McCulloch Chain Saws

[Jethro 2t sniffer]

That would sure be handy for us saw hoarders

Hell yeah some 70cc be good too please and thank you

 

[vizette]

Sawzilla has an AM oil seal set, fwiw....

https://www.ebay.com/i/223184308735...MIjfHf9rX16QIVkobACh0gtQbuEAQYASABEgL8nfD_BwE

I just picked that up not long ago, but have yet to use it - have you used that before? What I've seen from sawzilla so far has been decent so I'm hoping this is too.

 

[Max the Mac Man]

I was talking to a Mechanic I know yesterday, and found out his hobby is old saws too. We got to jawing and got on the fuel and oil topic. He told me something that has got me wondering. He is mixing 101 octane racing fuel (it has lead in it) with Stihl oil in his vintage Stihl saws. He said they run well on it and problems with fuel sitting in them have vanished. What you guys think about using 101 octane racing fuel in the old Macs? Part of me wants to try it. Part of me is hesitant. I don't want to hurt or blow a saw.

Max

 

[Brian Thacker]

Race fuels are very pure. Your friend is right they do not varnish up like pump gas. I have not bought race fuel in a long while but at one time you could get 96 octane. Find a Klots, VP or Shell dealer and they can tell you better about there products. When I was racing I used to buy a 55 gallon drum of 114 fro, Klots. Used to run it in my lawn mower, weed eaters and such all the time. Get up on a Saturday morning to mow and not feel like running to the store to get fuel and just use that. I never had any problems with it. This was over 20 years ago and I still have the same mower, weed eater and blower and still use them except no race fuel any longer.

Brian

 

[vizette]

I was talking to a Mechanic I know yesterday, and found out his hobby is old saws too. We got to jawing and got on the fuel and oil topic. He told me something that has got me wondering. He is mixing 101 octane racing fuel (it has lead in it) with Stihl oil in his vintage Stihl saws. He said they run well on it and problems with fuel sitting in them have vanished. What you guys think about using 101 octane racing fuel in the old Macs? Part of me wants to try it. Part of me is hesitant. I don't want to hurt or blow a saw.

Max

I've considered doing something like this as there is a Sunoco down the street that sells a variety of gas in large-ish cans (5 gal?) and that's the only source of non-ethanol gas around here, aside from like trufuel or something from the big box. I want non-ethanol for exactly the reason you mentioned - sitting fuel causing issues. I wouldn't see a need for a high octane unless you were running a crazy compression saw though?

 

[PogoInTheWoods]

I just picked that up not long ago, but have yet to use it - have you used that before? What I've seen from sawzilla so far has been decent so I'm hoping this is too.

I've only used OEM seals on my Mac projects but have used other products from Sawzilla with no issues.

 

[rwoods]

Lead may be good for your saw’s longevity, but not sure about yours if you run it a lot. Ron

 

[Jethro 2t sniffer]

So have a bit of run time on the hot rod project 700. Had both the tweaked and standard 700's running together, and picking up in turn cut on cut to get a feel for what the result was.

To recap I have extended the intake timing to 140' of duration, tided up and blended the various steps in the intake and similar on exhaust side. No changes to transfers to exhaust timing, no other changes to the rest of the saw.

The changes are subtle, the Mac character remains. Maybe a little loss in torque right down, but difficult to be sure. No loss in the working range. Both saws running same bar length and both on 3/8 chisel chains in a slightly hungry raker state. A definite increase in top end speed. The hot rod saw runs at a guess ~500 rpm faster in its happy working spot. Idle unchanged, no spit back or oil deposit in air box. Power increase - yes. Not mind blowing, but unmistakably stronger.

I am happy - I suspect next move is exhaust on this power quest.. That outlet from the head is awkwardly tight. Not going there right now, too busy and cutting done for this season pretty much.

Last point, fuel consumption. Both tanks emptied together so no negative on the hot rod. 700's use much more fuel than my 555 which gets noticeably more work done on a tank.

Roland.

Hey Roland how did you get that duration? You were talking about shaving the piston skirt a while back

 

[MacAttack]

I was talking to a Mechanic I know yesterday, and found out his hobby is old saws too. We got to jawing and got on the fuel and oil topic. He told me something that has got me wondering. He is mixing 101 octane racing fuel (it has lead in it) with Stihl oil in his vintage Stihl saws. He said they run well on it and problems with fuel sitting in them have vanished. What you guys think about using 101 octane racing fuel in the old Macs? Part of me wants to try it. Part of me is hesitant. I don't want to hurt or blow a saw.

Max

The big difference is probably the lack of ethanol in the race gas. Not as much the octane or lead.

I can fortunately can get non-ethanol where I live. No fuel-related issues.

 

[Max the Mac Man]

I've considered doing something like this as there is a Sunoco down the street that sells a variety of gas in large-ish cans (5 gal?) and that's the only source of non-ethanol gas around here, aside from like trufuel or something from the big box. I want non-ethanol for exactly the reason you mentioned - sitting fuel causing issues. I wouldn't see a need for a high octane unless you were running a crazy compression saw though?

I have non ethanol 93 now. Just unleaded. The racing fuel has lead in it. All my saws are are or were built back stock. I want longevity more than the fastest rpms, and torque. My 82cc saw have all I need stock lol.

Max

 

[heimannm]

McCulloch recommended against the use of leaded fuels, they show illustrations of "lead balls" forming on the tips of the spark plugs shorting out the electrodes. I have actually seen this happen twice on the same old saw - my 2-10G - had to pull the spark plug and clean the electrodes to keep it going. Once I started running my own modern fuel I never had the issue again. They also recommended 70 octane gasoline. Higher octane does not have more energy, actually a little less, but does allow you to operate at much higher compression ratios without having preignition or knock issues. Not an issue on the saws since the stock versions are all in the 6-7:1 compression ratio range.

Keep your fuel fresh and use ethanol free if you can get it. If you must use ethanol blended fuels be sure to run them out when you are finished with the saw and even consider leaving the gas cap off for a day to dry the tank completely if you are worried about corrosion in the older saws with aluminum and magnesium fuel tanks.

Mark

 

[Jethro 2t sniffer]

The whole higher octane thing is a bit of a myth really. Like yes a modern car runs a bit better on it but not because of more energy like you said Mark but simply the ECU hears less knock so can up the state of tune a little.

 

[mogulmasher]

Right higher octane had a slower colder burn. Engines run best on the octane they were designed for, higher does nothing.

 

[vinnywv]

Lots of octane talk on the web. Its odd we dont want ethanol but we want higher octane. But ethanol is used to raise octane in fuel. So the higher octane rating the more ethanol in the fuel. Unless its non ethanol fuel of course. Then they use different things to raise octane ratings. Stihl for example "recommends" higher octane fuel. And they tend to have more carburetor issues that i read about. Personally i stick with 87 octane fuel in my 2 strokes. Never had an issue. I dont have non ethanol fuel readily available so i use 87. Lowest ethanol available.

 

[Maintenance supervisor]

We have ethanol free gas available in SC so I run that, for obvious reasons.
The primary reason lead was a benefit ,was the valve seats in vehicles were not hardened universally until about 1973, lead helped the valve seats and stems.(long explanation can be found elsewhere)
Chainsaw no valves, so no lead needed.
As far a octane rating needs? It is true that the requirements for a chainsaw are pretty low, but higher octane is less prone to pre-detonate from a cylinder hot spot than low octane , carbon of any kind in your cylinder becomes a hot spot causing a burn before ignition event . In that situation the preignited fuel causes more carbon to build and rocks the piston in the bore due to an uneven flame umbrella, its why we have spark screens, preignited carbon becomes super heated and breaks off in the preignited event.
I add octane boost to all my small engine gas or use the highest available because once you add mix oil to that gas you change the octane rating. Starting with 87 and adding a 32:1 or 40:1 organic based oil is gonna drop it to 76-70 octane which is right in line with Mccullochs recommended octane rating. Personally I'm concerned about the carbon hotspots ,so I use synthetic mix oil and a higher octane for complete uniformity of burn.
I would NOT recommend lead for a non valve engine, or using AV gas because it has a deicng agent in it that can mess with burn uniformity at normal temperatures.
This is all just personal preference for me though ,heck I'm sure there's plenty of old saws that were run using the cheapest gas and 30wt oil for years.

 

[Max the Mac Man]

McCulloch recommended against the use of leaded fuels, they show illustrations of "lead balls" forming on the tips of the spark plugs shorting out the electrodes. I have actually seen this happen twice on the same old saw - my 2-10G - had to pull the spark plug and clean the electrodes to keep it going. Once I started running my own modern fuel I never had the issue again. They also recommended 70 octane gasoline. Higher octane does not have more energy, actually a little less, but does allow you to operate at much higher compression ratios without having preignition or knock issues. Not an issue on the saws since the stock versions are all in the 6-7:1 compression ratio range.

Keep your fuel fresh and use ethanol free if you can get it. If you must use ethanol blended fuels be sure to run them out when you are finished with the saw and even consider leaving the gas cap off for a day to dry the tank completely if you are worried about corrosion in the older saws with aluminum and magnesium fuel tanks.

Mark

Thanks Mark! Good info. I appreciate it, you, the others here, and the knowledge in the thread.

 

[Max the Mac Man]

We have ethanol free gas available in SC so I run that, for obvious reasons.
The primary reason lead was a benefit ,was the valve seats in vehicles were not hardened universally until about 1973, lead helped the valve seats and stems.(long explanation can be found elsewhere)
Chainsaw no valves, so no lead needed.
As far a octane rating needs? It is true that the requirements for a chainsaw are pretty low, but higher octane is less prone to pre-detonate from a cylinder hot spot than low octane , carbon of any kind in your cylinder becomes a hot spot causing a burn before ignition event . In that situation the preignited fuel causes more carbon to build and rocks the piston in the bore due to an uneven flame umbrella, its why we have spark screens, preignited carbon becomes super heated and breaks off in the preignited event.
I add octane boost to all my small engine gas or use the highest available because once you add mix oil to that gas you change the octane rating. Starting with 87 and adding a 32:1 or 40:1 organic based oil is gonna drop it to 76-70 octane which is right in line with Mccullochs recommended octane rating. Personally I'm concerned about the carbon hotspots ,so I use synthetic mix oil and a higher octane for complete uniformity of burn.
I would NOT recommend lead for a non valve engine, or using AV gas because it has a deicng agent in it that can mess with burn uniformity at normal temperatures.
This is all just personal preference for me though ,heck I'm sure there's plenty of old saws that were run using the cheapest gas and 30wt oil for years.

More good info. Thank you

 

[mogulmasher]

I think one reason for some manufacturers recommending the use of higher octane is to protect against engine damage. Fuel loses octane as it sits. Let's be honest average home owner is buying whatever for fuel and probably letting it sit on the shelf for longer than they should. If they buy 91 or 93 odds are it'll still be at least 87 octane 4 months later when they use the fuel up.

 

[Max the Mac Man]

Well the 10-10s has me stumped. At this point I think the carb is bad. I rebuilt it. Even changed out the Welch plugs. Held vacuum good. Put it on saw it popped once then flooded. Gas coming out exhaust now. Gas in carb box again.Pulled plug cleared it. Flooded again. That was last night. Pulled carb this am checked needle value assembly and Welch plugs. Put it back together. Got it to crank and never got a screw driver on it before it it died. Flooded and gas everywhere. Going to pull another carb off a parts saw and rebuild it. It’s a test of wills now. I am gonna figure this out lol

 

[mogulmasher]

Is the needle lever set level with carb body? Did you put the tit on diaphragm into slot in lever? If you don't it can push down on lever and hold needle open.

I know these are kinda obvious things but good things to double check.