Cleaning carbs without toxic chemicals

[lostviking]

Here's some before and after action. The surface has been sprayed with carb cleaner to displace the water, then PB Blaster to keep it from rusting right away.

 

 

Edited March 31 by lostviking

[lostviking]

To repair the thottle shaft wear, after measuring it's in the cast iron part, the shaft doesn't have any real wear. I bought some 5/16 ID, 3/8 OD bronze bushings and a 3/8 reamer on Amazon. It has a flute area longer than the carb diameter and a nice long shaft. I can stick it through the two holes in the carb base to align things and ream "backwards". The bushing are smooth, so I will use some JB Weld steel repair to epoxy them in place. After they are completely cured, I'll use another 5/16 reamer to align bore the bushing, just in case there is any issues. I'll check the throttle shaft first and if it's easy to go in and fits freely, I won't do the final ream.

 

Should end up with a nice tight rebuild on this one. I cleaned all the linkage up with some wire brush heads and my Dremel. I'm definitely going to take the bottom off the other carb and do this also, as it still has some rust and can get rid of. I'll just need to replace the butterfly screws again.

 

Pretty much wraps up the rebuild thread for the carbs. After that I just need to put them on my AoK intake and fab the linkage. I'll just model mine after what George does, because that works fine.

[Eneto-55]

If your bronze bushings are "oilite" or sintered bronze, it's not advised to ream that type of bushing.  (I know, not a high speed spinning shaft.)  I would suggest finding a shaft the right OD, and long enough to go all of the way through, so that this rod can be used to keep the two bushings aligned while your epoxy cures.  

 

(Oh, and ideally there would be around .002 'interference' between the OD of the bushing, and the ID of the bore.  So a reamer of about 1/64 less would be about right, I think, without doing all of the conversions.  The bushings are probably also about .001 over the nominal OD size.) 

 

DISCLAIMER: I am not a machinist, so take it all with a grain of salt.  But I do have the Machinery's Handbook that my son used when he was doing machinist training, and have done a fair bit of reading-studying in it.

Edited April 1 by Eneto-55

[lostviking]

Oilite bushings are almost alway ream to fit. IDK where you see someone saying to not ream them. Take a look at the Practical Machinist or a bunch of other sites regarding reaming bushings.

Spec is .001, not .002 which is probably fine, but looser than one of my carbs is now.

It's doubtful I'll need to do anything after installation due to the method of installing the bushings.

 

 

Edited April 2 by lostviking

[lostviking]

The bushing I purchased came in over size and I won't use them. I just stepped away from the lathe, making my own. I turned the OD to .376, which I can reduce if I need to, but by freezing them I think I can put them into the cast iron (which I'll heat). That should give me a nice tight fit. I'm going to drill the ID just under and them ream using a .310 reamer. That should give me .001 (or .0005 on each side) and a pretty much perfect fit.

I used standard bronze, because we have it and because this is almost a static surface for a throttle shaft. Either way, it's a lot less severe of an interface than the shaft against cast iron.

Now I just need to turn a shaft long enough to go through both sides of the body, to use as an alignment tool for my drill press. I'll have it in the DP vise, clamp it and use the "tool" to align the body perfectly. Then just swap the "tool" for the reamer. Then I'll have two perfectly aligned .375 holes to push the bushing into.

[lostviking]

Just bought a .3105 reamer to finish this off. Then I'll just cut a couple to length.

 

 

[Eneto-55]

On 4/2/2024 at 2:21 PM, lostviking said:

Oilite bushings are almost alway ream to fit. IDK where you see someone saying to not ream them. Take a look at the Practical Machinist or a bunch of other sites regarding reaming bushings.

Spec is .001, not .002 which is probably fine, but looser than one of my carbs is now.

It's doubtful I'll need to do anything after installation due to the method of installing the bushings.

 

 

Machinery's Handbook.  They do say, however, that if it is necessary to ream sintered bronze, to use a very sharp tool that has the cutting edge cut in a certain way, and (if it is to be used for a fast & constant rotating shaft) to recondition it (I cannot recall the exact term they used) by heating in a pot of oil, or something like that.  (I don't have time to look it up in the book right now.  I also saw similar notes on-line, as I recall.) 

 

Like I said, I'm not a machinist, so (as "Oklahoma's favorite son" always said) "I only know what I read in the newspapers."

[lostviking]

Books are good.

Edited April 7 by lostviking