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Injection pump timing question

Posted: 02 Nov 2014, 17:50
by dekhelia
Finally bought a dial gauge, as I've known for a while (ever since the installation of the AAZ engine a couple of summers ago, in fact) that the injection pump timing is incorrect. It's possible to get a workable setup by locking off the cam, crank and pump at TDC on no.1 cyl, and of course the engine will run fine. But I've found that I have to always use the cold start to get it to run evenly. Notwithstanding the fact that the pump is actually too far advanced ... but I suppose that's another story. Hence the purchase of a dial gauge.

The thing is, when I measure the lift of the pump, I'm getting a reading that is way advanced: 3mm of lift, where the correct reading should be 0.8mm (give or take 0.03mm).

I can back it off a little, by rotating the pump away from the engine, but I still can't get the right measurement, as the pump comes up against its furthest possible amount of travel - as it's restricted by the position of its retaining nuts and bolts at the front.

So my question is, what do I need to do to get more adjustment?

Re: Injection pump timing question

Posted: 02 Nov 2014, 22:16
by Timburrows
Possibly the timing sprocket on the nose of the crank has moved hence pump timing out at tdc,not unknown to move if bolt has become loose then re tightened before it completely foookedthe key way may be???????

Re: Injection pump timing question

Posted: 02 Nov 2014, 22:48
by ELVIS
WHS^

Friday had the exact problem.

Trying to fettle pump timing, turning engine backwards on crank sprocket to set DTI, no change?!?!?!?

Was using a deep ring spanner and thought maybe I was being a biff and spanner wasn't seated, double checked them realised I was undoing a very loose bolt. Took off bottom sprocket and key way on crank/sprocket is absolutely battered :(

Oh well, half eight tomorrow morning is still a few hours away :mrgreen: :ok

Re: Injection pump timing question

Posted: 03 Nov 2014, 12:02
by dave friday
You are checking it at top dead center? or perhaps the reading your getting is the total reading!

Re: Injection pump timing question

Posted: 03 Nov 2014, 17:55
by dekhelia
Thanks for the replies, chaps. Seem to have sorted it now.

First off, I wasn't reading the dial gauge correctly: I was thinking that each gradation on the dial represented 0.1mm ... whereas each one actually represents 0.01mm. So the reading of "3mm" that I was panicked about was actually 0.3mm.

After that it took a fair while to work out when to zero the dial. In the instructions I had (from vince waldon's site, an excellent source of technical stuff) I was taking the the 'roll-back' of the crank too far before zeroing the dial gauge. You only need to roll the crank backwards an inch or two away from TDC, zero the dial, and then read off what you get when you crank fowards to TDC. Pretty straightforward in the end. Just takes a few goes to get the hang of it (for me, anyway).

Re: Injection pump timing question

Posted: 03 Nov 2014, 22:12
by dave friday
Good you've sorted it out! It took me a while to get the hang of it too.