M130 Let’s tune it together

[mrfatboy]

My bad. I accidentally reversed what the BC adjustment does.  I removed the post to avoid confusion.

It looks like somebody has already tried to lean out the pump by reducing BC shim thickness.

Increasing shim thickness = richer
Decreasing shim thickness = leaner.

[Pawel66]

Is the BC working or is it stuck? Easy check with food vacuum box. if it is stuck in out position, it will be making the mixture rich.

Is the car running rich, normal or lean - how do the spark plugs look like? Unless you have a method of testing the mixture under load, I would check the spark plugs and take it from there. With the adjuster.

[MarkCan]

I need to wait for the engine to cool down.
Coffee time.
I thought it was a typo on your part mrfatboy.  Anyway, with all the shims but one (0.1mm) removed I see quite difference across full rpm range.
Bottom still rich but much better, idle increased to about 660rpm which indicates less fuel going in (as I’ve not touched anything else at this point)
Mid range cleaner than before and the good news is, it will cut out with the pump linkage disconnected. When set steady above 1700rpm, rpm will pickup as the mixture is leaning out.
No top end with IP disconnected.
Looks like it’s all going in the right direction.
Now, either I like it on not, I think I have to take the idle adjustment plate out and confirm is all good in there.

Pawel, plugs are as black as the soft wood chimney.
I’m working on a contraption that will temporarily extend the BC little further. I see Joe A. mention his BC extending 22mm. We are in about the same level AS therefore it looks like I may be 0.8 mm short.

[mrfatboy]

I just measured a BC of a Pump I am playing around with at the moment. It measured 21mm from tip to bottom of hex nut as in your picture. I think your BC is good 👍

[MarkCan]

I just measured a BC of a Pump I am playing around with at the moment. It measured 21mm from tip to bottom of hex nut as in your picture. I think your BC is good 👍

Thank you.
I did check an the BC reacted to the pressure change. Let’s cross it of the list as well.
I drained the oil from the pump and removed the idle screw plate as I said I’ll. The inner screw was out of range for the springs to relay any clicks. I drove it in and out couple of times to confirm proper connection and get the better feel for the resistance it has.
After putting the plate back on thumb screw engagement is now very pronounced as are the adjustment steps/clicks. To avoid another disconnect of the adjustment screw if we can call it that I set the screw 3 clicks in (clockwise, rich) from the point of no click feel.

[Pawel66]

There is an oring there between this wider part of the screw and the plate, inside. When you press the screw, you will see it. Check it or, best, just replace it. Otherwise oil may be dripping from the screw on the, if I remember correctly, oil filter housing down there.

[Benz Dr.]

If you lean out your pump by turning the BC, the idle mixture knob will likely need to be turned to get your idle back. If you can no longer turn the knob any further out then a BC or rack adjustment should be made. I just wish I knew about this stuff years ago because it probably would have saved a few pumps from being rebuilt.

[Benz Dr.]

When your IP mixture is out a long way, big adjustments will have only small effects. As you get closer to the ideal mixture a click at the back of the pump one way or the other can be easily noticed. The IP is a very accurate system and you can get very fine adjustments with it. I start with three clicks at a time, which is a half turn, and then slowly move to a click either way.