stroke piston?

And is their a source for for the parts necessary to complete the job?

Sap, in order to obtain the larger cc engine size, (by stroke only) just swaping the piston won't work.
You need to change to the 1 1/2 stroke crank and also use the piston from that set up. The piston has a higher pin placement to allow for the additional stroke, so that it won't crash into the plug end of the cyl. bore. The extra cc's are obtained by a lower bottom dead centre position of the piston in the cyl.
I believe Lawn is saying that the larger crank setup may not fit your crankcase?

You may be able to approx. (scale) the existing stroke by removing either the muffler or carb. & viewing the piston?

Paul

 

[spike60]

Neat saw! And some good pics.

What does that thing sound like?

 

[RaisedByWolves]

Before than doing a build on the engine I would first switch this over to .375 round ground chisel.


Most likely this saw is a torque monster and you then could lean on it harder or lower the depth guages some to get it to cut faster.

 

[coveredinsap]

.....I believe Lawn is saying that the larger crank setup may not fit your crankcase?

Thanks, I got that part

You may be able to approx. (scale) the existing stroke by removing either the muffler or carb. & viewing the piston?

I don't know what you mean by this part though.

Neat saw! And some good pics.

What does that thing sound like?

Thanks

Actually it doesn't sound too bad, which is rather surprising for that little muffler. Or maybe I'm just going deaf...even with the earplugs

 

[Lakeside53]

Piston goes up - Bang - piston goes down

Actually, nice pic ULtra! I need one at work to explain to customers that really want to know..

 

[Old Mac Guy]

.... I got a old Mac 35 out in the shed made in 1949. Still runs beleive it or not. Feller gave it to me.

Thall, do you mean a 3-25??

 

[coveredinsap]

]


Sap this is what Paul is saying ..You might be able to measure stroke through the port as piston goes up and down..

Uh, yeah...duh. I already did that earlier. Have you read the whole thread? the piston stroke is 1 3/8". How does what you are saying now change anything?

The question was will the piston setup with the longer throw (1 1/2") fit into this saw. The answer appeared to be 'no' ....because the piston with the longer throw requires a different crank, a crank that would bottom out on the floor of the crankcase.

How does what you are saying change any of that?

 

[sawinredneck]

Thanks, I got that part

I don't know what you mean by this part though.QUOTE]

What they are trying to illistrate is how to "scale" the piston movement by removing the muffler or carb. You use a machinist scale to measure the pistons travel with either of them removed to obtain the stroke.


Andy

 

[coveredinsap]

What they are trying to illistrate is how to "scale" the piston movement by removing the muffler or carb. You use a machinist scale to measure the pistons travel with either of them removed to obtain the stroke.


Andy

And what does that method get me exactly ...that the wire thru the spark plug port trick couldn't? The stroke is now 1 3/8". What more do you need to know?

 

[coveredinsap]

Thanks again Mc Bob for the wire thru the spark plug hole trick to measure the piston's stroke.

Not only was it a neat trick, it was evidently a new one on the johnny-come-latelys posting pictograms to this thread also. 'Machinists scale' indeed! LOL!

Thanks

(By the way, wtf was up with the after-the-fact pictogram post and comments? I said I wasn't an engine specialist, not that I didn't know anything about engines. Jeez Louise already.)

 

[Paul61]

I'm not an engine specialist....is there a way to measure the stroke without removing the head?

Are you not aking how to simply measure the stroke here?

I'm wondering if I can replace the existing 1 3/8" stroke piston setup on this Mac with the longer 1 1/2" stroke piston?

My reply to this was to clarify that "just" a piston swap, as in your post, will not give you the stroke increase you desire.

Jeez Louise

Relax Sap, we're just tryin to help.

 

[Lakeside53]

Why bother trying to increase the stoke/bore anyhow.. Just buy another with the right parts - they aren't rare and sell for free up to $50..