Setting Float Height for 1980 Midnight Special Carbs

[D0wn5h1ft]

Picked up a set of Midnight Special carbs a couple months ago and when I tried getting my '79 running gas was pouring out of the #1 and #2 inlets. I had put in brand new float bowl gaskets so I know that wasn't the problem. I tried adjusting the float height but I'm a bit confused as to where the measurements should be taking from on the MNS carbs with plastic floats. I did a bit of forum searching but I couldn't find anything specifically talking about the '80 MNS.



Am I taking the measurements from the float bowl gasket surface (without the gasket on of course) to the 1 or 2 point in the picture? And I assume this measurement is done with the carbs upside down?

I set them to 25.7mm like it says for plastic floats but it still is spewing gas. I assume the next set would be to replace the float needles and the float needle assembly?

Also, I couldn't really tell because of the amount of gas that was coming out but it appeared as though the carb float bowls were leaking out of where the drain screw is too. Is there a gasket/copper washer that goes on the float bowl drain screw? And if so where can I get a new one?

[natemoen]

You measure to #1. Also the floats for the later model carbs are set to 23mm NOT 25.7mm. Gasket removed and carbs upside down. Also check to make sure that the bowl gaskets do not have any chance of catching the float and making it hang up.

Yes there should be a sealing washer on the bowl drain. Should be able to find one at a local hardware store.

[D0wn5h1ft]

You measure to #1. Also the floats for the later model carbs are set to 23mm NOT 25.7mm. Gasket removed and carbs upside down. Also check to make sure that the bowl gaskets do not have any chance of catching the float and making it hang up.

Yes there should be a sealing washer on the bowl drain. Should be able to find one at a local hardware store.

Does a regular old steel washer work? Or should it be copper or nylon?

[BA80]

Copper or aluminum is what you need.

[DAVINCI]

I was never able to find them locally, so I bought a bag of em from McMaster. If you want, PM me your address and i'll drop 4 in the mail. I sure can't use em anymore.

PS they're 8mm X 11 mm X 2mm thick aluminum

[D0wn5h1ft]

I was never able to find them locally, so I bought a bag of em from McMaster. If you want, PM me your address and i'll drop 4 in the mail. I sure can't use em anymore.

Thanks for the help!

I PM'd you my address. Now let's see if I can stop these carbs for leaking all my dollar bills on the floor.

[DAVINCI]

I see your address, but what about a name? lol

[DGXSER]

did you replace the oring under the float valve seat? Replace the float valve?

BTW, nothing special about the mns carbs other than paint.

[Schming]

Picked up a set of Midnight Special carbs a couple months ago and when I tried getting my '79 running gas was pouring out of the #1 and #2 inlets. I had put in brand new float bowl gaskets so I know that wasn't the problem. I tried adjusting the float height but I'm a bit confused as to where the measurements should be taking from on the MNS carbs with plastic floats. I did a bit of forum searching but I couldn't find anything specifically talking about the '80 MNS.



Am I taking the measurements from the float bowl gasket surface (without the gasket on of course) to the 1 or 2 point in the picture? And I assume this measurement is done with the carbs upside down?

I set them to 25.7mm like it says for plastic floats but it still is spewing gas. I assume the next set would be to replace the float needles and the float needle assembly?

Also, I couldn't really tell because of the amount of gas that was coming out but it appeared as though the carb float bowls were leaking out of where the drain screw is too. Is there a gasket/copper washer that goes on the float bowl drain screw? And if so where can I get a new one?

As Nate stated set your floats at 23mm.
Here's how I set mine:

Cut an old gasket to 23mm



Use as shown to check height



HTH

[donebysunday]

Floats

HEY !

VERY interesting way to do the float height ! I'll give it a try myself.

Thank You ! Done };~)

[IanDMacDonald]

Those plastic floats look much easier to set than the brass ones. Any pros and cons vs. The brass?

[skids]

If you cut that gasket straight you will be setting the floats to the ribs on the mating surface rather than the flat. You could compensate for that and I suppose you did.

[motoman]

If you cut that gasket straight you will be setting the floats to the ribs on the mating surface rather than the flat. You could compensate for that and I suppose you did.

Setting on the sealing rib is altitude compensation for those at 5,000ft elev. and above Sid.

[Schming]

If you cut that gasket straight you will be setting the floats to the ribs on the mating surface rather than the flat. You could compensate for that and I suppose you did.

Correct, and leave a, hair of your favorite color, gap between the float and the gaskit-gauge.

[Nubian]

Genius

As Nate stated set your floats at 23mm.
Here's how I set mine:

Cut an old gasket to 23mm



Use as shown to check height



HTH

This held me up 3 days! The fact that I was measuring from the wrong spot did not help.
FREAKIN' GENIUS!!!!!!!!!!!!!!!!!!!!!!!!!!!!
btw my FSM say's float height should be set at 24.7-26.7mm (0.972-1.051")