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Old 01-17-2021, 06:21 AM   #1
TouringMusician
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Default 1976 Kjet Altitude Adjustment

Howdy, yíall! So I bought the 76 245 that was on CL in Portland last week, road tripped up to my friendís garage in Washington to tune it up and get it ready for the trip, and Iím currently driving/camping my way back to Colorado. I just got my first real elevation of the trip (Deadman Pass in eastern Oregon), and the idle is now hunting around unhealthily in the 600rpm range, almost stalling. Iím guessing as this Kjet system doesnít have any external input source, I need to adjust for elevation as if I have a carb, but my massive green Kjet book is thoughtfully at my house in Colorado, and a quick search hasnít helped me find anything helpful yet. Iíve driven tons of carbed cars up and down all sorts of elevations, so I understand the principles at play, I just have never tuned a Kjet car before.

So my questions are:

How do I adjust mixture? (Or do I even need to, as the car is running fine at speed?)
How do I adjust idle speed? (Is this as easy as the stop on the throttle cable?)

Thanks, and sorry for the novice questions, I just have no resources here driving a car I flew in to buy haha.
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Old 01-17-2021, 02:17 PM   #2
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Below is from CI system greenbook. it appears WUR is responsible for altitude compensation.

On B21 F USA Federal 1976 and 1977 models with altitude compensated controi pressure regulators the contral pressure varies to an extent dependent on the prevaillng air pressure, see diagram.
The diagram is basad on air pressure at sea level, and up to altitudes of approx. 600 metres (2.000 ft) O.e. 947 mbars.
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Old 01-17-2021, 02:46 PM   #3
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There should be a black plastic knob on the throttle body that is used for adjusting the idle. In most cases, the idle stop set screw doesn't need to be adjusted.

You can adjust the fuel mixture with a 3mm Allen wrench at the fuel distributor, but if the car was running okay before, you shouldn't need to as the WUR is supposed to compensate.
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Old 01-17-2021, 03:40 PM   #4
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Thanks for all this! The WUR doesn’t seem to be very happy but the car runs great other than idle, so I’ll just touch the plastic screw and not fix what ain’t broke.
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Old 01-17-2021, 04:03 PM   #5
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OP, I experienced the same symptoms many years ago with my first Volvo, a fuel injiected 142: everything was OK til I got into thinner air at the top of the North Cascades Hwy., at which point it crapped out and barely ran.

Scared the hell out of me, but it calmed down and returned to normal once i got down to a lower altitude.
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Old 01-17-2021, 10:41 PM   #6
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How long has it set before you purchased it? Old-bad fuel? Poor injector pattered?
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Old 01-23-2021, 08:47 PM   #7
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So the car runs awesome here at 6200ft, but I can smell that itís a bit rich, and Iím getting only 20-22mpgs. I was thinking it could probably do mid 20s? Iím gonna try leaning out the Allen screw here just a tad and see what that does. The WUR is a big question mark, as it clearly wasnít operating correctly with bad cold running issues, but we wired up a momentary switch to fire the cold start injector to start the car, and that system seems to work perfectly. Push the button while cranking, fires immediately, and after 15-20 seconds, itís fully drivable without any hesitation. Idles a bit high until it warms up, but that would make sense if itís too lean when itís cold, and the mixture is closer to correct once itís warm.
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Old 01-27-2021, 12:35 AM   #8
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So I can’t seem to figure out the mixture adjustment-there seems to be a hole between the fuel distributor and metering plate, but when I stick a 3mm Allen down there, nothing seems to bite...
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Old 01-27-2021, 12:52 AM   #9
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May I assume you didn't find the rubber plug with a metal handle inserted into the hole?

It is not uncommon for the plug to be AWOL and this allows dirt to accumulate inside the pocket where the allen wrench goes. Spray some carb clean in the hole and use a metal pick or a piece of stiff wire to work the dirt loose a couple of times and if you have compressed air, you can blow into the hole to try to dislodge some of the dirt.
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Old 01-27-2021, 09:57 PM   #10
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I probably have everything you need to swap it to Lh2.
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Old 01-28-2021, 04:32 PM   #11
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^Another possibility is that someone installed the anti-tamper ball used on the later K-Jet cars here in the states...
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Old 02-05-2021, 04:42 AM   #12
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Quote:
Originally Posted by 2 old for this View Post
How long has it set before you purchased it? Old-bad fuel? Poor injector pattered?
I was also wondering about this. I've driven K-Jet cars on long trips through mountain passes without any issues.

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