Linkagetourproblem

[450sl]

Last of the few jobs before finishing my 1970 manual 280 is the Linkage tour

Have replaced all my linkage balljoints , set up the main linkagerod
to its zeropoint  , put the IP Rod to 233mm (perfectfit),
adjusting  Venturivalve rod and setting valve  just from binding.

Now I run into a problem:
The travel of the IP linkage  limits the Venturivalve to open for just only 90%.

How do i address this problem ?
I have disconnected all the rest of the linkage , only main Rod , IP Rod
and  Venturi Rod are connected.

Have adjusted the final linkagearm off the venturivalve to rest to its stop max,
So when disconnected it opens/closes max.

Any suggestions are very welcome
Thanks
Mark

[ja17]

Hello Mark,

Are you saying that the stop on the IP pump keeps the linkage on the venturi from moving to its most open position?

[450sl]

Hi Joe, Yes iit does

[wwheeler]

Joe is the expert here and may correct me if I am wrong, but I believe when the IP linkage is on the stop, the venturi linkage is 1 mm off of its stop. So, the venturi shouldn't be hitting its stop. It is in the BBB somewhere.

I think the reasoning for this is that the linkage has some play and tolerances and it is impossible that both would hit on the stop at the same time, 100% of the time. So I guess they feel that the IP hitting its stop is the most important.

[450sl]

Well , Its about  5mm off its stop..........


Now wondering if the valve in its closedposition has sunk deeper into the housing due to wear. 

Do these valves/housings tend to wear over time ?

The BBB says to check with graduated discs ; since i dont have them avaiable : is there an easier method to check?

[wwheeler]

5mm sounds like too much. Graduated discs are getting way out of my comfort zone. Might check for bent throttle rods also.

When the linkage is at the idle position, is the venturi on it's closed stop when the IP is on it's closed stop? They should be. You can adjust the sockets on the rods to achieve this. Then the ratio of the arms should allow the venturi to be just barely off its stop when the IP is wide open.

[Benz Dr.]

I ran into this sort of problem recently. The setting of 233mm is actually too long. I set the rod from the cross shaft to the injection pump to this lenght and found that it wouldn't line up with the alignment hole on the bracket attached to the intake manifold. I asked Hans about this and he said that setting won't work with the fuels we have today and that the alignment hole is the way to go.

 A small gap at full throttle is normall. Try setting your linkage so that the ball head at the intake manifold end is dead center in the middle of the alignment hole. This will make your IP rod shorter than 233mm. The corellation betwen the IP and the throttle body is critical and any small change will affect how lean or rich your engine will run at various speeds. The throttle valve and IP open at different rates but will be the same when fully opened at around 82 degrees IIRC.

[450sl]

I have previously set my linkage to the aligment hole , and the IP rod is--- wont believe it-- EXACTLY  233mm.... (replaced tje 2 bearings and most balljoints)

I have set the final linkagearm on the airvalve to the max in idle position in order to achieve Max travel.



May i conclude from your reply that in my case its best to go for lets say 231mm to achieve that more travel at the airvalve?

Or: because i have a spare 280se engine available , should exchange airvalves to see what it does to the linkage?

[450sl]

Problem solved,

Took off the final link from the valve and compared it with my spare one : turns out that PO had replaced the balljoint (that original is riveted to the link ) ,but bolted it just offsett the org. 50mm center to center .

[450sl]

ThankYou Guys..

[Benz Dr.]

That's all it would take. Make sure you have your throttle plate adjusted as described in the linkage tour.

[stickandrudderman]

This is where the wide band O2 sensor really comes in handy. You can see instantly if your linkage is off.
I had a 220 the other day that was perfect at idle in P but terrible at idle in D. The solenoid was working fine but a little play in the linkage was enough to make the mixture go weak as soon as the solenoid opened the throttle valve. The tiny play in the linkage meant that the pump linkage was lagging behind and it was really evident what was going on with the AFR display.

[450sl]

widebandkit sounds good , can you recommend a particular one ?

[stickandrudderman]

I used these people:

http://www.efi-parts.co.uk/index.php?productID=204

Nice guys and the kit does what is needed.

[Cees Klumper]

In the US this same sensor kit costs around $160 (£102 rather than the £155 price in the UK).

In France, Germany or Netherlands anywhere from €200 to about €350.

So depending on customs rules cost-wise iit seems best to order it in the US and have sent via USPS.

I am totally unfamiliar with this whole topic of 02 sensors, will start a new topic next.

[450sl]

Got my kit in today : have removed my complete exhaust system today : Stickandrudderman can you recommend a position to mount the sensor ?

[stickandrudderman]

Anywhere in the down pipe where it is accessible is fine, Just make sure that the sensor is angled downwards in order to prevent any moisture accumulating within it.

[450sl]

Thanks,   Is it necessary to be as close as possible to the headerpipes or can it be located lets say near the rear muffler ?  (Temperature wise)

[GGR]

distance from exhaust valve as well as angle are important. Do some reading first on the net, it will help you find the best spot on the car. I went through this on another car so it can't really compare to the Pagoda, and I don't remember exactly the details. On my V8 car the sensor is kind of 1 meter down the closest exhaust valve. this is because I have a tri-Y system and putting it more upstream would have read only two cylinders. As it is it reads mainly one bank of 4 cylinders, but being downstream of the balancing pipe I guess it also reads a bit of the other bank. On the Pagoda you may be able to fit it a bit closer, but you will read only out of 3 cylinders. My sensor is angled 45 degrees upwards, ie wires come at the top of it.

[450sl]

Realize that all typical locations are a compromise in a way, thats why i would very much appreciate details from other users.

I  am no control freak , i just aiming for a decent overall  air/fuel  indication