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)

[tat2dphreak]

cool, where did you get the bearings? also, can one get the shaft/ butterfly hard parts still or no?

right now my thought is "what do I have to lose? an afternoon?? " worst case scenario is it's not the bearings, it's the bushings in which case I'm right back to "gotta buy new carbs"

best case scenario is it might cost me $10-100 bucks in parts and kits to do these again...

[Van]

I say: give it a try yourself!

I think you can get most of the parts here: http://www.redlineweber.com/

The hardest part is undoing the screws that hold on the butterfly disks. The are usually either loctited or physically deformed so they don't vibrate out. pushing hard with a screw driver on them can cause the shafts to bend. If they're the deformed style, you can trim off the deformed part with a dremel tool - then they're much easier to manipulate.

My bearings were pretty shot - they felt dry and a bit "gritty". Ball bearings don't perform that well in an "oscillating" environment... but we have to use what we can!

[tat2dphreak]

the bearings looked ok, so I called wes, he replaced them when he was rebuilding the carbs :| but the BUSHINGS are shit. he replaced the bearings eventhough they didn't look bad. but the slop was still there because the bushings are crap...

we put together a plan tho, to make due for a little bit we'll adjust the idle down some, making it a little harder start(it's very easy to start now) but will idle lower when warm. this will do until I get the cash for a good set of used dells or the empis(still not sure I want them based on some of the things I've read)

[Van]

What number (in that diagram I posted earlier) are these bushings you're talking about. I have to confess, I don't know what you mean.

[tat2dphreak]

according to ACE, and Wes, they are somewhere in the body itself and require special tooling to remove (IMG:style_emoticons/default/huh.gif)

ACE said they can't replace the BUSHINGS on 40s, because they would have to change their "setup" (IMG:style_emoticons/default/confused24.gif) and like I said there's probably not financially enough reason for them to do that, it's already close to the same price as replacement to do a FULL rebuild...

[Mark Henry]

I've made bushings before on my mini lathe but it takes time to fit each bushing. I'd say I can do them, but cost plus shipping and it's again too much scratch.

[ArtechnikA]

Bieker can do throttle shaft bushings. I think he specialises in the Solexes the 356 guys use, but he's probably the go-to guy for this operation. He won't be cheap, but it will be right.

http://www.biekerengineering.com/

[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.

[tat2dphreak]

since the car is dry-docked, maybe I'll try to pull the shafts and check and see if the bearings are fitting tight... are there any "watchout" things that might keep me from getting it back together correctly?

[Van]

since the car is dry-docked, maybe I'll try to pull the shafts and check and see if the bearings are fitting tight... are there any "watchout" things that might keep me from getting it back together correctly?

It's pretty straight forward.

Remember to be careful not to bend that throttle shaft - it's a bitch to straighten! That also goes for the end nuts. If you can, hold that round washer part (and the linkage arm at the other end) with pliers so you don't put a "twisting" motion on that shaft.

When you put it together, remember the accelerator pump linkage... the first time I put a carb back together, I forgot it and had to pull the throttle shaft out again.

When you put the butterflies back in, slide both into the shaft (they only go in 1 direction - on my 44s, the stamping (78 degrees) is visible from the bottom (if I recall). it'll be obvious if it's not right, because the screw holes won't line up. Anyhow, put the screws in loosely, make sure you "close" the throttle so the butterflies are seated properly in the bores, then tighten the screws. It might take a few tries - so be patient. When you get it right, they close with a most satisfying "snap"! Also, you can't see any light around the edges when you hold it up to the light and try to look through.

Obviously, if you feel you need to force something, you might be doing it wrong - so stop and get a 2nd opinion.

Let us know how it goes!

Here are some pages you might find useful:

http://www.rescue912.com/spider/WeberIDF_Rebuild/

http://www.aircooled.net/gnrlsite/resource...8idarebuild.htm

[tat2dphreak]

thanks for the info, I'll keep everyone posted, of course (IMG:style_emoticons/default/smile.gif)

[tat2dphreak]

ok, who said "linkage"?

because it was the linkage, kinda...

the springs were not strong enough to really snap it shut tight.. even though there was no gap against the idle screw, I lowered the idle, and changed the angle of the carb springs to compensate for the throttle shaft being worn and having very little tension in itself.