The Cessna 120-140 Association Forum

What do you use to connect the mixture cable end to the mixture arm of a Marvel Carb.?
It has to be a 1/4 inch dia. "B" nut type that can swivel.
Need advice.
Charlie Webb

Charlie, would this (below) work? I'm not sure about the Marvel connection, but it's what is installed on my Stromberg mix arm. ($11.85 @ Spruce).
Mac

Hi Charlie!

The parts manual for the 140 shows the Clamp (bolt) to be part # 0450311 for the Marvel-Schebler carb.

I'm editing this because the McFarlane eligibility list shows the Cessna part # 0450311 as being replaced with MCS2323-1, which is a 3/8 bolt (AN-3 size). So looking at the list for the right bolt won't work. You can use the Product Details chart to find the 1/4" bolt that corresponds to that you need.

In addition to Mac's suggestion...

These sites will get you started. You'll have to determine which one applies to your situation.

https://www.mcfarlaneaviation.com/produ ... MCS2323-2/



https://www.aircraftspruce.com/catalog/ ... pbolts.php

Not quite so specific information but FAA/PMA for 120-140.

(Went down this rabbit hole a few weeks ago getting ready to hook up a new mixture control in an O-200 conversion.)

Hope this helps. Someone else may have more specific information.

Steve A H

The original is an AN bolt with a hole drilled in it.

Huey,

I've never seen an original "clamp" bolt, and what you say makes sense. The location of the hole probably resulted in the part number 0450311.

The McFlarlane bolts (clamps) (AS&S sells their clamps too) are stainless and have a radius on the edges of the hole.

I must admit, I'm having a hard time paying $17.80 (McFarlane)or $23.50 (AS&S) for a bolt with a hole drilled it, even if it is stainless! I haven't hooked up the mixture yet, but will probably get the right AN bolt, drill it and put it on! I'll try to use a countersink to soften the sharp edge of the hole.

Steve A H

I had the "drilled bolt" set up on my mixture control. It eventually failed due to frequent flexing and eventual metal fatigue. Switched it to a "B" nut.

Maybe it's oldtimer's disease, but a "B" nut is for a flared hydraulic line, isn't it?

lol, for the mixture cable wire its a an bolt drilled above the threads preferably with a block such as this that's not metric:

https://www.ebay.com/itm/Safety-Wire-Dr ... SwltNefxEZ

This attachment works good as long as the bolt pivots on carb arm and the wire isn't over torqued with nut ( metal self locking style not fiberlock), it will break in short order if the hole is drilled wrong and bolt is tight.

The throttle arm hookup is usually an an rod end type or the old ball and socket style ( which I would throw away).

Don't cheap out here as you will loose engine power if something breaks,

Aircraft Spruce sells Cable End B Nuts, they also sell B nuts for hydraulic lines. Confusing maybe? If you go to their web page and search B nuts, the first picture will be of the cable end B nut, then a hydraulic fitting B nut, then a drilled bolt with a nut and washers for 71 cents. How did they come to be called B nuts?

On a loosely related note, Spruce used to sell a SS cable "grip" fitting with integral fork/clevis that attached and functioned perfectly on the carb heat cable end. The only problem...the "harmonics" would snap the cable just above where it gripped the cable. On the way to the Gainesville convention and over a large, steamy lake in Ark I was aware of (and, "sensing") perfect carb ice conditions, but confident that all I needed was to "pull heat". When I did, and when the cable came all the way out, my confidence drained! ...worked out OK, but a good little reminder that adding nifty "unapproved after market" stuff may not always be a great idea, no matter how tempting. Mac