MGB & GT Forum

Hi Guys,
After having an go around with the car being 180* out for over 100,000 miles running Champion Iridium plugs and finally getting my Schlemmerized dizzy to work, all was well until:
1) one of the Taylor Pro silicone 8mm HT wires crapped out and then: o
2) the 2 coils that I had as spares both failed.

Now I have a brand new Lucas Sport coil(Moss) and did not really work well until I switched plugs to RN9YC plugs.
I also replaced all the Taylor wires with new Taylor HT wires.

Well I put about 300 miles on the car and he was running great until 4 days ago when a miss started, and that coincided with snow!
So I cannot test the car until the silly season is over, March or April 2017.

However I did pull the plugs after his very last run and the pix show what is going on in the combustion chambers.
The black ring is carbon and the white colour(lean mixture) travels from the center electrode right to ground .

Any thoughts on why the plugs are this colour and not the golden brown that they should be?
A couple of details; The fuel is Shell 91, and as I envisioned this was quite possibly his last run, a can of Sea Foam was added.

The air/fuel mixture is seriously lean front to rear. The heat line on the ground (bent) spark plug electrode should be approximately in the center of the electrode apex, as pictured. I suggest first checking the ignition timing as it could be really advanced, then slowly richen the air/fuel mixture until most of the "snow white" color turns tan.

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Be safe out there.
Kenny

Are you sure your new Taylor HT wires are not resistor type silicone ones? Can you measure their resistance? Most silicone ones measure 5 or 10 kOhms per wire, 5 kOhm is best (2x5=10kOhm in the loop). If you use resistor plugs like these Champion RN9YC the plug wires should have no resistance at all or at a quite low value, say below 1000 Ohms

I run your Lucas Sportscoil myself with non-resistor Champion N9YCC and silicone wires with 5 kOhm resistance in each and every wire, it suits my Accuspark points replacement unit fine

But that your B stumbles on low temps is not surprising: you are running very lean mixtures. Shell MON 91 (RON 98?) is not responsible BTW.
Whether you use high octane gas in the B is a contentious issue. I run RON 98 myself, but many others do not ....

Only 300 miles should not generate much color.
Unless of course its silly rich or burning oil.
But then those symptoms would not take 300 miles to diagnose

You are running the right heat range and you most likely don't have intake leaks or fuel delivery problems.
Both those conditions would have very noticeable symptoms that you would have mentioned.


You don't need special wires or plugs. More expensive wire sets usually last longer and $2 copper core plugs are all you need.
As already stated, don't combine resistor plugs with resistor wires.

I have run Champion, NGK, and Autolight, as complete sets and mixed. No real difference in performance but I have a favorite.
NGK.

I have replaced individual wires when they've tested bad. Auto part store, over the counter.... just match length and ends.
I carry a single wire as a spare. Long enough for any of the cylinders.

That photo looks like it was taken with a flash. The flash will "blow" the highlights. Take one in good light and post it.

Adrian

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Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.