Graduations in NGK sparkplugs

[MikeNash]

I want to find a cooler running plug than the BP6ES that I'm currently using but my locals motor shops don't give much confidence on their understanding of the above. What would be the next two steps up?
The background is that till now BP6ES has been fine but recently when charging up the M3 hill south past Basingstoke at 65mph on a hot day I had a horrible attack of pre-ignition. I'm working on the old maxim of "Use the hardest plug that won't oil up".
Regards, Mike N.

[Cam]

Right well the next one up is the BP7ES and the one after that (go on, guess ) is the BP8ES.

I am using the BP8ES plugs and find them to be excellent. Most motorfactors can order them for you if they can be bothered but you might have to buy a box. I think the MG centre in Birmingham (next door to the Birmingham Moggy centre) do them. I bought some off them a couple of years ago...

I'm assuming that you have a tuned engine with high compression though as with a standard Minor engine you will not need them. You need to check your fuelling and ignition timing if you are running a standard 1098.

[MikeNash]

Thanks, Mr Cam! Thought so, but when you get a response of "..errr, I fink its it the 7 ..err no, err yeh, its the 7" you don't bet your engine on it. My engine's standard, (at least I think so) and yes I'm doing the checks. Its just that occasionally it has to be driven hard and at the moment its flying. The engine's due for overhaul (heads' not been off for 37 years) but it won't die! But flat out up hill brings the pains on.
Taa! Mike N.

[Kevin]

If you need to get futher clarification try
http://www.ngkntk.co.uk

[Cam]

Thanks, Mr Cam! Thought so, but when you get a response of "..errr, I fink its it the 7 ..err no, err yeh, its the 7" you don't bet your engine on it.

Yes mate I know what you mean, I've been there quite a few times myself!

My engine's standard, (at least I think so) and yes I'm doing the checks. Its just that occasionally it has to be driven hard and at the moment its flying. The engine's due for overhaul (heads' not been off for 37 years) but it won't die! But flat out up hill brings the pains on.
Taa! Mike N.

Well the head might be in need of a decoke, but check your ignition timing and maybe knock it back a couple of degrees and see if the pinking reduces/disappears. I honestly don't think that changing to a colder plug will be the way forward personally if the engine is pretty standard and running standard compression. You might find it's more difficult to start too.

[MikeNash]

Got no pinking - a dfferent and distinct "pip" noise, instant cut out on one or two cylinders and rapid water temperature rise, all in the middle lane where you can't just stop! Pulled over, reduced throttle and slowed down, pulled out the choke to cool off and brought it under control and then preceded a bit slower. I'll decoke when I get the chance and in the meantime go up a grade - still believe in "As hard a plug as you can without oiling up". Anyway I'll let you know how it goes. Regards, Mike N.

[Cam]

still believe in "As hard a plug as you can without oiling up".

Oh yes, me too, but if it's a standard A-series then it should behave like all the others unless it has a fault. In which case the fault needs sorting out and perhaps not masking.

But whatever you decide to do, let us know how you get on.

[MikeNash]

Found the fault. Didn't have time to do a strobe test after a rapid clean and gapping of the igntion points and although done with care, wound up with a static advance of 10 degrees! Corrected later, but in going up the same hill at Basinstoke at 60 mph listened carefully and just caught it as misfire started. Probably cooked the plugs in the earlier pre-ignition. So now fitted NGK BP7ES and I'll see how we go. Looking forward to the next jam and slow crawl on the M3!
MikeN.