Join Date: Jan 2003
Location: Rapid City SD, Black Hills of South Dakota, Queens NY
Glad to hear you found a serviceable pump. Be sure to keep it well lubricated in the logic section and the filter clean in the pump section. Also, I strongly advise using Marvel Mystery Oil or some other upper cylinder lubricant in the petrol.
It sounds as if the TA is weak and leaking and causing an overrich mixture. The small piece of a Monty manual I have says the dummy TA is 29mm, so that would mean that the actual should extend 29mm at 175F. You can try using your present TA by getting the engine to 175F, then using the adjusting screw under the TA to set the pump gap between the reference screw and the throttle lever at .5mm clearance. If you run out of adjustment before you can get that gap, then you can either temporarily insert a small 2mm extension onto the TA or temporarily install a dummy TA. Using a dummy TA temporarily is ok . . . you just won't have the warmup enrichment.
As far as adjusting the mixture, that's the LAST thing that is done, and that is done exclusively with the FCS. The short version of tuning is:
1. Adjust throttle relay crank stops. Idle stop - crank perfectly level. Wide-open-thorttle - 73 deg from idle stop.
2. Adjust pump gap, rod disconnected. .05mm gap
3. First adjustment to throttle butterfly master throttle bores, then syncronize with others. All throttle plates should be exactly the same. The manuals show the use of a Uni-Syn throttle synchronizer. With the throttle relay crank sitting on the idle stop, the throttle butterflies should have only .03mm open . . . essentially "just" closed. ALL idle air is supplied by the idle air distributor on th back of the engine.
4. Adjust throttle rod (relay crank to injection pump throttle lever), engine at operating temperature, adjust rod so that a .5mm pump gap is retained.
5. With engine at operating temp, and all other adjustments done, adjust the screw on the idle air distributor to achieve an 800 rpm idle speed.
6. Adjust the FCS to achieve a good mixture. Plugs tan and clean, with just a very slight hesitation when you crack the throttle open suddenly.
Before you start changing and throttle synchronization or stop screws, check twice. Chances are they're ok where they are now. You may want to make a dummy TA to help with the tuning, or as a temporary replacement if you have to send yours out for a rebuild. There's a previous thread on the BB on how to make one out of a bolt, 2 nuts, and washer.