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Discussion Starter #1
So the throttle on my '71 1750 was really sticky, especially when the engine was cold. It was undriveable: the engine would keep revving even after I lifted my foot from the accelerator. I identified the cause as a stiff or sticky short link. (That the root of the problem is in the throttles is unquestionable. When I pull that little plastic clamp from the short link off the bellcrank, the bellcrank springs back beautifully.) So, I yanked the throttle bodies out of there and concluded that the spindle on which the butterflies and synch lever are mounted was really gummed up. I dumped both throttle bodies into a degreaser and within about a half hour, the stickiness was almost completely gone in one throttle, but still existent in the other. They are just really dirty. But, I want to clean them out more thoroughly. So, now I'm trying to dismantle the throttles completely so they can be properly cleaned.

That's when I encountered some problems. If you look at the throttle body, the spindle that mounts the butterflies is locked in with two small roll pins on either side (mine are impossible to punch out on account of rust and I've already broken two 1/16" drill bits inside the roll pins!:(). Photo 1 below is close-up of the offensive roll pin. But, even if I get those punched out, the spindle will not come out, obviously, without removing the throttle butterflies. How in THE heck do you take the butterflies out?

Each butterfly is attached by two small brass screws. Once I get the screws out, though, the fit of the butterflies in the body is so exact that they get jammed when trying to slide them out. I'm not forcing them, because I don't want to mar anything. I succeeded in "tickling" one of the butterflies out, but the other won't extricate. Photo 2 below is shot showing one butterfly out. I am able to move it around a bit (i.e. I can spin it), but it is a tough cookie and won't come out. Also, I've noticed that the body is beveled inside -- more narrow toward the ends that attach to the air box -- so I'm aware the butterflies must come out the other end. But, they still won't obey.

Any thoughts on (1) punching a very seized 1/16" roll pin and (2) more importantly, getting the butterflies out?

I've searched unsuccessfully for this solution, but none appears. If this thread is duplicative without my knowing, please let me know and I'll pull it.


Thanks.
 

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I don't think this subject has come up before. I personally don't recommend that the throttle bodies be disassembled because of the things you're running up against, although if badly corroded, you might now have a choice. When re-assembled you have to be absolutely sure that the butterfly screws are staked/locktite'd so there's no possibility that they could back-out and be injested by the cylinder.

If you're about at the end of your ideas on removing the stuck screws, consider taking it up to a good machine shop and see what they can do.

While it's easy to do, I recommend you change the small seals at the end of each shaft.
 

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Butterfly Catastrophe!

This is a bummer.... Trying to drive out that little &*%$! roll pin described above has resulted in catastrophe!!! Either (a) the rod that holds the butterflies in place (on the end of which is the offending roll pin, see photos) or, more likely, (b) the throttle body itself ...

...has bent.

...
...
...

...NOOOO!!!!!

The butterflies are flightless. They won't close all the way and, I am one *very* sad jackass moron right now. I think the aluminum throttle body got ever so slightly flattened, maybe in the vice (try not to scold me, I know) preventing butterfly closure.

Now what? ...Other than "walk."
 

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I feel your pain. I was recently replacing a suspicious shaft and seals on carburetor and ended up bending the new shaft pushing it in. That was $40 thank you very much... . I learned there was a good reason to use copper when tapping in something like a shaft...
 

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Here's another good source: Alfa Parts Exchange APEDIRECT.COM

This is a bummer.... Trying to drive out that little &*%$! roll pin described above has resulted in catastrophe!!! Either (a) the rod that holds the butterflies in place (on the end of which is the offending roll pin, see photos) or, more likely, (b) the throttle body itself ...

...has bent.

...
...
...

...NOOOO!!!!!

The butterflies are flightless. They won't close all the way and, I am one *very* sad jackass moron right now. I think the aluminum throttle body got ever so slightly flattened, maybe in the vice (try not to scold me, I know) preventing butterfly closure.

Now what? ...Other than "walk."
 
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