McCulloch Carburetors

[hexen71]

yep mine is the electric start

 

[belgian]

It is late and I might not being seeing the obvious answer in the photos. What I was asking about is whether or not you could use the old OEM gasket with the slots in it and the new AM pump diaphragm from Bob's kit in order to get the full up down motion restored to the fuel pump.

First want to say that Mark did a real nice job detailing this carb work. Very helpfull and I'm looking forward to the "Bullfrog carb review" in the future.

I would assume that when the carb pump is working fine during operation, I see no particular reason that the gasket assembly would not be working properly during the primer operation. Hence, If the primer is not working, I'd check probably if the primer assy is working OK, especially the vacuum function (O-rings) and the fuel passages. Is there a possibility that the AM set is blocking a fuel passage ? Just a wild guess, of course but something maybe worth checking.

 

[lawnmowertech37]

I have not been able to locate the OEM fuel pump kit, only the parts I have received from Bob. B200 told me he got some from Bob and they were the OEM style. Bob has lots of stuff and his inventory changes a lot so you get what he has when you order.

Mark

mark what is the part # for the fuel pump kit ?

 

[GASoline71]

Mark... fantastic thread mang!

I have a Flatback that came out of my 640 that is just sittin' on the work bench. It is is great shape, but needs a rebuild...

Thanks for the detailed pics and info!

Gary

 

[Justsaws]

First want to say that Mark did a real nice job detailing this carb work. Very helpfull and I'm looking forward to the "Bullfrog carb review" in the future.

I would assume that when the carb pump is working fine during operation, I see no particular reason that the gasket assembly would not be working properly during the primer operation. Hence, If the primer is not working, I'd check probably if the primer assy is working OK, especially the vacuum function (O-rings) and the fuel passages. Is there a possibility that the AM set is blocking a fuel passage ? Just a wild guess, of course but something maybe worth checking.

I do not know for sure but the space created by the cut gasket between the body and the pump diaphragm might allow the primer to pull and push the fuel through the carb. By removing the cut gasket and placing the diaphragm flush against the body the primer may not be able to move the diaphragm through the full range of motion and render the primer in effective.

 

[sawbones]

Great job Mark

One of these days I will need to tinker with some flatbacks I have on a few runners.

Now you need to link this thread into your signature..

Here is an ad I found yesterday,

It is from 1975.

 

[heimannm]

Calvin, the OEM metering diaphragm/gasket is 55067 and the fuel pump diaphragm/gasket is 57274. The seat for the primer is 59480.

The little duck bill for the 10 Series carburetor is 63041.

Sawbones, thanks, I still enjoy teaching I guess. It never occurred to me that the McCulloch carburetors were made for them by Walbro, even though I have seen the McCulloch branded SDC carburetors. Very neat information. I added a link to this thread to my signature, but I had to get rid of some saws to do it.

Justsaws, now I understand your point. Problem is most of the time the old gaskets are shot and can't be reused. If I were a lot more patient and had fine motor skills I suppose it would be possible to cut new ones but for now I don't think it's possible for me.

Roland, I will have to look things over again this week and see if I can learn anything further about how it's supposed to work and what is going wrong.

Always something more to think about and try in any case.

Mark

 

[lawnmowertech37]

Calvin, the OEM metering diaphragm/gasket is 55067 and the fuel pump diaphragm/gasket is 57274. The seat for the primer is 59480.

The little duck bill for the 10 Series carburetor is 63041.

Sawbones, thanks, I still enjoy teaching I guess. It never occurred to me that the McCulloch carburetors were made for them by Walbro, even though I have seen the McCulloch branded SDC carburetors. Very neat information. I added a link to this thread to my signature, but I had to get rid of some saws to do it.

Justsaws, now I understand your point. Problem is most of the time the old gaskets are shot and can't be reused. If I were a lot more patient and had fine motor skills I suppose it would be possible to cut new ones but for now I don't think it's possible for me.

Roland, I will have to look things over again this week and see if I can learn anything further about how it's supposed to work and what is going wrong.

Always something more to think about and try in any case.

Mark

thanks mark

 

[brokenbudget]

Is your 5-10E an electric start? Cool beans, I have a 3-10E and a 5-10. The 3-10 has a Walbro SDC carburetor, the 5-10 had the McCulloch flat back/bullfrog but someone beofre me converted it to a Tillotson HS I believe. Mark

mark, it's my understanding that they came with both. the flat backs were on the earlier models (within the first year or 2).
when i first came here i was going to fix up a 10-10E (sure did look like it said 1-10E). it had the flat style carb on it, but both my "newer" 10-10E
and 5-10E have the walbro on them.
it was also my understanding they kept the flatty around for the bigger saws as they flowed much better.

oh yeah, my 5-10E's electric start works very well. just finished another battery pack for the 10-10E but there is still something wrong either with the switch or in around the windings. i have to 'help' the saw to start turing over. once you get the first spin it will turn the saw over (decomp working fine) it seem that the motor is a little low on power. could be one of the rectifiers in the switch or a weak winding.

 

[cpr]

Oh, does anyone know where I can get about 6 of the metering needles for the McCulloch carburetors as well as a few extra primer seats? After all this I still have a few leakers and it appears to be coming out of the carburertor throat while the saw is setting not running.

Thanks!

Mark

Just a thought, but I had the same problem with my Tilly HL on my 795. I checked everything and the answer was the brass nozzle for the metering valve was over torqued. I reset it minus torque wrench, but it was just barely seated, no pressure on it whatsoever. Leak gone. BTW, no I have not had time to figure out what the "noise" was on it. Maybe this week.

Great thread and very inspiring!!!

 

[lawnmowertech37]

mark i found something that may interest folks is a mcculloch carburetors manuel and repair book with parts lists diagrams of all the mac carbs in it it was in a mcculloch book i got from someone

also has repair manuels for basically all the mac models

not to mention parts lists

that book is about 7 inchs diameter

 

[heimannm]

I had a chance this week to meet Joe Salva from Sugar Creek Supply. This company produces carburetor kits as well as decals, etc. for a lot of saws that are NLA anywhere else.

Prices are quite reasonable as well.

I picked up a few kits for the McCulloch/Walbro flat back carburetors off the big saws, as well as one for the Carter ND on my Wright GS5020A.

You can find more details over at cscc.se

Mark

 

[lawnmowertech37]

I had a chance this week to meet Joe Salva from Sugar Creek Supply. This company produces carburetor kits as well as decals, etc. for a lot of saws that are NLA anywhere else.

Prices are quite reasonable as well.

I picked up a few kits for the McCulloch/Walbro flat back carburetors off the big saws, as well as one for the Carter ND on my Wright GS5020A.

You can find more details over at cscc.se

Mark

Yea Joe is gifted in that area

 

[heimannm]

I put one of Joe's (Sugar Creek Supply) kits in a McCulloch 440 a few weeks ago, saw did not seem to run right but I thought maybe it was seals, etc.

I found out this weekend that the plug wire was broken, spark was intemittent, replace the coil and the saw now runs very well.

Thanks to Joe, reasonably priced kits for the McCulloch/Walbro Mac carburetors are readily available.

Mark

 

[hep1023]

This should be a sticky.

where can i find a metering diafragm and oil pump diafragm for mac '(à ?


number on carb is 61853A

 

[kev1n]

small mcculloch flatback

hey guys, i'm having some troubles with a 1-76. i rebuilt the carb and the saw runs great but when i shut it off it just keeps spitting gas out the carb until all the gas in the carb and fuel line is drained. also the pump isn't working that good. any clues as to what to look at first when i tear this apart again. thanks kev1n

 

[heimannm]

hep - if your carburetor looks like the McCulloch carburetors in this thread, you can get the kits from Joe Salva at Sugar Creek Supply, you can also find a link to Joe over as Chainsaw Collectors.se

kev1n - 1st thing I'd do is check the height of the metering lever, should be flush with the body of the carburetor as shown in this thread, or the needle itself might be bad, as I mentioned they are available from Bob Johnson, or from just about any older Walbro carburetor.

You should also make sure the fuel line is tight, and that is isn't leaking where the hose passes through the fuel tank. I don't remember if the connection on the 1-76 is a fitting through the tank or a hose with a molded grommet, I had good luck wrapping teflon tape around the grommet on one saw as described in this thread.

It could also be the primer, they are rather notorious for leaking and are relatively expensive to replace (I think I paid $25 for the last one I got from Bob). On the other hand, with the primer in good condition starting the saw is a real pleasure.

Mark

 

[kev1n]

thanks for the reply, it has the fitting between the tank. the gas is coming out of the hole in the center of the carb near the front. just keeps pouring out. does the sugar creek supply kit come with a new needle and seat?

 

[heimannm]

None of the suppliers I have found include the needle with the diaphragms and gaskets.

You can get a needle and lever from Bob, probably others as well as it is the same needle as used in the SDC carburetors on the 10 Series McCulloch saws. The levers are different between the SDC and the MAC carburetors, so the needle kit comes with both.

Mark

 

[kev1n]

i've read your thread a few times. there is some great info there. thanks for putting it all together. i will try the method you did without the fuel pump gasket if everything else looks good.