MGB & GT Forum

I have been having a misfire problem with our '77 MGB on start for about a month until I changed the spark plugs last week, now all is well......no misfire, starts right up. At the same time the car was experiencing a run-on problem, so I filled up with a tank of 93 octane. Run on disappeared!! Now all the cars needs is a good OD and cruise control.



Edited 1 time(s). Last edit at 2015-11-25 08:48 PM by Kats Bee.

BP6ES
NGK7333

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1957 Series 1 Land Rover electric VEHICLE CONVERSION

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BP6ES...gapped at .035in.



Edited 1 time(s). Last edit at 2015-11-25 08:56 PM by Kats Bee.

Smart move, not expensive, and it is fixed.

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1977 MGB Red 'Victoria' and 2018 Jaguar XE 'Meghan'
All Classics:
Married, 2 children, MG MGB May to December, Jaguar the rest of the year.

Never had a bad NGK plug in almost 50 years.

Never had a bad Champion plug in 44yrs. Just curious Rick, I know NGK has been making spark plugs since 1936, but in 1965 there were very few, if any Japanese cars driving around the US, where'd you find NGK plugs back then. You were obviously a very early adapter, Tim

I did have bad Champions. I only use NGK, AC, or Autolite.
.035 is pushing it for points. Depends on the coil. .025 spec for Lucas coil. Hey, whatever runs for you.

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Cogito ergo sum periculoso

This has just inspired me to buy some new plugs as I have no idea when they were last fitted. Maybe it'll make my car run like magic.

... Wishful thinking?

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If it could be better, it's as good as broken.

Scott,
Why is .035 pushing it for points?

Spec for his car called for .035
Thousands upon thousands and thousands of MGB's called for .035

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LNDRVR4X4.COM
Home of Project "INCARN8'


1957 Series 1 Land Rover electric VEHICLE CONVERSION

FIXITUPCHAP.COM
FIXITUPCHAP INCORPORATED

RD3 Radar/ Electronic Warfare Technician
VIETNAM 1969-1972



Edited 1 time(s). Last edit at 2015-11-26 11:10 AM by ohlord.

Apparently BMC didn't think so....

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

Yes, the later non-points electronic ignitions.

Run what you want. As I said, it depends on the coil.

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Cogito ergo sum periculoso

I second the NGK choice. Autolite plugs are poorly made. The center electrodes are always off center and I have had issues with them in other vehicles.

As with all things, plug gap is a compromise.

The wider the gap, the more reliable the firing of the mixture, BUT the voltage needs to be higher to jump the gap, causing the HV side of things to be higher stressed and more likely to break down.
I suspect that going from 0.025 to 0.035 had to do with improvements in materials for the HV parts.

Of course the coil needs to be able to produce a high enough voltage to jump the gap.

Herb

Champion fell out of favor, in the late '70s, due to improper labeling of their heat ranges. A lot of engines suffered holed pistons due to the error. When I worked as a mechanic in a motorcycle shop, we carried a motorcycle made in Spain called Gas Gas. They came from the factory with Champion plugs, but every single one of them failed before we could deliver the bike to the customer. We carried NGK plugs exclusively. The only defective plug, that I came across, was one of the four that I fitted to my Honda Shadow 700 V Twin. It ran two plugs per cylinder and one was not firing. I thought, at first, that I had an internal problem, but just to be on the safe side I replaced the suspect plug. Problem cure. They're the only plugs that I run on my supercharged B. However, when I purchased the supercharger kit from Moss, back in '02, it came with a set of cooler running Champion plugs. A short while after, Moss informed me that they were experiencing problems with the supplied Champion plugs and suggested a switch to NGK. RAY

Non Points Scott? Since when was an MGB running a 45D4 distributor a non points distributor
Again what is pushing it?

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LNDRVR4X4.COM
Home of Project "INCARN8'


1957 Series 1 Land Rover electric VEHICLE CONVERSION

FIXITUPCHAP.COM
FIXITUPCHAP INCORPORATED

RD3 Radar/ Electronic Warfare Technician
VIETNAM 1969-1972