Throttle shaft leak diagnosis

onewhippedpuppy · 02-15-2004, 02:38 PM

For those of you that remember my thread a week ago, I'm pretty certain that one of my Webers on my 70T is leaking out of the throttle shaft, reinforced by everybody's answers. Keep my car from setting me on fire!
After a few days to cool off, I took off the carb in question, and after taking off the throttle return spring, I can just barely detect a little play vertically in the shaft, when pulling on the bracket where you adjust the idle. Is this answer enough, should I go ahead and pull out the shaft and start looking for bushings? I assume there should be no play whatsoever in this shaft, am I correct here? Thanks guys, hopefully this will go ok, I miss driving the car already, it's spent more time broke than it has on the road since I bought it.

vash · vash's Garage

damn, i cant help you. but i was just getting here to wish you luck. looks like we are still at it (you and me). offtopic, but the same thing happened to a jeep cj7 that i had. just a tiny bit of movement in the same shaft made it run like krap.

you could always go with CIS! jk. good luck, friend.

cliff

onewhippedpuppy · 02-15-2004, 03:01 PM

CIS?! That's just more stuff to break, and on my car, it would break.

Who wants their car to start on the first try anyway? How's your current nightmare coming along? Door still working great?

Does anybody know anything about a Weber factory oversize throttle shaft? Doing a Google search, I found a Weber blow-up listing part #s 10016.442, 10016.443, 10006.408. That was the oversize throttle shaft for both ends and the center portion. Is this a repair piece, save me the trouble of messing with bushings? Or is this just wishful thinking?

Hatari · Hatari's Garage

I had this problem on an old set of Webers. Pierce Manifolds (www.piercemanifolds.com) sells the oversize shafts and can line bore and install the new shaft(s). As I recall, the parts and labor to install an oversize shaft on the carb I had the problem with was about $125.
Jack

onewhippedpuppy · 02-15-2004, 07:05 PM

Thanks Jack, do you recall what the cost for the oversize shafts was? I'd like to just purchase the parts and have the line bore done here locally, at the least it should save me on shipping.

Zeke · 02-15-2004, 07:14 PM

I got trounced on for my thoughts on your first thread, but I'm gonna try this again. What's going to happen to the gas that is leaking out of the shaft once you get it sealed? The job of a carburetor is to atomize the fuel into a fine mist as it is introduced to the intake passage. I'm still not convinced that there should be that much raw, liquid gas present at the throttle plate. Except for the squirters. But even those should be trimmed out so there is no stumbling to acceleration.

I still want to know why you have so much gas there that it leaks out.

onewhippedpuppy · 02-15-2004, 07:33 PM

Milt, is it possible that something I did while tuning the Webers brought on this problem? I was syncronizing them as per 101 projects, and the mixture adjustment screw on the #1 cylinder (where the leak is) didn't seem to have any effect on the idle, regardless of my turning it in or out.

Zeke · 02-15-2004, 07:45 PM

Quote:

Originally posted by onewhippedpuppy
Milt, is it possible that something I did while tuning the Webers brought on this problem? I was syncronizing them as per 101 projects, and the mixture adjustment screw on the #1 cylinder (where the leak is) didn't seem to have any effect on the idle, regardless of my turning it in or out.

I guess the question is, how does the thing run? Or how is the idle? Smooth? IMO, you should get some change with the idle mixture adjustment screw.

Now my expericence is with 2bbl IDF's. My 911 has MFI, so I'm in both camps sometimes in the same week. But I don't see any raw gas and I get results turning ANY screw on the things (sometimes not too good, either).

onewhippedpuppy · 02-16-2004, 03:58 AM

It would hold a 1100 RPM idle fairly well when warm, a little lopey but not too bad for a carbed car. The mechanic that did my PPI told me that syncronizing would probably smooth it out a little, that's why I was doing it when I found the leak. Turning the mixture adjustment screw made a difference on all the other cylinders, by Wayne's book I was supposed to turn it in until it started to throw off the idle, then back it off 1/8 of a turn or until the idle returned to normal. It worked fine with all but the #1 cylinder.

john70t · 02-16-2004, 04:28 AM

As a temporary measure, can't the air correction screws can be turned out in the others and turned in on that one to balance inconsistent idle air flow in each venturi?
My engine doesn't seem to respond too much to tweaking the idle/air corrections, probably from other factors such as cylinder sealing and valve adjustment.