Reamers for bushing throttle shaft.

HolyHarp

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I have a Nissan Z16 engine carburetor with a very loose throttle butterfly valve shaft. Unless someone has a better idea, I want to bush the holes. I'm looking at a bushing with a nominal OD of 10.5 mm and an ID of 8 mm. I believe I need 2 reamers for this job. I've never had occasion to use a reamer before and I'm not sure which type to get. I'm thinking of a set of adjustable reamers. I'm not sure how to pilot them.

I wonder if there is a simpler way to do this; does Loctite/Henkle have some product that would solve my problem?
 
If the reamers are of the Critchley type, pilots are available that screw on the end of the reamer and have a closely fitting tapered sleeve that slides on the pilot.
 
The stock for the bushing is not likely to be found as 10.5mm material, but can be machined down to the desired size from larger stock. What is the material? Brass? I do not recommend that you use adjustable reamers for that job, they are too fragile and fussy to use in smaller sizes and will not leave a parallel bore to desired size without much care and some luck, especially for a novice. Measure the shaft accurately along it's length and decide the size that you want for the bushing I. D. You will want it snug on the worn pivot area of the shaft while also large enough to slide over the unworn portion. It might make sense to turn down the entire shaft to the smallest current diameter for a better fit and to make installation of the tighter bushing possible. Some of that depends on the layout of the installation, and we do not even know what model carburetor it is. When you know for sure the reamer size you are looking for, you can try to buy one that size. Report back if you need more help. I have lots of reamers, and so do others here, but you are in Thailand, which makes things much more difficult. The bushing could also be made from solid stock, bored to size on a lathe, and then turned to the desired O.D. If there is room to work, the bushings would be best reamed to size after installation in the carburetor. You want the butterfly valve to fit the venturi closely and without binding, and that requires accurate locating of the throttle shaft.
 
Thanks folks. Looking at ebay offerings it seems that reamers usually come with a 1:50 taper. Is this the type of reamer I need?
 
Geoffrey, is the butterfly shaft worn or is it the holes in the throttle body?
Depending on where the wear is, and access after installing the bushings, I would consider making a single bushing as long as the overall length of the total butterfly, turned to OD to press into the throttle body, and reamed to suit the butterfly shaft. After installing that so as to keep the 2 bushings aligned. Then cut the unnecessary section out of the throttle.

Cheers Phil
 
I must confess that shaft is worn as well as the holes in the throttle bodyI'm not too keen on turning the shaft down because I think it would be hard to center. I could mount it in a collet which is pretty accurate. I can't think of an accurate way to support the other end of the slender shaft.

I believe that drilling/boring the brass bushings undersize and reaming them afterwards using the shank of the reamer as a pilot (if possible), might make the holes aligned.

Thanks, Geoffrey
 
there may be commercially available reamers for your application. i have one for quadrajets so there may be others available.
 
Is this enough wear to cause a vacuum leak that will effect engine performance? If you want to do something about it no matter. I would just lathe out to size (ID & OD) the brass bushings. Leave the shaft alone. Yes, it will not be perfect. But will be better…Dave
 
The bores always wear egg shaped. If you just ream the hole and press in a bushing, the center of the throttle shaft will shift because the reamer follows the "center" of the egg shaped hole. This means the relationship between the throttle plates and the bore is hosed up. Also relationships between butterfly and any idle or transfer ports is messed up too.
What this means is you have to find a way to locate the center of the unworn portion of the hole and then BORE a hole ON that center.
then you can press in a bushing and ream a hole to size.
This is not beginner machining, this is journeyman final exam level work.
 
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