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Coilpacks and spark plugs
r1_pete - 10/10/10 at 06:29 PM

Doing a bit of fine tuning on the jaguar, now I have the edis6. coilpack and map mjlj, set up with the SU carbs.

I noticed that with the timing light on a lead one half of each coil, the flash was consistent, on the corresponding 'opposite' coil (the one energised at the same time) the flash was inconsistent, this was the same for each of th three pairs of coils.

This got me thinking, should I have changed the plugs from the BP5ES' I was running with the electronic distributor setup, I seem to remember reading resistive plugs should be used with a coilpack setup?

Looking for some help from those who understand these things as to if I should change, and what the resistive equivallent is to a BP5ES.

Cheers.
Pete.

britishtrident - 10/10/10 at 06:50 PM

I wonder if it is a Spark polarity issue upsetting the timing light.

The non-ressistor plugs should not be an issue.
Ressistor equivalent plug is wait for IT --- BPR5ES

[Edited on 10/10/10 by britishtrident]

r1_pete - 10/10/10 at 06:55 PM

You could have a point, current will effectively be flowing in opposite directions in each pair of plugs.

I'll try reversing the timing light sensor, see if that makes any difference.

Then try a set of BPR5es'

iti_uk - 11/10/10 at 11:17 AM

quote:
Originally posted by r1_pete
You could have a point, current will effectively be flowing in opposite directions in each pair of plugs.

I'll try reversing the timing light sensor, see if that makes any difference.

Then try a set of BPR5es'


Would this really be the case? This would mean that the plugs would have to be wired in series, which is not possible given that the heads provide the common ground.

Are you sure you have the plugs gapped correctly and that the HT leads are all in good condition?

Chris

r1_pete - 11/10/10 at 11:49 AM

Yes, each end of each HT coil connects to a plug lead, hence when that coil fires both plugs do, hence the term wasted spark, and one plug is on the +ve side of the coil, the other being -ve.

boggle - 11/10/10 at 02:26 PM

is this not the same principal as the rover v8?

iti_uk - 11/10/10 at 04:57 PM

quote:
Originally posted by r1_pete
Yes, each end of each HT coil connects to a plug lead, hence when that coil fires both plugs do, hence the term wasted spark, and one plug is on the +ve side of the coil, the other being -ve.


Ahh, so the circuit goes;

GND -> -ve -> +ve -> GND

Where the GND to -ve is across the first plug, and the +ve to GND is across the second plug, the -ve and +ve voltages being equal and opposite, the potential difference being created by the firing coils.

Is that right?

Chris

[Edited on 11/10/2010 by iti_uk]

r1_pete - 11/10/10 at 06:03 PM

Thats basically it, this is the interal wiring on the coils, the bottom coils are the LT the top the HT, A A B B C C are the plugs.

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