McCulloch Carburetors

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Mac CARBS

Great info to use for my saws. Thanks everyone for putting your wisdom and humor into this.
Will:msp_biggrin:

 

[mcc 86]

great info

Hey Mark. just wanted to let you know, and everyone else who has contributed to this thread a great thank you! This is just the kind of info i love to see. (very informative and attention to detail) I could defantly use this info. Thanks again!

Aaron

 

[jerrycmorrow]

great thread youse guys. subscribing and bumping

 

[Frank Boyer]

I have a 1-86 carb that I need to work on. The primer doesn't work.

 

[heimannm]

Other than replacing the external O-rings between the primer and the carburetor body, there is not much that can be done with the primers.

Start searching e-bay or any other parts suppliers you may know of to see if you can locate a new one. There are a few out there still. I have seen them go anywhere from $5 to more than $15 on e-bay.

Mark

 

[Frank Boyer]

Thanks

 

[Eccentric]

The last two NOS primers that I saw on feebay (from the same seller) went for $25 and $50. Frank I may have a good used one for you. I take it the NOS HL103 thing didn't pan out. If that deal does come through I'd still be down for at least one.:cheer:

 

[Frank Boyer]

He only had one and it was $60 plus shipping.

 

[FergusonTO35]

On the subject of Mac carbs but way smaller, I just rebuilt the Zama M7 on my Mac 160S. Anyone know the suggested initial settings for it? It starts and runs but I'm having a heckuva time getting it to idle without the chain moving.

 

[heimannm]

In general I start with the low 1-1/4 to 1-1/2 turns and the high 1 to 1-1/4 turns open from lightly seated.

If the idle speed is correct and the chain is still moving it could be a failing bearing in the sprocket/drum, or that the clutch springs are just weak and worn out.

Mark

 

[FergusonTO35]

Thanks. I ran it some more after work and it looks like the clutch is the problem. It starts, idles, and cuts great. You can turn the idle up and down no problem, you just can't run it slow enough to keep the chain still. I know everyone hates these things but when its running well this little Mac is one of my favorites. At one point I had six of them, I think I could take one apart and put it back together in a coma.

 

[burl1984]

I have a 1/72 BDC 14 mounted to a high rise manifold which is supposed to fuel a SP125C/101b modified saw. I think I have rebuilt it completely but can't get it to fire up. I replaced all the parts the way the old ones came out but now I'm thinking the original carbutetor build may have been incorrect. Can somone post a link to a pictoral sequence for rebuilding a BDC14 please? I can get the saw to pop and run for a short while by putting some fuel down the bore of the carburetor but it doesnt seem to want to pick up fuel. I pulled the clear fuel line off and pulled the starter cord over several time and it seemed as iff the fuel pumped back out the fuel inlet fitting on the carburetor instead of sort of into the fitting. Could it be that the pupming mechanism is reversed inside? I'm relativly new to the McCullochs and have basically been builing this saw from lurking on the Karting forums and this site. The tank is a custom aluminum tube mounted infront of the BDC14 like most of the youtube videos show of the modified 101b saws.

Any help would be greatly appreciated.

Thanks,

Burl

 

[heimannm]

I have an IPL for the BDC14, send a "conversation" with your e-mail address and I can forward a copy. Those carburetors have a duck bill valve and some additional circuit plate diaphragms and gaskets, plus a different metering diaphragm than the standard flat back carburetor (66092 vs 55067 used on the saw carburetors).

Mark

 

[burl1984]

I have an IPL for the BDC14, send a "conversation" with your e-mail address and I can forward a copy. Those carburetors have a duck bill valve and some additional circuit plate diaphragms and gaskets, plus a different metering diaphragm than the standard flat back carburetor (66092 vs 55067 used on the saw carburetors).

Mark

I purchased all new circuit plate gaskets 1 thicker and 1 thinner and the circuit plate diaphram really thin. The Duckbill was also replaced at the same time. I purchased the kit BDC14/16 from marmax's karts and parts ca. I actually bought 2 kits because in the long process I have been taking to build a saw for the local competitions I have accumulated almost enough parts to build two saws. If i happened to ruin any of the soft parts a can just harvest them out of the other kit.

I'll pm you with a personal email.

Thanks Mark!

Burl

 

[heimannm]

I have tried to add back all of the missing photos, hope this helps some of you with the MAC carburetors.

Mark

 

[SEAM]

I have a number of these flatback carb Macs with dead primers... I use a sheet of copy paper covering the carb bore as a choke to start them. Works perfectly.

 

[heimannm]

Creative solutions abound!

Mark

 

[burl1984]

I have tried to add back all of the missing photos, hope this helps some of you with the MAC carburetors.

Mark

Mark,
Thanks for the IPL. I checked my rebuild job on the bdc14 carb. The only difference that I could tell between the IPL and my build was the rotation of the duckbill valve. The one that was in the carburetor originally was basically goo. I put a new one in but was about 90 degrees out from what the IPL shows. I'll report on conditions soon.

Thanks,

Burl

 

[burl1984]

I got everything re-assembled and didn't have to dump raw fuel down the carburetor to get it to pop. I saw somewhere while lurking that 1 turn out on the Low and 1.5 turns out on the High would be a starting point for the carburetor needle settings. I did a little adjusting on the low to add some more fuel because it kept dying. But at least for now i'm better off than before. Just in case anyone is wondering the carburetor I'm using is not the chainsaw model flat back, it is the MC 91-93 kart engine petrol carburetor w/o the pop off settings or the high idle setting. I did purchase an oem choke plate, arm, spring and detent ball to make it easier for starting.

 

[burl1984]

I tore down the saw and realized that I had in fact already installed the lower compression model head per Terry Ives advice. I did notice though while I was loosening the head bolts that they seemed rather easy to loosen. Does anyone use loctite on the 101b head bolts? I re-torqued them and set the lever height on the nos carburetor at the height of the housing. I'll report back this afternoon.