Rebushing a solex 34pict3

First of all, make sure your carb is a genuine Solex. It should say Solex, Deutsche Vergaser co, Made In Germany on it, or something along those lines. If it says anything else (BACAR, Käfer, Brosol, or any country of origin that's not Germany, or no country of origin at all) throw it in the trash and look for a genuine one.

You have to extract the old bushes, which is reasonably hard if they are bronze. You can try to press or tap them out, one method is to tap a thread in the bush, and then use a long bolt or something, but supporting the carb body during this is always problematic. If you heat the carb body, it helps.

Once you have the bushes out, just measure the resulting bores (as the bronze bushes will no doubt shave some alloy off the sides as they come out, so the diameters could vary), and make a bronze bush to fit in the bore, with a hole in the center roughly the size of the spindle (slightly less). Make the bushes o/d a little bit bigger then the bores, for an interference fit, but only slightly, since those alloy carb castings are really really weak. Do each side separately, don't just measure one side and make two bushes.

Now press the bushes into the casing.

Once they are in, make sure your throttle spindle is not oval, and get an adjustable reamer and ream the insides of the bushes (together, at the same time, using the same reamer through both, to keep it parallel). Take small cuts until you can fit the spindle in using moderate hand-pressure, and you can turn the spindle once it's in position with two fingers, without too much effort. If it has a little preload, its not a problem, as long as you can comfortably turn it with two fingers, stop there. Since on the beetle engine the throttle return spring is quiet powerful, a little too tight is better then a little too loose (since if it's too loose you have to start again).

That's it.

That's how I do it anyway. I gave up doing it with set measurements ages ago, because there are variations in carbs. I just do each one bespoke, like I described.

hugging corners said:

hello. im new here, but very valuble info!
have 1 Q?

why not just redrill the both opening oversize (eliminate dimple) to standarized bushes size, press in and them ream inside, rather to measure bushes on each side and try to fit it by outside diameter

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Because bronze bushes are cheap and available and easy to machine, whereas carb castings are precious, hard to find, impossible to make economically, rare, and very fragile.

The bits that hold the bushes are very thin and weak castings, even pressing in bushes which are made to spec can sometimes crack them. I tend to use like, literally almost no interference, or at least tiny amounts, and use thread-lock type stuff. As long as its gas tight and the bush does not just fall out, and the friction of the spindle won't make the bush spin in it's housing, it's good enough. If you are used to rebushing other carbs, these Solex carbs can be a total pain in the ass.

I did a few ball-bearing and O-ring seal conversions for carbs and used on forced induction, and although it was successful, the amount of man-hours it took to do it effectively with the piss-thin castings kind of outweighed the advantages.

I try to NEVER do ANYTHING to the carb castings. They are fragile and I am constantly paranoid about breaking them. Make any components to fit the carb, not the other way around.

The only exception is sometimes I shave off a few 0.001mm to return the flanges to a true parallel fit. I used to have a tiny mill (for making model aircraft engines I think) that was great for that, but unfortunately someone accidentally ran over it and totally shattered it's frame, which sucks. I need to buy a real one really.

Stuff (like lathes and mills and tooling) that's designed for model engineering is perfect for working with carbs.

There are other methods of doing this, but this works for me.