Electronic ignition

[horrace]

Howdy, Ive got an electronic ignition installed on horrace the 1098. The other day it started back firing for no reason. I've stopped this now....I think by running it lean. But cylinder no.3 from the front is black and not firing properly at all. If you disconnect the ht lead it doesn't sound any different.
so now I've replaced that plug (although all 4 were new a month ago) and it seems better.
is it possible that the elec ignition could be destroying the plugs (as the plugs seem to break pretty quickly) or running out of sync or are they 100% reliable and either work or don't?

[philthehill]

I would advise that as a first off do a compression check on all cylinders to determine and compare the readings - then come back on here with the results.

[horrace]

I submitted the first post from my phone and some parts didn't make much sense so I have just re done it!
Ill do a compression test and let you know. But any feedback on elec ignitions wold be good please?

[amgrave]

Personally I have not known an electronic ignition to go out of sync, it usually either works or not. It fires once for each plug so if it fires on one then it must fire on all. The cap would be the culprit if it misses firing on only one plug or the associated lead, plug cap or plug itself. The other thing as Phil says is a lack of compression on that cylinder. Find what the compression is on all cylinders and we can diagnose further.

[bmcecosse]

The 'electronic ignition' doesn't intensify the spark -it's just more reliable and doesn't eat up points and condensers. As above the problem will liklely lie in the engine. Plugs these days go on 'for ever' if you use decent ones - but don't use 'resistive' plugs if you have resistive leads and/or caps ! Check/set the valve gaps before doing the comp test.

[horrace]

So to carry out compression test, should engine be hot or cold? And how many time do you wind it over before you take a reading?

[philthehill]

A more realistic reading will be taken with the engine hot.
Take out all the plugs.
Put a brick on the accelerator pedal to gain maximum air flow into the cylinder.
Make sure that the handbrake is on and the gearbox is out of gear.
Put compression gauge to plug hole and wind over the engine on the starter motor.
Wind over until the max compression is gained.
Repeat for each cylinder and note max pressure for each cylinder.
The compression reading on the gauge should be in the range of 150 psi plus.

Put 4 squirts of oil down each plug hole and carry out the compression test again on each cylinder.
If the rings/bores are worn there should be a noticeable increase in the max compression for each cylinder.
If there is no increase - that unfortunately is a good indicator that a valve/valve seat has burnt out or the head gasket has blown.

I hope that the above is of help.
Phil

[horrace]

Well I've done the compression test and from front to back we have 190 160 190 190 all plugs were a bit sooty so I've leaned him off a bit more. I added oil to the 160 reading which went up to 200 and rear cylinder went up to 220 when I added oil.
Weirdly ever since I changed that plug and adjusted mix he sounds great.... I just don't get why the plugs break down in a month? These are resistor plugs, would that make a difference?

[SteveClem]

I think that you just get a dodgy plug once in a while. It happened to me a while back. Changed the plugs and no problem since. I'd stick with the electronic ignition,much more reliable.

[horrace]

Could it be the coil (!)occasionally sending out too much voltage and turning the plugs?

[oliver90owner]

Could it be the coil (!)occasionally sending out too much voltage and turning the plugs?

Under running conditions the coil energy is limited by the rpm and the dwell angle, so unlikely to be different unless there is an unusual distributor fault. Consult the ignition system supplier for advice on plugs would be my advice. Not all lead and plug combinations are compatible.

RAB

This thread would be better moved to the electrical section?

[bmcecosse]

Yep -that's right - the coil just sometimes sends out a high voltage peak to your #3 cylinder.... Get rid of the resistor plugs. The readings are unbelievably high for a standard engine - but it's the difference that matters. If you knock about 30/40 psi off all the readings (to make them realistic) then there is certainly something amiss with that low one.... Although strangely you say the plug trouble is with #3 - and the low readings are from #2.....

[oliver90owner]

Yes we have a disparity of problem plug/cylinder and pressures. The simple way, to resolve the issues initially, is by exchange of the (possibly) offending item to another cylinder - and noting whether the perceived problem remains with the pot or moves with the item transferred. A simple way to narrow down the diagnostic channels, before posting on a forum such as this. More precise info is good in cases where remote diagnosis is required.

RAB

[horrace]

its a 1275 head which I assume is higher compression?
yes so lower compression on no.2 but the broken plug was on no.3
I'm not so sure in a previous thread of mine I had lower readings overall and a lower no.2 cylinder... ill have a look.
Anyway my issue is why do the plugs keep breaking down..... as now he sounds pretty sweet.

[horrace]

yep here they are from a couple of years back...

No.1 190 psi
No.2 150 psi
No.3 180 psi
N0.4 185 psi

I might have done that one cold though not hot..

[bmcecosse]

Well - the 940 head could certainly explain the higher compressions - you hadn't said that before. And therefore you need harder plugs . Champion N7Y or perhaps even N6Y will be best bet - and NOT resistor...

[horrace]

That sounds worth a try,I've found them on eBay so which ones 6 or 7 and i assume these are resistor free plugs?

[bmcecosse]

Try the 7, I sometimes found the 6 would foul up on a cold start. As long as there is no 'R' in the number code they will fine.

[philthehill]

On a standard Minor Champion N9Y does it for me every time
The extended nose keeps the tip of the plug nice and clean.
A N6 is way too cold a plug in that the crud is not burnt off the electrode and can foul and lead to misfires.
NGK BP9ES is another suitable plug.
The original fitment - Champion N5 were prone to oiling up if the engine was less than perfect.
Phil

[bmcecosse]

We're not taking about N6 plugs Phil - N6Y - extended nose. but I do think N7Y will be better here. Racing plugs (N60 etc were not extended nose) - but the engine would always be started and warmed on a set of extended nose plugs. With these highish compression readings (although I'm still a bit sceptical) a harder plug IS needed here. and it explains why plugs have been only lasting a short time. Personally I avoided anything but Champion plugs - if good enough for the Works........