Could someone with experience confirm what ignition timing should be?

Here is what I see in the manual:

Ignition timing: 18 degrees at 2000 rpm (for US models, vacuum disconnected) and advancement curve is represented in this table:

rpm adv
6400 9
5200 8
3500 6.5
2000 5
1300 3
1100 1
900 0
700 0
500 0
300 0

So, if at 2000rpm advancement should be 18 deg, then the complete table is like this? :

rpm adv RESULT
6400 9 22
5200 8 21
3500 6.5 19.5
2000 5 18
1300 3 16
1100 1 14
900 0 13
700 0 13
500 0 13
300 0 13

Basically, if I use strobe to check my timing(with vacuum disconnected) - my timing should match the RESULT column at each RPM?

Did I get it right?

 

The ignition timing on your car is controlled by a sensor that reads off the front crank pulley. Nothing to adjust. Are you sure you are not looking at the V12 figures?
Greg

 

Hi Greg, I am looking in the manual for 3.6 6 cylinder engine. Timing table is from repair manual, I just want to make sure I am interpreting it right. Pretty sure I am, but wanted to confirm.

I do not know (yet) how timing is done on this car, I assumed that distributor has those weights inside that spread as RPM rise (I assumed mostly because there is a vacuum tube going to distributor which also adjusts timing based on engine load, pretty standard old-time setup)

Thank you.

 

Inside the dizzy there is a rotor arm and nothing else much, as far as I can remember:
http://www.jaguarclassicparts.com/uk...utor-3-6-litre

The timing is mainly controlled by the ECU from a signal sent to it from the sensor on the crank pulley, plus from the throttle angle, temp sensors and other things like that. There may be some sort of counter weight timing-modifying stuff in the dizzy, but I cannot remember seeing on mine (now long gone) but if there is, unless it is jammed or the springs shot, I doubt it will be the cause of any out of spec timing.
A very good plan to check the timing though, but I do not quite understand your second table. Are you 100% sure you are looking at the right engine? I think, repeat think, assuming that the table is for the AJ6 3.6 litre engine, and that the test for the timing being correct you quote is correct, that you should find an 18 degree spark advance BTDC at 2000 rpm, vac disconnected (if there is one). After that, the ECU etc does the rest, and it is not, in principle operator adjustable. Could easily be wrong though, so I look forward to finding out from you!
Greg

 

My vin is in 119xxx series, you are looking at (V)139052 to (V)179736 range.

This is what they have for older models: ScanFile 2002 v6.0 but they do not show inside the distributor(below base plate). I am happy there are no points there :-)

I am sure I am looking at right table. I did not quite like the way they presented data, I would prefer table that shows final advancement figures (like the second table I did, one for US and one for EU), but I guess the way they did is better when calibrating distributor off the car.

The reason it all started is because I feel like engine is not performing that well. 3.6l engine should be real thrill to ride, mine is just fine... I was happy to find $19 strobe on amazon and checked what I have - it is off. It is pretty close at 2000rpm but otherwise it is way off.

In old days distributors had weights and two springs, one softer that would work lower half of the curve and one stronger that would take over after. Over time they would stretch and adjustment (usually bending the hook where they connect) would be needed. My car's timing kinda looks like that - is sits at about 7 degrees on idle then shoots to about 18 at 2000, weak springs would do that.

That's my theory... let me get distributor off and we will know the reality.

Thanks for the input!

 

All as expected, now it's "trail and error" (in addition to epoxying piece I broke while taking thing apart)...

The good news is that second(stronger) spring in fact is not engaging at all over the full range of weights motion (it is bad news, but at least it justify the effort), also pickup circuit is barely moving on the base plate (lubrication is all dry) - I bet vacuum adjustment was not working either.

I would really appreciate if anyone has any suggestions on how to calibrate/tune the thing while it is off the engine.

Thank you!

 

The stronger spring may be designed not to engage in the first part of the travel. thanks for the interesting post and pics.
greg

 

Correct, but in my case it does not engage at all, once I got it all clean it is very easy to see.

Because distributer rotate 6 times slower then engine I adjusted table to distributor rpm, also expressed advancement as % of total travel, here it the table I am going to use to tune distributor:

rpm adv %
1067 9 100
867 8 89
583 6.5 72
333 5 56
217 3 33
183 1 11
150 0 0
117 0 0
83 0 0
50 0 0

basically weights should stay in place until about 150 rpm and then should move about 11% of the travel by 183rpm... and so on... reaching 100% of the travel by 1000rpm.

The biggest challenge now - how to adjust springs? There is no lip to bend.

For the luck of suggestions how to tune the thing I am already coming up with 'ingenious' design of my own involving:
- white dot on the weights(so I can see dot move as thing spins),
- dremel(to spin, I happened to have one with variable speed)
- piece of plastic that I screwed on the side in such a way that runner(rotor arm) hits it and makes sound.
- computer and speaker: I found website online Online Tone Generator - Free, Simple and Easy to Use. where I can hear the sound of any frequency(rpm).

So my plan is to tune my 'slapping of the piece of plastic' into sound of every frequency on the table and observe where the dot is in relation to it's full range of travel... this is not very accurate but the best I could come up with... I will check the end result with the strobe light on the car.

But first I am going to somehow confirm my math, other engines with similar bore/stroke should have similar advancement table. Just want to double-check...

It may sounds like I am having fun...

 

Naaah, It is almost a black art. Timing needs are far more than similar bore and stroke. Cylinder head design, cam timing, compression ratio, manual or auto box, etc. As many combinations as there are stars in the sky.... Oh, and fuel blend at the time. Here we have winter and summer blends. Oh, not to mention Ethanol!!!!


In olden days folks messed with timing and advance rates. Spring selections were sold. Slots were elongated or shortened. It all starts with static timing at rest.


The advance read strobes are fun. In the absence of a dynometer, the ear and seat of the pants help. or the drag strip and timing devices.


Have fun, just don't put in too much advance and blow a hole in a piston or two.


Carl

 

Thanks. I had my fun for two days and getting tired of it.

I definitely need new springs... was able to 'tune' lighter spring pretty close but had to cut off one ring. The stronger spring is stretched and lost it's 'spring'... On top of all my strobe was only good for 5 min and then died, now need find new one to finish.

In conclusion - this is not a DIY job without proper equipment.... I would spend my time better by looking for ecu-controlled replacement system.

here is a good writeup if anyone is interested: http://mgaguru.com/mgtech/ignition/p...lucas_dist.pdf

Cheers!

 

In the olden days, the right way was a Sun distributor machine.
Chuck the unit in place and spin it. Sans cap. Read advance & dwell under various RPM. Set to spec's or mess around.


Nowadays, a good strobe and a tach work well.


Test? As stated before.


Or,just refresh the stuff in the distributor and it
will be quite close and drive well.


Messing with static is easiest. Runs best just short of ping under load.


Carl

 

'Because distributer rotate 6 times slower' - that was a mistake, distributor rotates half speed of engine... I corrected it right away in my table, just wanted to 'correct' it here as well :-)

got new strobe - sears! works much better so I should be done with this soon.

 

6X? yeah, I wondered. am I about to learn something......


But, no matter, it is the marker on the dampener and when #1 fires
and is lit by the strobe that counts.


If the HT leads are on the cap and plugs in the correct firing order
they have to follow.


Same for static. Time #1 and all others are in. Cam & distributor rpm's not an issue.


Have some more fun.


But, yeah it isn't fun when the tools go bust.. Warranty on the bust strobe? Or just toss it...


Carl

 

i altered my advance curve, and cleaned out dizzy, bought small spring an weight kit,Universal type(fits all), trial&error till it worked out fine. V12.

dizzy spring kit from Summit racing (cheap).

by the way, i did not like the factory ignition curve,or total amount, i now run 20* initial 950rpm , and all in at 4500rpm 50*, bear in mind my engine is aV12 Jag., 9.2-1 pistons.