MTFCA Forum

I purchased three U & J carbs last year as a lot, from one of our Forum posters (thank you). One of them had been all but destroyed. The main jet was bored out and extended "up" into the venturi like a submarine periscope; the venturi was removed completely and replaced by a cobbled up hunk of aluminum.

The void where the main jet was crudely drilled out has been filled in and machined back to as-new, a new venturi is done and now an interesting, fairly delicate venturi spacer needs to be made. This spacer clamps the venturi in place, as the throttle body is screwed to the main body of the carb. As finished, the brass is only .025 thick. Pictures of that job follow:

First, brass tubing is cut to rough length and turned to size...then a sheet of brass is rough cut to an oversize diameter. Four very tiny bits of silver solder are placed inside and heated. The fillet is absolutely minimal and wicks to the outside to give a nice undisturbed fillet on the outside, too.



Next, the flat sheet of brass is brought to diameter and bored to the ID diameter of the U & J's throttle body


Then finally, everything is cleaned up and now the solder seam on the OD disappears as the part is given its final finish. Once installed, the part is functional and virtually indistinguishable from an original


If you're curious, that part took 5 1/2 hours make. Material cost of raw material - brass tubing and brass sheet was $45 before shipping. Boring from solid brass would have been a horrendous waste of material.

I probably could have spun this part like the original, but I don't think it would have been any faster.

To me, a "repair" is something that will make the carb work, and perhaps a bored out slug of aluminum made in 15 minutes would have worked. On the other hand, to my mind, a "restoration" puts the carb back to original - indistinguishable from as-new.

I prefer to restore.

This kind of work is neither quick nor cheap.

Beautiful work Scott. I can imagine that holding that part in order to cut the ID in the bottom plate was tricky.

Where's that "like" button when I need it?

Howdy, Scott. I hope all is well with y'all. Your work on this part is beautiful, as always.

Just a word about your reference to the horrendous waste of material. As you know I worked in a machine shop for many years. Maybe I'd be machining a big shaft for a gearbox and the lathe pan would be holding several bushels of chips. Guys would stop by and comment that my job sure created a lot of waste. I'd tell 'em we purchased this big old chunk of bar stock which wasn't good for much of anything but hidden inside of it was this beautiful shaft. That pile of chips is nothing but the peeling. There's no waste at all. Besides, that stuff gets recycled.

My best regards, have a good day. Bob

Some time back, I had a Zenith in for restoration which was missing the fuel inlet elbow and bolt. The first thing to do was to find a suitable example and duplicate it.

Parts are blanked out and then are soldered using silver solder. The amount of solder consists of two very tiny chips of solder, placed 180 degrees apart.

The pictures pretty much tell the story:


Because the original part was a casting, and the new part was a fabrication, when trying to duplicate a part as faithfully as possible, there are some considerations to be made. Where the casting has a filleted transition from the body to the threads, the fabrication has a much smaller fillet. Fillet size and final color of the solder can be controlled somewhat by using one silver solder over another, and varying the amount used. Because as the part ages, the solder will become more visible due to color change, I opted for a bit of a compromise, erring more toward a less-visible joint at the expense of a smaller fillet:

to be continued...

Continuing with the fabrication, more machining is involved:


And now some clean up to bring back the correct finish:


After about 8-9 hours of work - Finally, an original and the reproduction compared:

Scott,,

Do you silver solder with a torch, or in an oven/furnace?

usually MAPP gas

I don't have a nice torch anymore and am contemplating treating myself to one again. I could do with some more heat with less dwell time.

Exceptional work as always Scott!

Very impressive.

Gentlemen, thank you for the thoughtful comments

I had always thought it would be nice to find someone who wanted to learn this sort of stuff from me, as I did as a young man, but no one has ever asked. I've worked alone long enough now that having anyone other than my wife around would drive me to distraction, so the pictures are the best I can do. If they pique someone's curiosity to learn more or provide some inspiration to someone down the line, that would be great.

Scott As My mother says "It's too bad we can't hold the Young'ns down stick a funnel in their ear and pour in all the knowledge they'll ever need!"