I've went through everything on them and I can't find anything that doesn't seem right. No brass gov on either, that was only one specific carb of the HDBs. Meter lever height is perfect according to walbro tool. Needle ends look fine. Its super clean. Replaced the little diaphragm check valve with new oem walbro, also oem walbro kit. Checked welch plug & changed, was fine underneath, no crud. I guess it would make sense that perhaps the needle & seat might simply be worn, I don't know. I don't really get how these old saws run while spitting fuel out. I had a little craftsman 2.0 and a little homelite xl or something that did that too. So that's 4 total I've seen now that ran and spit gas while doing it. This mac 610 runs the best out of all of them that did that. The remington 2nd best. They are also the largest. The little homelite was just pouring out of there and it didn't run very good but it did. I don't know exactly how they do it. I should have bought the good runner w/ a 24" bar I could have a few weeks ago and then I could use that one to have my answers. Guess I'll keep looking and waiting for another one because I can't really do anything more with what I've got here unless I buy a brand new carb for 45 or so from bob. I'd rather grab a whole running saw that doesn't smoke to fart around with though and swap parts around to really get a good idea of whats doin what even if I don't know exactly why.
McCulloch Pro Mac 610 - Runs great but smokes like madness & fuel everywhere
- Thread starter B.C.
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SteveSr
Addicted to ArboristSite
If you replaced the welch plug(s) then you likely have a leak which will allow fuel directly from the metering chamber to the idle/mid-range passages. The only way you'll find out is to pressurize the venturi of the carb and look for bubbles with soapy water. The attached will give you some history and instruction.
I have never had any luck successfully resealing a replaced welch plug. Regular filled epoxy will probably work long enough to tell if this is your issue. Zama and Walbro both stopped using sealant for a while but even they had leaks using their special tooling. Zama has since gone back to using some sort of filled red sealant while Walbro is using a very small amount of some light green/blue clear sealant.
I have never had any luck successfully resealing a replaced welch plug. Regular filled epoxy will probably work long enough to tell if this is your issue. Zama and Walbro both stopped using sealant for a while but even they had leaks using their special tooling. Zama has since gone back to using some sort of filled red sealant while Walbro is using a very small amount of some light green/blue clear sealant.
I suppose that is possible, but I've had the carb on and off about fifteen times, heh. The welch plug was done somewhere toward the latter there. It did the same before and it did the same after. I guess if you are saying it leaked before and now it still does perhaps. Suppose I could try sealing the welch plug with something, maybe some motoseal. I'm guessing just super glue would probably work fine just for a test. Or some seal all which is gas resist. Seemed like it was in there damn good, and I punched the new one in real good too. Never heard anyone else mention that they leak a lot and always will if you replace them for all I see them mentioned.
SteveSr
Addicted to ArboristSite
Unfortunately you won't know if the welch plug leaks until you either test the carb or seal the plug with something else. And, yes, the original could have also been leaking if ethanol gas had dissolved the original sealant.
I would definitely NOT use Motoseal as it never completely sets up. I would try something like JB Weld marine weld epoxy which should be pretty gas and oil resistant.
After just looking at both a new Zama and Walbro carbs I am beginning to think that they are now using some form of cyanoacrylate adhesive. Zama is using a filled product while Walbro is using a water thin unfilled product. I also took a brief look at gasoline and alcohol resistance (see attached) and cyanoacrylates seem to have very good resistance to both gasoline and alcohol. Based on this you might want to clean the area around the plug and try some superglue (the water thin stuff not the gel) This way it will seep into any voids between the plug and the casting.
backhoelover
Free service manuals and service tool info
There is ways to test Welch plugs with mity vac ill send it when I get home from work
SteveSr
Addicted to ArboristSite
Thanks, but I think I already posted this for him...
If the saw is so rich it's spitting gas out of the carb, it won't run good at all! B.C. I really believe you are chasing the wrong problem here. Your carbs are probably fine! I am betting what you are seeing come out of the muffle is nothing more than diluted bar oil from the earlier repairs. You likely have an oil build-up in the crank case and a big puddle inside the muffler can. I would suggest you fire up that saw, fine tune the carb until it runs correct......and cut some wood with it like you stole it. Get it up to running temperature and don't give it a rest until that smoke clears up. You will be running a smoke fogger for quite a while until it burns off all that residual oil from the case and muffler can. Just my 2 cents!
backhoelover
Free service manuals and service tool info
Just noticed that lol. I got the complete set of tech training if you would like them. Also got the gold and platinum ones too
SteveSr
Addicted to ArboristSite
Sure! I am a well trained archivist! Do you have a private share where you can post and then PM me a link?
I think a lot of guys use Clear fingernail polish for the Welch plugs and some of the gaskets in the carb kits are thinner than the original which throws off how your metering lever set
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Sent from my SM-G920V using Tapatalk
Well, quick update. I have gotten 3 of these running now, and they all smoke quite a bit really. The original one still smokes the most and actually spits a little fuel. The other two smoke to the point the muffler does get a bit wet as does that side of the cylinder & the half round deflector on top, but not as bad as the original. I can swap the 5 carburetors around I have and they all run the same. So the one that smokes the most must have worn rings or something, it still cuts just fine though. The best one of the 3 cuts like a monster, most powerful saw I've owned so far. (Its the newest, and eager beaver 3.7 made in I think the 90s as opposed to the other two being early 70s.) The 3rd one isn't 100% and I'm thinking it's probably seals considering age. After all this I've concluded I have no idea how anyone has one of these that doesn't smoke more than pretty much any other saw. It also somehow was WAY more power than the Husky 55 and Echo 500VL I have even though it's only 10cc bigger, it feels 2x as powerful and I can really use the spike to tear through a log. (That being only the Eager Beaver that actually runs good and has excellent compression but is still quite smoky, easily 2 or 3 times more smoke than the 500VL and the Husky hardly smokes at all.)
**For some reason some of the posts didn't come up before I posted this, now I see them. Yes I would like those manuals please backhoelover.
Rd35 - I don't think that is the issue, muffler is clean on all of them and dry. If I run the smokiest one it does throw a lot of fuel into the muffler so it's not really that dry. It seems to use a whole heck of a lot of fuel so I don't think it's a matter of there being oil in the crank or a puddle in the muffler although that could have been possible, I don't think that's the case, it's just using a crazy amount of fuel for some reason. They all seem to but the first one is definitely the worst.
I didn't read all the welch plug info yet, I figured with 5 friggin carbs that all run the same you'd think one of them would make a difference if it was the carburetor, although I suppose it IS possible that the welch leaks on all of them. The eager runs like a champ though and cuts like a champ, but still smokes more than any other saw I have.
Oh, one other thing I did, the eager had a rotted oil line, I put a new oiler line on and then I made a quick paper fiber gasket which is working well. I didn't want to wait to put a sealer on there so I just made a quick gasket. I imagine it probably won't last as long but hoping that I get a good amount of use out of it before I have to replace it and actually put a sealant on there.
**For some reason some of the posts didn't come up before I posted this, now I see them. Yes I would like those manuals please backhoelover.
Rd35 - I don't think that is the issue, muffler is clean on all of them and dry. If I run the smokiest one it does throw a lot of fuel into the muffler so it's not really that dry. It seems to use a whole heck of a lot of fuel so I don't think it's a matter of there being oil in the crank or a puddle in the muffler although that could have been possible, I don't think that's the case, it's just using a crazy amount of fuel for some reason. They all seem to but the first one is definitely the worst.
I didn't read all the welch plug info yet, I figured with 5 friggin carbs that all run the same you'd think one of them would make a difference if it was the carburetor, although I suppose it IS possible that the welch leaks on all of them. The eager runs like a champ though and cuts like a champ, but still smokes more than any other saw I have.
Oh, one other thing I did, the eager had a rotted oil line, I put a new oiler line on and then I made a quick paper fiber gasket which is working well. I didn't want to wait to put a sealer on there so I just made a quick gasket. I imagine it probably won't last as long but hoping that I get a good amount of use out of it before I have to replace it and actually put a sealant on there.
Ran the Eager Beaver on an actual job the other day and put it through some big maple for a while. Ran like a champ and didn't smoke much. Oiler was working fine (new one from Bob on that one.) I don't even remember what carb I have on it but I'm pretty sure I recall not doing much to that one, think I only did diaphragms and gaskets, and didn't do the little check valve inside. Ran great through a few full tanks of hard use. Had to fix the chain at one point and turned it upside down for a bit. Refused to start after that, figure it must have flooded somehow. (Had to finish the last few cuts with my Echo 500VL which took much longer.) But anyway it ran good and didn't smoke much so I think that original one it's probably just rings is my best guess and swapping the carbs on them they all seem to run the same individually so it seems like the cylinder/piston itself more than anything else that affects the smoke. Of course I'm sure an oiler issue would potentially do that too but I ruled that out on the worst one by running it with no oil for a while. So I guess my best conclusion is that the rings on the original that still spits gas is the culprit to blame for all the smoke. I'm just glad I at least have one now that runs good and now I really love that saw, it's great & cuts like a champ. Thanks all for your help.
I'm sure at some point I might have a carb with welch leaks or some things like that but I'm not sure if I'll ever be skilled enough to figure that out exactly when encountered.
I'm sure at some point I might have a carb with welch leaks or some things like that but I'm not sure if I'll ever be skilled enough to figure that out exactly when encountered.
I just got mine going and it dose the same thing. Your theory of the rings holds some merit, however on the 610 there is a grove above the exhaust port that acts a a decompression from the factory. The 650 doesn’t have this, it has a conventional decompression. So it’s possible this is the cause. I had one years ago and it smokes as well
For the 600 Series saws, heavy smoking at start up is normally related to the impulse operated automatic oil pump mounted on the top of the oil tank. Replace the gasket and diaphragm, or replace the whole pump and the issue will almost always clear up.
Be aware that there are two different versions of the pump and they use different diaphragms. The older saws with the 10 Series type check valve disc use a diaphragm with a tear drop shaped opening for the manual oiler passage.
The later automatic pumps with the check valve built in have a simple hole for the manual oiler passage.
Mark
Be aware that there are two different versions of the pump and they use different diaphragms. The older saws with the 10 Series type check valve disc use a diaphragm with a tear drop shaped opening for the manual oiler passage.
The later automatic pumps with the check valve built in have a simple hole for the manual oiler passage.
Mark
I actually replaced the oil pump as it was not working automatically I didn’t replace the gasket but I used a tiny bit of sealer on it as the gasket was in good shape. I suppose it possibly it’s still bypassing but the oiler seems to work ok
It was nos pump
The saw had been sitting for quite some time so I wonder if it has some congealed mix oil somewhere or if the muffler has a bunch of un burned oil in it from mixing heavy on the oil. It’s got me curious. I had one years ago that was mint and it did the same thing and the oiler never missed a beat. You got me curious now lol
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