Some retrofits for Mac Flat Back Carb

[chy_farm]

It sometimes rises up on the talks of guys who love old McCulloch saws that the most annoyance about her carburetor is its primary pump. Not a few enthusiasts of old McCulloch seem to have the same sort of experience that they were not able to start their saws with this pump, which incident often leads them to a lot of endless job to thinker the pump, looking for some explicit evidences for the failure.

After heck of a job of this kind, I made up my mind to remake or fabricate a new for her carb, with a plastic made easy and cheap standard primary pump which we can get on the net.



Chy

 

[jake wells]

@T.Roller

 

[T.Roller]

@T.Roller

I fixed mine, I put a HL on it lol

 

[jake wells]

I fixed mine, I put a HL on it lol

a who?

 

[chy_farm]

I fixed mine, I put a HL on it lol

Good morning Dave, it's a nice alternative too. I wanted to put SDC with a joint manifold like the one we see on a Super 795, but SDC does not need primer, lol.

(correction)
Super 795 ==> Super 797

 

[T.Roller]

a who?

Tillotson hl

 

[T.Roller]

Good morning Dave, it's a nice alternative too. I wanted to put SDC with a joint manifold like the one we see on a Super 795, but SDC does not need primer, lol.

I had a flat back on my super 250 when I got it. Never ran right and I just so happened to have a 250 parts saw with a good HL on it.

 

[chy_farm]

The joint part is this ;

 

[T.Roller]

Good morning Dave, it's a nice alternative too. I wanted to put SDC with a joint manifold like the one we see on a Super 795, but SDC does not need primer, lol.

Good morning to you sir, it's 11:10 pm here

 

[T.Roller]

The join part is this ;

View attachment 77561

I like it!

 

[chy_farm]

Long hose for squirting fuel, short for sucking.

 

[chy_farm]

Good morning to you sir, it's 11:10 pm here

Lol.

I like it!

Thanks, glad you like this small contraption, lol.

 

[chy_farm]

Replaced the right button with a newly made lid, on which a plastic pump comes to sit in.



At its back a short brass tube is engaged to the top end with bent edges of this lid plate.

Side view ;


Drill four small holes and give it a finish with file, engage this pump into the place ;


Chy

 

[chy_farm]

This shows another type of the joint, not using a short brass pipe. Metal epoxy is used for the pad in the center to hold the pump unit. ;


Make the center part hollowed to accept the pump. ;


Done. ;

 

[smokey7]

So this gets the fuel to the carb to cure the starting issues? I got a similar carb here on a clinton 250.

 

[chy_farm]

So this gets the fuel to the carb to cure the starting issues? I got a similar carb here on a clinton 250.

Yep it works pretty well on my old 740,this unit is installed on her;

hope this could encourage you go further on your old girl.
Chy