DG Ignition timing

[hal2710]

Morning all,

I've read the wiki and I'm still a bit unsure. My 1.9 DG engine seems to have a 2.1 dizzy according to the part numbers. Is this OK ? The engine runs OK but I'm worried that the dizzy is giving too much advance.

Does anyone know in millimeters how much advance I should get with the vacuum pipe connected.

I would like to scribe a mark on the pully and then set the dizzy for max advance. The engine is a new recon from Elite VW which I am pleased with before we all go off topic.

Thanks for looking,

Mick

[Aidan]

Mick
is the vacuum advance unit dual vacuum or has the correct DG single vacuum unit been fitted ?
025 905 205 Q or 205 AE are DG disis, 205 N or 205 AF are DJ ones
I have asked Bosch dealer whether the internals are the same between DG and DJ disi and he couldn't tell me, Bosch technical dept. couldn't tell him

[hal2710]

Mick
is the vacuum advance unit dual vacuum or has the correct DG single vacuum unit been fitted ?
025 905 205 Q or 205 AE are DG disis, 205 N or 205 AF are DJ ones
I have asked Bosch dealer whether the internals are the same between DG and DJ disi and he couldn't tell me, Bosch technical dept. couldn't tell him

Hello Aidan,

Thanks for the info. I've taken the dizzy off a given it a good clean. I have found the numbers you quote on a second line under the line I was reading

My dizzy does have only one vacuum pipe and it seems to be OK. I can only suck a few times and if I check the timing while doing this a can watch the timing move. The dizzy is 025 905 205 Q.

So I have scribed a line across from the V notch on the inside to the outer side of the pulley. This V notch is 6 mm from the TDC mark. So 5 degrees = 6 mm. So now we have something to go on.

If I've understood the wiki, the the max advance mechanical plus vacuum is 18 + 16 = 34. So 5 degrees divide 6 mm is 0.83 x 34 degrees equals 28.33 mm. Or is it the other way ? Brain hurts after long night shift. Does this sound correct. Can someone check my maths please.

Thanks again.

Mick

[itchyfeet]

As you have the right dizzy and the vac seems to work why are you concerned
are there poor running symptoms?
If I remember I looked at the max advance with my gun while givving it a very good rev and it was about 40 degrees

[hal2710]

As you have the right dizzy and the vac seems to work why are you concerned
are there poor running symptoms?
If I remember I looked at the max advance with my gun while givving it a very good rev and it was about 40 degrees

Hi, itchyfeet,

Yes the engine does seem to tickover a bit low and after trying with and without the vac advance and just setting the dizzy up a bit. More like 10 degrees on tick over. I felt the van was more responsive when set without the vacuum pipe and so I was just trying to figure out how much total advance the engine should get.

My strobe gun does NOT have any timing adjustment. It just flashes. That's why I was trying to measure and mark the pulley. To see how much advance I get at max revs.


Mick

[itchyfeet]

slow tickover can be just the throttle stop position or if on LPG it can be the idle bypass on the vapouriser set badly.

measure the diameter of the pulley, circumference is 3.14x diameter.

So now you have the circumference divide it by 72 for the distance around the circumference of 5 degrees.

so say the pulley is 150mm in diameter, circumference is 471mm, so 6.5 mm around the pulley represents 5 degrees

So mark in increments and then use the strobe gun to check how far advanced.

http://www.brick-yard.co.uk/VehicleSpec ... DGdata.htm" onclick="window.open(this.href);return false;

according to the above link on the yard

vacuum advance 2-16 degrees, mechanical 24-28 at 4200 RPM so the way I read it is you could be -5 ( standard settting) +16 ( vac advance) +28 ( mechanical advance) = 39 degrees at 4200 RPM

[hal2710]

slow tickover can be just the throttle stop position or if on LPG it can be the idle bypass on the vapouriser set badly.

measure the diameter of the pulley, circumference is 3.14x diameter.

So now you have the circumference divide it by 72 for the distance around the circumference of 5 degrees.

so say the pulley is 150mm in diameter, circumference is 471mm, so 6.5 mm around the pulley represents 5 degrees

So mark in increments and then use the strobe gun to check how far advanced.

http://www.brick-yard.co.uk/VehicleSpec ... DGdata.htm" onclick="window.open(this.href);return false;

according to the above link on the yard

vacuum advance 2-16 degrees, mechanical 24-28 at 4200 RPM so the way I read it is you could be -5 ( standard settting) +16 ( vac advance) +28 ( mechanical advance) = 39 degrees at 4200 RPM

Cool, this is the info I need. Thanks. Right I'll have a measure and test and then report back.

[itchyfeet]

also in the wiki here
https://club8090.co.uk/wiki/Pe ... nce_curves" onclick="window.open(this.href);return false;