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setting timing.

Posted: 24 Oct 2019, 07:49
by bigbadbob76
So I went to check the timing on my DG engine last night.
Using the Itchy method on the Wicki.
At 900 rpm ish with vacuum pipe off the dizzy and choke off.
My timing jumps around between 0* BTDC and about 7* BTDC.
It was a bit off before I tweaked it (about 3* to 10*) and now accelerates better and doesn't pop when over-running.
My question is- is it normal for it to jump around like this? if so, do you try and set the average position to 5*BTDC, the peak to 5* or the minimum to 5*?

Re: setting timing.

Posted: 24 Oct 2019, 08:25
by bigbadbob76
ah... ok... answering my own question here but it might help others. :wink:
https://www.gowesty.com/tech-article-details.php?id=162

this is for setting total advance, tencentlife suggests reving until timing stops advancing, approx. 3500-3800rpm on a DG engine. and setting timing to 35* at this RPM.

Re: setting timing.

Posted: 24 Oct 2019, 08:39
by Mocki
It shouldn’t be jumping , and a DG should be 5° as per the pulley markings

10° is too much for a DG on unleaded

Re: setting timing.

Posted: 24 Oct 2019, 08:55
by bigbadbob76
Thanks Moki.
Hmmm.... I wonder why mine is jumping around erratically.
AFAIK I don't have the idle stabiliser module fitted.

Re: setting timing.

Posted: 24 Oct 2019, 08:59
by Mocki
No a DG wouldn’t have a ISU so you can’t unplug it !

Whiteout knowing what kit you were using it’s hard to guess , but I would take a stab at the signal from the plug lead might not have been stable

Does the engine speed. I’ve up and down accordingly or is it stable ?

Re: setting timing.

Posted: 24 Oct 2019, 12:26
by bigbadbob76
Sealey standard strobe powered from separate battery. maybe the strobe is erratic not the timing. :?
Revs stay stable on the tacho but it does sound like it's hunting slightly. not really noticeable unless you listen carefully.
I'm not overly concerned as I've got it pulling better now but would like it to be right.

Re: setting timing.

Posted: 24 Oct 2019, 12:51
by bigbadbob76
And the timimg jumps a few degrees from one rev to the next rather than a smooth/slow wander up and down.

Re: setting timing.

Posted: 24 Oct 2019, 16:27
by itchyfeet
suppose it's possible that something else on the circuit such as at tacho or a damp connection or dash BOD module is causing it, if it's a late van try and disconnect green in the black box to front of vehicle.

also possible the dizzy is worn.

Re: setting timing.

Posted: 24 Oct 2019, 16:45
by bigbadbob76
Thanks Itchy.
Worn dizzy would make a lot of sense, AFAIK it's the original dizzy, I replaced the vacuum can when I got the van but not the whole dizzy.
BOD not connected, can unplug tacho easily enough to rule that out.

Interestingly, since tweaking it last night and retarding it slightly I've not only had better acceleration but considerably lower oil temp too. water temp has remained the same so don't think it's the colder weather that's done it.

Re: setting timing.

Posted: 24 Oct 2019, 17:48
by 937carrera
Was the idle stable - if not the varying speed can change the timing due to centrifugal advance. The hunting may be indicative of a slight air leak on the induction side

If you are firing the strobe from a separate battery then I'm sure that is not the cause of a misreading

Double check you don't have an idle stabilisation unit.

Re: setting timing.

Posted: 24 Oct 2019, 18:29
by itchyfeet
I suppose ignition module could also be at fault, swap it with your spare :lol:

Then saw the dizzy with your spare :lol:

Re: setting timing.

Posted: 24 Oct 2019, 19:01
by bigbadbob76
Typically... those are the two things I havn't got spares of. :lol:
Got a spare coil but I doubt if that would make the timing erratic.
Any recomendations for dizzys? I seem to remember reading somewhere on here that the replacements are not the best.
I'm away for a week in the van tomorrow so will look into this when I get back.

Re: setting timing.

Posted: 08 Nov 2019, 12:51
by T25Convert
Assuming its a timing light with an inductive trigger, you can get this effect if you ignore the arrow on the clamp showing which way round to put it.

I don't understand why it makes a difference, but it does.

You may be more competent than my friend* though and not have made such a foolish error........

Re: setting timing.

Posted: 11 Nov 2019, 20:21
by bigbadbob76
hmmm.... I pointed the arrow at the spark plug....
I'll try it the other way round just in case.

The van made it to Lauder and back just fine and even accelerated going up hill. :lol:
So maybe I'll just leave well alone.

Having spent Saturday lying under my golf replacing the coolant pump/supercharger clutch I'm in no hurry to get the spanners out again.

Re: setting timing.

Posted: 15 Nov 2019, 20:51
by Neil74
I know it sounds a little obvious, but did you plug the vacuum hose when you disconnected it from the dizzy??
I normally use a small screw.