Distributor type fuel pump

[kalindi]

After deciding to keep the relatively old BMC engine and see how I get on with I spent yesterday getting familliar with the various systems, fuel, water etc. The engine has a Lucas CAV type distributor pump and thre appeared to be a very small ammount of diesel arround what I took to be a bleed valve. This is a bolt on top of the pump with a lock nut to prevent movement, the one of the flats on the head of the bolt has a small hole drilled into it. So I slackened off the lock nut and tightened the bolt only to find that you can screw it a long way further into the fuel mpump body. So it doesnt appear to be a bleed valve at all but on looking at a diagramme of the pum, which I know I should have done before touching it, it seems to be some form of hydraulic damper on the governor. Screw it right in and once started the engine remains at those revs not matter what you do with the throttle, screw it right out and the when the throttle is put in the idle position the revs drop to just sufficient to keep the engine running. At positions in between returning the throttle to the idle position and the engine will slowy reduce revs until some fairly constant speed dependant upon the actual position of the bolt. I now know I should not have touched in the first place but having said that what is the best way to adjust it and why is the slight evidence of diesel a cause for concern.
As usual many thanks in advance of advice. /forums/images/graemlins/confused.gif

 

[Refueler]

Oh dear - sounds like you've adjusted the Anti-stall device. If I'm right this is the adjustor that when you shut throttle from full open to idle - it stops the engine cutting out.

It has an air-vent screw into the anti-stall body.

It's normally factory adjusted and not for us to fiddle with ... Mine is actually sealed with a wire and lead seal. I have a Perkins but on top of pump is a similar affair.

Local engineer when I had trouble with the pump removed the seal and adjusted it - he knew what he was doing and now I have an emgine that runs far sweeter than ever.

He did it by opening throttle making sure it opened fully, then closing it ... checking it didn't drop very low then cough and pick up ... he adjusted it till he reached a nice close of throttle. He then set idle rpm and did it all again .. balancing idle rpm and the adjustment to aim for a sweet open / close and idle.

The Perkins instructions, which the pump is a CAV may help, but n promises !

Slacken Locknut to enable anti-stall body to be unscrewed to mid point.
Adjust idle speed to about 625 - 650 RPM
Screw down anti-stall body until slight increase in enginer speed, bring back half a turn and lock with locknut.
Open throttle with NO load to max, bring back to idle. If return to idle takes more than 2 - 3 secs then body has been screwed in too far. If engine stalls or near stalls body hasn't been screwed in enough.
Repeat until happy medium achieved.

Hope above helps ... I know a boat who's Beta engine did same and above solved his as well !

 

[omega2]

What you are going to have to do is this, undo the lock nut and unscrew the bolt, then when you are happy she will keep running take for a run, and whilst running when warmed up open throttle full, check on exhaust is it coloured? if not open the screw until just a slight wisp of black smoke is detected, then lock it up. What you have been playing with is the regulator, and you are lucky it has not had a run away, in which case you would not have been able to stop the engine. I think I have a diagram of the pump in question I will post for you, but the diesel suggests that the cam box need draining and refilling with engine oil.

 

[omega2]

This should get you out of trouble.

 

[oldharry]

Hang on Omega2, this is 4cyl BMC with a CAV distrbutor type pump. Your diagram shows a 6cyl in line pump. A very different beast! The CAV distrubutor pump is self lubricating and doesnt have oil reservoirs.

 

[omega2]

Are absolutley sure? I know the drawing is a six but the four is the same just short of two. Lets wait until he has had another look eh?

 

[kalindi]

Thanks for everyones advice so far and for taking the trouble to send drawings etc. It is certainly a Lucas distributor pump and not an inline one.
I am hoping that as I got into this problem while adjusting this then I can get out of it without touching anything else. If I alter the slow speed setting etc. I think it might make it a bit more complicated to fix.

 

[oldharry]

[ QUOTE ]
Are absolutley sure? I know the drawing is a six but the four is the same just short of two.

[/ QUOTE ]

Yes I am. The Lucas distributor pump is completely different, looking similar to the distributor on a petrol engine, and Kalinidi confirms this is one. I have had 2 BMCs, both fitted with them, and know the anti stall adjuster screw he undid. It looks just like a bleed screw, and Refuellers post shows the right way to set about sorting it. And I agree with Refueller it's a job for a trained mechanic - fiddling with it is very unlikely to get it spot on again.

 

[omega2]

Sorry for the confusion, my intent was to assist, I bow to your superior knowledge Harry.

 

[oldharry]

Learned it the hard way! They are a bit like the old Seagull outboard - a good one was worth its weight in gold and went on for ever. A bad or neglected one was not even much good as a mooring weight. I had one of each. Learning curves at times were vertical - specially at sea 300 yards off a rocky lee shore with an engine that had stalled and refused to start again.