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Discussion Starter #1
With the immense help of fellow Alfa BBer Davo54, over the last two days, we changed the motor mounts and intake plenum rubber runners on my '83 Spider.

After putting everything back together late yesterday afternoon, I fired up the car, and it immediately went into fast idle. After a minute or so, the revs dropped to the point where it wouldn't idle any longer.

When I was re-assembling everything, I noticed that the horizontal linkage rod from the firewall had fallen to the right side of the plenum support rod (between the bracket and inner fender). Since the plenum support bracket had given us so much trouble, rather than removing the bracket, we unscrewed the horizontal throttle linkage rod.

I am assuming that in removing the linkage rods, the setting changed. What is the procedure for adjusting the two engine bay rods (horizontal and vertical). Also, is there a baseline measurement for the distance between each ball socket?

As you can see from the photo, the OVS was removed.

Thanks!
 

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There is no real baseline length for the rods. It's all relevant to too many other factors.

Ideally you would remove both rods, set the idle on a warm engine using the idle bypass o-ring, then set the short rod so that it allowed full closed and full open of the throttle plate when the bellcrank is rotated, then screw the pedal stop in the cabin all the way down, back the floor stop up as neccisary to prevent bind between a fully pressed pedal and carpet, then set the long rod so that it to made full throttle with pedal down against the stop.

A little short in description and definitely doesn't cover the actual patience needed to get it just so, but more or less the way its done. Two people make it easier, but it can be accomplished with creative use of a brick, board or bit of string.
 

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Discussion Starter #3
Hmmmm. The engine was idling correctly prior to changing the engine mounts and removing the throttle rods, so I'm a bit hesitant to start messing around with the idle by-pass "O" ring.
 

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This really sounds like an air leak issue. Make sure you put all the vacuum hoses back on in the correct locations. You can find a diagram on the L-Jet diagnostic page in Tifosi's post.

It's also possible one of the vacuum lines was damaged during this operation, and you just didn't notice it. It's pretty easy to do.

Greg,
Silicone Hose Kits
OKINJECTORS.COM
 

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Discussion Starter #5
Yeah, I also thought it was an air leak, and double checked the line from the plenum to the vacuum sensor (under the washer bottle), which has fallen off in the past. All the other ones appear to on correctly.

I was just thinking that it was idling correctly before I started this project, and that two of the four plenum runner rubber hoses were leaking pretty badly, so replacing all four with new silicone hoses might be affecting the idle. I will just go ahead and replace vacuum hoses as required, renew all the oil vapor separator hoses, install my super clean OVS, and then adjust the idle speed "O" ring (along with installing new "O" ring) as Tifosi mentioned above, and later the throttle linkage.

Thanks again, especially for the Bosch L-Jetronic page!
 

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With the car being an 83, you probably will need to be replacing the throtle linkage ball joints on both ends of the vertical throtle link. I have an 88 and I looked at mine while changing my motor mounts - they are falling apart. IAP has them. I ordered a pair but have not replacsd them yet. While you are down there working with that link bar, this would be an excellent time to renew the link bar ball joints at the same time. Might save you doing the same job a second time down the road.

Robert Hill in Memphis, TN
 

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Discussion Starter #7
Thanks vf31hill, I just ordered a couple linkage clips along with a new idle "O" ring.
 

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There you go. It's always good to plan ahea

d.

Robert
 
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