static timing with electronic ignition

[johnhcrighton]

Static timing with 4.2 XK is 10 degrees BTDC.

With a points distributor static timing is easy to set (with a timing light connected to the LT lead and earthed - rotate distributor until points open/light goes on).

I am installing a Pertronix unit on my '66 Series 1. My hope is to get the timing close enough to start the car, and then adjust with a strobe light if necessary. However I am told that the standard method for setting static timing with points ignition does not work with electronic ignition.

Is there a particular procedure for setting the static timing with electronic ignition?

[vee12eman]

Hi John,

You will need a stroboscopic timing light. Firstly, remove the distributor, aftter marking the position it came from. Do not disturb the timing settings, I am not familiar with the XK engine as I run a V12, but it should be possible to remove the distributor complete with undisturbed clamp - it is on most cars.

Once the Pertronix is fitted (by the way, whilst the distributor is dismantled, check the weights of the advance mechanism are free to more and lubricate them well), refit the distributor, then attach the timing light and prior to connecting HT leads to the spark plugs, turn the engine over and use the flashes of the strobe to time the car in the normal manner as if running it.

If the timing looks OK, start the car and see how the timing is with it running, adjust if necessary, if not, then adjust until correct, then start the car and fine tune. You'll have to see the manual for exact methods/settings and also the manual of the strobe gun too. Dynamic timing is always superior to static timing, which only gets you into a ball park anyway, as the electric characteristics of the set up change slightly with the parts moving at fairly high speed.

Hope this helps,

Regards,

Simon

[johnhcrighton]

Simon

Thank you - brilliant! I am replacing the whole distributor, which makes the issue of initial timing more problematic.

Your solution is so obvious (now!) I am embarrassed not to have thought of it

cheers

John C

[vee12eman]

Hi John,

Glad to have been of help, but I have been thinking on this one - you will need to attach the king lead to the distributor/coil, because otherwise you won't have the impulse going through no. 1 lead (or any other for that matter), so the timing gun won't work. Of course, you could disconnect the fuel to prevent starting, but then it doesn't really matter if the car does start, although it may prevent you using too much fuel during the set up process, but a fairly simple idea to get you in the ball park, is to get the engine to tdc, firing stroke on no. 1 (you can do this easiest with the old distributor in place, using the normal timing marks and observing when the rotor arm points to the no. one lead, or by watching the valves. Another way is just to use the normal timing marks, put your finger over the spark plug hole and feel for the compression as you approach tdc when turing the engine by hand.

Once close, fit the new unit, twist until one of the impulse marks in the new distributor (equivalent to the points opening) is approximately aligned, then proceed as originally described. The engine will possibly start if fuel is on and choke out, if so, continue with timing dynamically.

Regards, sorry if my original post was slightly inaccurate.

Simon.

[johnhcrighton]

Simon

No, I think you were on the right track. It occurred to me also that the HT leads from coil and to plug(s) need to be connected for the strobe light to work. But the clue you gave me was to crank the engine without attempting to start. My plan is to remove the plugs, leave #6 connected to a HT lead, and earth that plug away from the cylinder hole. That way there should be an impulse for the timing light to detect, no compression so easy to turn over, and no start.

The new distributor is a Pertronix Ignitor - it has no marks to indicate the equivalent of 'points opening'. I think I am pretty close to having it aligned correctly, but I want to be reasonably sure it is close before trying to start the car. The procedure you have led me to will enable me to do this.

A particular attraction of this approach is that I can get the timing sorted out before I re-fit the carburetors etc (while access is so good). I should perhaps explain that I am in the last stages of converting from LHD to RHD, and so am taking the opportunity to make some other improvements (electronic ignition, rebuild carbs etc etc)

Thanks again

John C

[vee12eman]

Hi John,

One other thought, how about removing the fuse for the fuel pump (or just disconnecting it and make sure the loose end is well clear of earth?) As you say you have the carbs disconnected, this may have occurred to you, otherwise you could just catch any fuel in a suitable container, but perhaps not advisable if you have a spark plug firing outside the cylinders! Of course if the tank is empty, no problem.

Regards,

Simon.

[johnhcrighton]

Hi Simon

An excellent caution. As it happens, I have not yet installed the new loom so the fuel pump is inactive. That, however, means I have to 'jury rig' power to the coil and starter to do the job, but that should not be difficult.

cheers

John c

PS: I now realise that rebuilding/restoring or servicing Jaguars is a significant problem solving exercise. However, I am enjoying it, all the more so because so many more experienced folk are so generous with their time and advice