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MG MGB Technical - Spark plugs

Hi,which spark plug specification would be recommended for a 846F engine? I have a 77 mgb USA model with a non original engine ie the 846F. I seem to recall the spark plug gap is less for engines pre 76 as opposed to engines after this year and with Stromburg carb. As written my engine is spec 846F (non-overdrive)with a Weber 32-36 electric choke.

Suggestions appreciated...
/Moss
Moss

NGK BP6ES - set to 25 thou for pre '75 and 35 thou after '75.

But you can set the gap at 25 thou on all engines - it reduces the peak voltage to 8 / 10 kilovolt which is all you really need and reduces the likelyhood of rotor arms, caps, leads breaking down.
Chris at Octarine Services

Hi Chris, thanks for your response. So the question is which year(s) is a 846F engine? Pre 75 or after. I know it gets complicated here as it depends on the market ie USA or UK. My engine 846F runs on a 45D dis. So I pressume it's UK spec. I'm also going to fit HIF4 SU carbs.

/Moss
Moss

846 is Sept '74 to Jun '76 ie the later spec.

846 is a UK spec engine, the 836/7, 798 & 801 engines were the north american equivalaents
Chris at Octarine Services

Hi Moss

NGK BP6ES or if lots of hot, hard driving NGK BP7ES. We usually gap to 35thou for naturally aspirated on leadfree fuels.

Peter
Peter Burgess Tuning

Thanks - know I know.
/Moss
Moss

This thread was discussed on 12/01/2014

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