SPARK PLUG GAP

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SPARK PLUG GAP

Postby Hubert64 » Wed Apr 25, 2018 1:27 pm

Hello,

Experiencing very difficult starting when cold with my HA 1965 although everything is new (delco, coil without ballast, spark plugs, fuel pump, points and semi electronic ignition (a kit I bought and installed - I keep the points but the condenser is disconnected - it is a kind of relay - with that system, a very small current passes through the points)), an electricity specialist attributed the problem to an insufficient spark at the spark plugs. Starting when the engine is hot has never been difficult. Starting when cold was difficult even before the electronic ignition, which induced me to install this.

I think this is possible because once, my dynamo broke down and I managed to drive home with the battery but impossible to drive faster than 45 mph because the engine was very irregular. As the dynamo wasn't working, there wasn't enough current to deliver a sufficient spark.

The electrician advised me to narrow the gap at the spark plugs by 0,2 mm, thus from 0,8 mm specified by Vauxhall to 0,6 mm. I've tried and the car started after the third time, which was much better than before. I drove about 3 miles and everything sounds ok. The idle is perhaps very slightly less smooth.

I would like to know if any other Vauxhall owner has experienced such a problem and if there is a danger for the engine in the long run with the closer spark plug gap.

Thank you for your attention.

Hubert.
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Re: SPARK PLUG GAP

Postby 1972nail » Wed Apr 25, 2018 3:43 pm

Sounds about right, weak spark.

What's causing it? Is the new Delco coil one that should have a ballast and you've just removed it? If it is you would be better off with a proper non ballast coil - Lucas DLB105

Is the electronic unit working properly? Check it is by replacing it with points, condenser and original coil with ballast.

Does the electronic unit control coil dwell? If it does then is the dwell long enough to charge the coil sufficiently between firing? If dwell isn't adjustable then you need a very low resistance coil specially designed for electronic ignition like the Lucas DLB198.

If the points still control dwell are they set correctly as per the manufacturer?

Running with a weak spark and a closer gap will do little harm but your fuel consumption and emissions will rise and you will have less power.

Check for good earth connections at the block, battery, distributor, electronic unit if it has an earth and any others you can find. Also check that the ignition timing is correct.
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Re: SPARK PLUG GAP

Postby Hubert64 » Thu Apr 26, 2018 8:04 am

Hello 1972Nail,

Thank you very much for your very precise awnser. I will try to investigate the issues you suggest this week end.

Truly yours,

Hubert.
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