W111 and others split linkage test

[jim 56]

Hello all I would like to know is this correct.A idle when I split the linkage, if I move the venturi linkage slightly the car will want to stall.When I move the pump linkage slightly it also wants to stall.I don't know if this is right but I think so I'm guessing this means it is balanced.BTW it is a M130 engine in a 1072 280 SE.

[wwheeler]

That seems a little odd in that usually at idle, these engines run best just slightly rich. Normally, giving it just a bit of air would result in very slight up tick in RPM. Whereas adding fuel almost always results in the idle dropping slightly. In either case, it should not want to stall, just drop the RPM slightly.

Of course I have a ‘68 and do not have the electronics in the ignitions that the later cars have. Maybe they are different?

[jim 56]

thanks I read that they do run rich but I can't seem to get it any richer.I have quite a few shims under the BC.I'm going on the road next week and will pull plugs when done and see.

[wwheeler]

When I said the engines run rich, that is primarily at idle. In the other higher ranges, it leans out. Keep in mind that the BC changes the mixture for all RPM ranges including idle speed. In the idle speed range, there is a seperate adjustment on the FI pump. If you want to change the idle speed mixture, the knob on the back of the FIP is what you want to use. Do not adjust when the engine is running though. Bad things will happen!!!! The split linkage test is most effective for idle speed but can also be used for RPM ranges higher than that.   

Checking the plugs would give you an idea about the mixture for all ranges, not just idle. So I guess you need to determine where you think the mixture is off. As a general rule, you want to make sure ALL of the tuning is done first (plugs, points, timing, valve adjustment, throttle linkage etc..... ) before addressing the mixture. Then I would start at the upper ranges first by using the BC. Then focus on the idle and finally the mixture when cold by using oval shims on the WRD.   

You might want to mess around with the FIP tuning simulation in the tech section. It will help understand how all of the functions of the FIP effect fuel mixture.

[jim 56]

Thanks yes I went thru all the other things (valves plugs linkage tour I did put Crane system in.)I will run it this week and report back.

[wwheeler]

This is one of the issues that affect W11X cars and W113 cars. Engines and the fuel systems are the same. So why this site is so valuable to us and you could post this on in the fuel section and maybe get responses from others who are more experienced.