Unusual Marvel top casting

[Jerry Kzoo]

I have read through the excellent Marvel Carb dissection thread and as a result I was going to refurb some of these carbs that I had laying around. I have disassembled and cleaned up 3 of them and on one of the top castings there is no hole going through the passage where the idle fuel adjust screw passes into the venturi area. In the dissection thread it is identified as:

The bright dot (7) at the center is the tip of the idle adjusting needle; this is the primary idle orifice.

Do any of you know if this is just a machining error or if some of the carbs were made this way?

Thanks, Jerry

[Gary WA]

Originally Posted by Jerry Kzoo

I have read through the excellent Marvel Carb dissection thread and as a result I was going to refurb some of these carbs that I had laying around. I have disassembled and cleaned up 3 of them and on one of the top castings there is no hole going through the passage where the idle fuel adjust screw passes into the venturi area. In the dissection thread it is identified as:

The bright dot (7) at the center is the tip of the idle adjusting needle; this is the primary idle orifice.

Do any of you know if this is just a machining error or if some of the carbs were made this way?

Thanks, Jerry

photo?

[duke36]

I believe #7 is the fuel bowl vent in the dissection from prior thread. If referring to this diagram, the brass idle mixture screw should go directly in to the venturi. (#7).

[Jerry Kzoo]

Ok, I think I have pictures showing the top casting. The one looking down the venturi shows only one hole where there should be 2 I think. The other pic shows the idle mixture screw bottoming out on the casting where the machined hole stops short of reaching the venturi.

I cannot see how this carb would ever idle correctly, but I am willing to learn from all of you out there.

Jerry

[Gary WA]

There is a little info in the Sep/Oct 95 Restorer pg12

[abachman3]

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I do not have an answer, only that I have seen that hole missing on several of the Marvels that I have.

[Jerry Kzoo]

abachman
I am wondering what the idle mix screw looks like for the ones you have that are missing this hole. Could you post a pic?

Also, have you run any of these carbs with this missing hole. I am wondering how they idle.

Thanks, Jerry

[abachman3]

I presently have in excess of 25 Marvel carbs. Most of them have never been freshened. I only have one that I run on my car and it does have the hole. Sorry that I cannot be of more help.