Author Topic: fuel linkage adjustment detail point (Read 17447 times)

Cees Klumper · « **on:** August 03, 2007, 17:04:00 »

At the tech session, at least one car's air intake flap in the throttle housing would not open all the way, even with the gas pedal pegged to the floor. One possible cause is that the gas pedal travel needs adjustment, which was the diagnosis at the time.

However, upon returning home, I checked mine. Sure enough, the flap does not open all the way. The cause however is not that the pedal needs adjustment, but that the FI pump lever hits its 'full throttle stop point' before the throttle flap does!

The FI lever and the throttle flap each start simultaneouly from rest. Apparently though, the FI lever reaches 'Max' appreciably before the throttle flap does.

I looked at and fiddled with the set-up for a while, lengthening and shortening the various connecting rods, but to no avail. I am probably missing a very simple correction, and would like to know what it is ... anyone have a clue? If the throttle flap is indeed opening too slow in relation to the FI pump, then that probably causes a too rich fuel mixture at anything above idle (unless the FI pump's partial and full load screws are adjusted appropriately, which I doubt). Could that explain relatively high gas mileage?

An easy fix would be to move the baljoint at the end of the lever that connects to the throttle flap a bit more inwards, so that the same movement of the gas pedal results in more response from the air flap. But there has to be another way I am guessing.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

Benz Dr. · « **Reply #1 on:** August 04, 2007, 22:50:54 »

It's not supposed to reach full opening. There should be about a 1 mm gap when the linkage is fully opened. The full stop screw can fool you sometimes because it may be in or out a ways from where it screws into the housing. If it's sticking out 3 mmm there will be no gap at all and if it's missing the gap could be 3mm. This amount is of little bearing on the performance of the car as long as thre is some amount of gap at the full opened position. If you have the base settings correct with both levers opening at the same time it will work right and the lever won't come all the way to full stop on the air control housing anyway.
Base settings are the important thing here.

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061

Cees Klumper · « **Reply #2 on:** August 05, 2007, 00:20:01 »

Thanks Dan. On mine that gap looks to be about 3 to 4 mm, so maybe I will still fiddle with it some more, but I feel better now.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

Shvegel · « **Reply #3 on:** August 05, 2007, 00:52:17 »

I remember from my racing days that 80% open on a butterfly valve flowed the same as 100% open. Remember you have the throttle shaft in the way no matter what so ir really doesn't matter if it is open to the last mm.

I am sure Mercedes wanted a tiny bit of slack in the linkage to keep from stressing the linkage and wearing out the throttle body and shaft which would cause unwated air leaks.

As Long as the throttle is still closing all the way there is no harm in tightening it up a little just don't over do it and always check it after any other linkage adjustments

ja17 · « **Reply #4 on:** August 05, 2007, 06:42:21 »

Hello Cees,

It's only when the venturi and the injection lever are both lacking travel, that a significant power loose is noticed.

Start off making sure that the injection pump to cross over rod linkage is correct at 233mm center to center. Then adjust the others as needed.

Joe Alexander
Blacklick, Ohio

TheEngineer · « **Reply #5 on:** August 05, 2007, 09:32:50 »

It will open more when you use the "kickdown".

Cees Klumper · « **Reply #6 on:** August 05, 2007, 15:24:23 »

quote:
Originally posted by theengineer

It will open more when you use the "kickdown".

Thanks Engineer. Actually I check the travel by moving the linkages by hand, standing over the engine. So the pedal travel, and the kickdown switch, don't really figure into this one, unless I am mistaken.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

Benz Dr. · « **Reply #7 on:** August 06, 2007, 12:07:52 »

One trick I use to set the throttle linkage is to hold my finger on the injection pump lever and watch the throttle valve as it moves. It's impossible to watch them both at the same time so the injection pump lever is by feel and throttle valve by sight. The closer they open at the same time the better your off idle response will be.

Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061

TheEngineer · « **Reply #8 on:** August 06, 2007, 15:08:41 »

It's these tricks of the trade that are most helpful and they are hard to come by! Thank you Dan Caron! I set my linkage to the 10mm bore in the support installed on the intake manifold. Made a 10mm pin from aluminum (aluminium to you, Cees)leaving a small raised sharp point in the center. Then set the ball to that, and adjusted the rod to the venturi just right. When I set the vertical rod to my injection pump it comes out to 229 mm instead of 233. The car runs better that way. Before, I set the vertical rod to 233mm and adjusted the length of the other rods to fit. As I recall, there is also a graduated disk available, like a protractor, that is fastened to the pump lever and another one to the venturi. The relationship of degrees is given in the manual. I saw one case where a specialty shop (tune-ups & fuel injection work) rebuilt the cylinder head and could never get the car to start or run. The linkage was mis-adjusted.

'69 280SL,Signal Red,Automatic,retired engineer, West-Seattle,WA

66andBlue · « **Reply #9 on:** April 09, 2008, 22:08:12 »

By reviving this topic I would like to start a survey on the length of the different linkage rods in our members' cars.
So whenever you have a chance, please measure these rods - from the center to center of the ball sockets. Already in this thread we have two measurements for the IP rod: 233 mm and 229 mm.

In addition it would be good to know where exactly the venturi rod is attached on the cross over rod:

As I understand it the hole in the concave bracket that holds the cross over rod is used to align the ball but how far is the ball away from the hole?
I am not sure whether it makes a difference but include whether it is a 230SL, 250sl or 280SL.
Thank you all!

Alfred
1966 blue 230SL automatic

J. Huber · « **Reply #10 on:** April 10, 2008, 10:15:44 »

Hey Alfred. Well, to the best of my measuring (and to be honest with this, there is some +/- of a mm) -- mine looks like 148mm for the centermost rod and 297mm on the throttle one. As for the distance of the crossover linkage from bracket to edge -- I show 23mm. My car's end bracket looks a bit different than yours (besides looking about 40 years older...)

Download Attachment:

link.JPG
65.21 KB

James
63 230SL

merrill · « **Reply #11 on:** April 10, 2008, 18:33:24 »

Cees,
I believe the bbb has the degrees the throttle body and inj pump open and their relation.

I need to check, however, I think the tb never opens to 90 deg.

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

jwalk · « **Reply #12 on:** April 11, 2008, 19:50:11 »

This is a first time for me. I applaud all responsible for this site and the WIFI Manusl. My car is a 65 230SL 5 speed. It runs reasonably well, but even though it starts without problems, I have been unable increase the idle speed above the 500 RPM peg. I have adjusted the idle air on the intake manifold in conjunction with the fuel screw on the FI to the point that I no longer know the reference point. If six clicks = one turn, how many turns are possible? With all the adjustments I have done I have not accomplished the 700-800 rpm called fore. Let me say that the distributer is VFUR6 51 retard,the intake throttle is matching, the linkage throttle to FI is set to specs. How do I return the fuel setting to the nominal or default position?

Thanks in advance for all help.

PS. I have a Three page installation instruction by BOSCH that might add to yuur data base. With direction I would gladly copu it to you.

66andBlue · « **Reply #13 on:** April 11, 2008, 23:34:49 »

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jwalk

... I have adjusted the idle air on the intake manifold in conjunction ...<hr height="1" noshade id="quote"></blockquote id="quote">
If you changed the stop screw on the Venturi valve then this could perhaps contribute to your problem.

This topic contains some useful information on IP adjustments:
http://www.sl113.com/forums/index.php?topic=4156
You might also want to read and follow these instructions: http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Linkage
Also look at the diagrams and pictures here:
http://www.sl113.org/wiki/pmwiki.php?n=Main.Engine-starting-aid-tour

Let us know how it works out and welcome to the group!

Alfred
1966 blue 230SL automatic

jwalk · « **Reply #14 on:** April 12, 2008, 12:42:48 »

quote:
Originally posted by 66andBlue

quote:
Originally posted by jwalk

... I have adjusted the idle air on the intake manifold in conjunction ...

If you changed the stop screw on the Venturi valve then this could perhaps contribute to your problem.

This topic contains some useful information on IP adjustments:
http://sl113.com/forums/index.php?topic=4156
You might also want to read and follow these instructions: http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Linkage
Also look at the diagrams and pictures here:
http://www.sl113.org/wiki/pmwiki.php?n=Main.Engine-starting-aid-tour

Let us know how it works out and welcome to the group!

Alfred
1966 blue 230SL automatic

jwalk · « **Reply #15 on:** April 12, 2008, 13:05:07 »

quote:
Originally posted by 66andBlue

quote:
Originally posted by jwalk

... I have adjusted the idle air on the intake manifold in conjunction ...

If you changed the stop screw on the Venturi valve then this could perhaps contribute to your problem.

This topic contains some useful information on IP adjustments:
http://sl113.com/forums/index.php?topic=4156
You might also want to read and follow these instructions: http://www.sl113.org/wiki/pmwiki.php?n=Fuel.Linkage
Also look at the diagrams and pictures here:
http://www.sl113.org/wiki/pmwiki.php?n=Main.Engine-starting-aid-tour

Let us know how it works out and welcome to the group!

Alfred
1966 blue 230SL automatic

glennard · « **Reply #16 on:** April 12, 2008, 19:54:49 »

Cees, The BBBs have correlation tables for throttle valve and control valve angles starting with the 220SE.

jwalk · « **Reply #17 on:** April 12, 2008, 20:42:52 »

Thank you Alfred for the response. To clearify things, the throttle is normally closed with just a hint of intereference when opening with the throttle rod disconnected. With a 10mm Pin & .375 bore in the end to allign the cross shaft crank ball pin, the throttle rod properly fits between the two fixed balls.The length of the pump shaft does fit so that the throttle crank and the pump cranka are against their fixed stops.If the throttle stop was mis adjusted would not the result be increased RPM ? Another pussle to me is that the idle air screw does not bottom out and restrict air flow nor does it stop the engine when completely removed. Note that with best effort the idle is smoothe and vacuum is steady. The RPM, at 500 is too low.

66andBlue · « **Reply #18 on:** April 12, 2008, 21:18:11 »

Hi jwalk,
I am sorry but your problem exceeds by far the tiny bit I know about linkages and injection pump settings. I had hoped that the link to the IP topic would provide the answer for you.
Surely one of the experts will chime in soon and give you some cogent advice.

Alfred
1966 blue 230SL automatic

hands_aus · « **Reply #19 on:** April 13, 2008, 05:55:31 »

The injection pump rod should be adjusted first and should be 233mm long, centre to centre. Then the throttle rod, then the other rods.
Yes and both injection pump and throttle body levers should be on their stops.

When I adjusted my linkages I found that the vertical rod that goes down to the accelerator pedal linkage (mounted below on the engine block), was touching the inlet manifold. This in effect was being used as a linkage stop.
It also made it impossible to adjust the tuning at idle.
To check this linkage use your torch to see if it is free of the inlet manifold when you have finished your adjustments.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
BEST OF THE BEST!

jwalk · « **Reply #20 on:** April 14, 2008, 12:08:53 »

Hi Alfred,

I am still working with my idle problem, however I thought to take this opportunity to provide some numbers. Because my SL does have the 10 mm reference hole in the intake manifold, I used that as a start point. The result is 130 mm center to center between the FIP arm ball and the cross arm lever ball. Next with both the FIP arm and the throttle valve arm at their respective stops, the result is throttle rod 277 mm center to center. Because the bracket which mounts the cross shaft to the intake manifold is different on my SL from that shown on your post, I have not attempted details. Since I have edited typo's I thought I might comment on the differences I see in numerous quotes concerning the length of the connecting shaft from the FIP to the cross shaft. Is it 133 MM or 130 MM, and is the length common for 130, 150, and 180 SL's. My BBB, Passenger Cars starting August 1959, does address the 230SL in detail but does not mention any lengths for FI connection links.

jwalk

white 65 5 speed

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Author Topic: fuel linkage adjustment detail point (Read 17447 times)

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