carb rebuild question, throttle bearings Options

[tat2dphreak]

ok, my set of weber 40s... they are old(built in the early 80s by his estimation). my mechanic cannot replace the throttle bearings and thus, they do not idle right once the engine gets warm, it's like they are always slightly "cracked" open, when warm.

is there a place that can rebuild these and make them "new" again? or is it time to start carb shopping?

fron what I understand, the new carbs have a plate on the front, and one on the back that can be removed to replace the throttle shaft bearings, but this set only has 1 plate, so the bearings are not replaced(at least by normal means)

[Van]

If the 40 IDFs are manufactured like the 44 IDFs (and I think they are), there are no bushings. There is just a long "bore" that the throttle shaft goes through, where it's supported on both ends by a sealed ball bearing.

This bore is a pretty close fit to the shaft, so it minimizes air leakage into the carb throats - but, if your throttle shafts are straight, there should be no wear in this bore. And, even if there is a little wear, that's what the air adjusters (#37) are for.

I believe you mentioned before that you have some kind of slop or play that's causing the butterflies to be "sucked closed" - that could only be caused by a loose throttle linkage, or by a loose actuator arm (#17).

It's also possible that the bores for the bearings (on either side of the carb housing) have worn a little bit. I saw that on one of my carbs - the bearing slid in and out with no friction. But there wasn't enough play to cause the butterflies to move on their own. That carb had a slightly bent shaft, and I think that was the root cause. Anyhow, I straightened the shaft and used a very thin piece of shim stock (0.001") to make the bearings snug in the housing - just snug enough so I had to tap them in with a hammer. This way, the outer race of the bearing is stationary with the carb housing, and the inner race will turn with the shaft - providing "ball bearing-ness".

I don't want to say anything bad about ACE, because I've never used them - but, after taking my carbs completely apart, inspecting them and learning how they work, I have no idea what "bushings" they're talking about.

I can see how other brands, which don't use ball bearings, use some bronze or bass bushings to support the throttle shaft - and to replace those, one has to first machine out the old ones and press in new ones (like valve guides in a head). But, my Weber 44 IDFs don't have anything like that.

[ME733]

If the 40 IDFs are manufactured like the 44 IDFs (and I think they are), there are no bushings. There is just a long "bore" that the throttle shaft goes through, where it's supported on both ends by a sealed ball bearing.

This bore is a pretty close fit to the shaft, so it minimizes air leakage into the carb throats - but, if your throttle shafts are straight, there should be no wear in this bore. And, even if there is a little wear, that's what the air adjusters (#37) are for.

I believe you mentioned before that you have some kind of slop or play that's causing the butterflies to be "sucked closed" - that could only be caused by a loose throttle linkage, or by a loose actuator arm (#17).

It's also possible that the bores for the bearings (on either side of the carb housing) have worn a little bit. I saw that on one of my carbs - the bearing slid in and out with no friction. But there wasn't enough play to cause the butterflies to move on their own. That carb had a slightly bent shaft, and I think that was the root cause. Anyhow, I straightened the shaft and used a very thin piece of shim stock (0.001") to make the bearings snug in the housing - just snug enough so I had to tap them in with a hammer. This way, the outer race of the bearing is stationary with the carb housing, and the inner race will turn with the shaft - providing "ball bearing-ness".

I don't want to say anything bad about ACE, because I've never used them - but, after taking my carbs completely apart, inspecting them and learning how they work, I have no idea what "bushings" they're talking about.

I can see how other brands, which don't use ball bearings, use some bronze or bass bushings to support the throttle shaft - and to replace those, one has to first machine out the old ones and press in new ones (like valve guides in a head). But, my Weber 44 IDFs don't have anything like that.

....................VERY well done.....May I add,... that IF the return spring, on one end of the butterfly shaft is not ...rewound/reinstalled/properly,OR the securing end for the spring ...has been altered....thereby allowing less return spring tension...then the butterflys could have NO tension at the closed position....AND VAN...where did you get the screws (diagram #40)for your butterflys when you reinstalled them were they steel or brass?.

[Van]

where did you get the screws (diagram #40)for your butterflys when you reinstalled them were they steel or brass?.

I used steel ones (with an allen head, not a sloted head). I also used loctite on them.