Author Topic: Confused about the "Linkage Tour"...  (Read 317 times)

teahead

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Confused about the "Linkage Tour"...
« on: July 13, 2019, 21:36:32 »
I'm stuck on part 1 if you can believe it.

I video'd my confusion here:

https://www.youtube.com/watch?v=WBIvJQUm-oI&feature=youtu.be
1970 280SL auto, AC

ja17

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Re: Confused about the "Linkage Tour"...
« Reply #1 on: July 14, 2019, 06:05:57 »
The "slip joint" is the sliding segment of the linkage rod. Only later USA emission cars with automatics used this additional dash pot and sliding linkage rod to help regulate idle as engine vacuum changes. Engine vacuum variations occur for various reasons at idle (automatic gear selection, use of power steering, ignition timing changes and switching on A/C. The dashpot helped regulate the engine idle during these instances.  The dashpot should be removed, or moved out of the way to set the slip joint. When the engine is off and dashpot is removed, the slip joint should be fully collapsed (linkage rod short).The other linkage adjustments (IP rod length and venturi stop) should also be set with the dashpot off or moved out of the way, on these versions.  Once the dashpot is installed and adjusted correctly (with engine at idle), it will only move the venturi open since the slip joint does not allow the movement of the rest of the linkage.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

teahead

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Re: Confused about the "Linkage Tour"...
« Reply #2 on: July 14, 2019, 07:20:46 »
Great, helps immensely.

So, proper order would be?

1) adjust venturi stop screw with slip joint rod and dash pot removed

2) put rod back on and adjust.  Fully collapsed meaning adjust the length so there is no slop?  Adjust while idling?

3) put dash pot on and adjust while idling in neutral, then pit in gear to see if it moves 1mm?
1970 280SL auto, AC

ja17

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Re: Confused about the "Linkage Tour"...
« Reply #3 on: July 15, 2019, 05:57:26 »
Sounds like you have a good plan.  Keep us up to date.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

teahead

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Re: Confused about the "Linkage Tour"...
« Reply #4 on: July 15, 2019, 19:10:05 »
Sorry, I'm still confused (dense for sure).

The "Linkage Tour" states:


Disconnect the linkage rod going from the cross over rod to the venturi. If you have a USA version with the vacuum dash pot, you will need to move it out of the way so it does not interfere with the adjustment. The small slotted venturi set screw must be backed off enough to allow the venturi valve to close all the way and then adjusted in just enough to keep the venturi valve from binding in the intake.

USA 280SLs had an "Vacuum throttle control" on the intake venturi linkage. A special linkage with a "slip joint" was also used between the venturi and the cross-over rod on the engine. Adjust the slip joint linkage so it is fully compressed with the engine running and warm at idle in neutral. Adjust the vacuum control/linkage to
zero clearance. Now with the transmission in gear, the throttle lever will open 1.0 mm to 1.5 mm.




After I do (1) above, do I put BACK the dash pot before I adjust the slip joint to be fully compressed (step 2)?

Also, the dashpot...when is it in gear, does the adjusting screw push out or pull in?  I guess I can remove it, but keep the vacuum connected and see how it operates while running/putting it in/out gear.
1970 280SL auto, AC

teahead

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Re: Confused about the "Linkage Tour"...
« Reply #5 on: July 15, 2019, 19:20:19 »
Okay, from this screenshot, it looks like after I removed the dashpot to do the venturi stop adjustment, I put back everything to adjust the slip joint and dashpot screw:

1970 280SL auto, AC

ja17

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Re: Confused about the "Linkage Tour"...
« Reply #6 on: July 19, 2019, 08:18:43 »
I think you got it!
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

teahead

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Re: Confused about the "Linkage Tour"...
« Reply #7 on: July 19, 2019, 15:52:11 »
What I still don't understand is what do they mean by the slip joint being "fully compressed" at idle.

Should say, "adjust the nuts so that there is no play (as in the video) in the rod."

I did that and now the engine doesn't bog when I step on the gas.
1970 280SL auto, AC

kampala

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Re: Confused about the "Linkage Tour"...
« Reply #8 on: Today at 09:00:00 »
“Compressed” is smaller than its opposite, “expanded”

If slip joint is compressed, the rod is shorter (smaller)
If slip joint is expanded, the rod is longer.
Oz
Paris France & California
250sl - later - manual
280sl - 1971 - Auto - Limited Slip Diff.