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MG MGB Technical - spark plugs, what's your choice?

I would like to know some of your opinions on brand and kind of sparkplugs you use in your mgb. I have not liked the platinum plugs, and kind of lean towards the bosch plug. what do you think.....Boyd
Boyd Peterson

We've used NGK BP6ES plugs on virtually everything, with nothing but success.

Sean
Sean Brown

I second the motion: NGK BP6ES. So what if they're Japanese? When's the last time you've seen a set of British Lodge spark plugs in this country?
Steve S.

To B honest I have never seen any difference in plugs. I use Champion. They were orginal equipment and work well. I have changed and use the small plugs now. RC12YC-RC9YC ETC. Bob Thompson/International Auto
Bob Thompson

Gotta be the NGK BP6ES - I won't fit the Champion plugs - even though I can get them cheaper.
Chris Betson

Tried em all, NGK BP6ES by far the best!
Robert Dougherty

NGK BP6ES...but I've used the Champion plugs before and they were fine. For some reason, I keep coming back to BP6ES (I wonder if it's sort of a "Pepsi" versus "Coke" kind of comparison).
Barry Kindig

Your right Coke's better!!
Bob Thompson

I use NGKs in all my cars, Switched over from Bosch Platinums which the PO had installed, runs better (changed plug wires, fuel and air filters at the same time,so not absolutely sure it was just the plugs but the car runs much better since.
Paul Tegler

I use NGK Iridium IX plugs they take less voltage to spark thus you get a hotter spark. They are pricey but they make your ingition system last longer well they claim that. They work great with my MSD ignition
Ross

NGK BP6ES! A good reliable standby. But NOT BP6ERS, the resistor version. I have not had all that good luck with ordinary Champions, but their copper cored version has seemed to give about the same results as the straight NGKs. For whatever reasons, Bosch's platinum plugs - both single and 4 electrode versions - seem to like to carbon foul, even tho the heat range given in the book indicates it should be as hot or hotter than the above NGKs.

One thing that could affect the results of any of these is the use of suppression wires with suppression type plugs. Too much suppression/resistance. The worst I have seen was a car with a suppression type rotor, wires and plugs. Made me wonder how much juice actually made it to the plugs! Not only is the plug type important, but so are these other factors/items.
Bob Muenchausen

I use the copper cored Champions, absolutley no problems and my old motor is using a pint of oil every 250 miles. They get black but they don't foul. Always starts with no trouble and runs well with no misfiring at all.
Paul Hollingworth

Back in my younger days, I tried NGK's in my Triumph 650 Bonniville and always had trouble with them fouling out. Went back to Champions and never looked back. JMHO, Bud
Bud G

Doubt there's much difference in plugs. Back when I earned a paycheck doing tune-ups, we found that Champions would sometimes break at the ceramic if you weren't careful installing (or removing) them.

Not such a big deal in an MGB, but in a mid-80's Buick with a transverse V-6, where you had to bend your arm in three places to get to the plugs in back...

Matt Kulka

I also add my vote for the NGK's. If anyone's interested, the stock number for the BP6ES plugs is 7333.

Alex
Alex

Any thing but champions. I have taken out champions with just a few 100 miles on them and replaced then with all but used up NGK's and recieved more performance and better MPG's
william harding

In 1969 I bought a new Lotus Elan S4SE.
In heavy traffic that car was a real pain, becoming more 'fussy' by the square of the time spent at 'tick over'.
A chum suggested NGK plugs and my problem was solved.
I have never used anything else since.

Today, the NGK BP6ES would be the ideal plug for your car.
AJ Munro

Some cars are rather finicky.

My '77 roadster loved his Bosch Platinums, anything else fouled easily. Burned a bit of oil as well, but with the Bosch they never fouled.

My '69 likes the NGKs and not the pricey Bosch, go figure?

Luis
Luis

I use the NGKs, but have tried nothing else except for the Bosch ones that were in the car when I got it. Anyway, I'd always used the non-resistor version up until now. The last time I went to the parts store, I got the resistor version even though I asked for the others(I didn't notice until I got home.) I threw them in anyway and haven't noticed any difference.

I know a guy that works for an auto parts distributor, so I asked him about it. He said most manufacturers are going to this type of plug and that performance wise they are no different. In fact, he says that in Canada all plugs by law have to be resistor-type, even in a lawn mower! What gives, is this true? I'd be interested in hearing more about this, especially from Ross or other neighbors in the Great White North.
Jared Snider

Like Jared, I went to the local Bumper to Bumper to pick up some NGK BP6ES. The guy had to get them from the warehouse. I picked them up the next day, and he told me that the plug number had changed. I didn't bother to look at the box till much later and discovered that they were actually BP6ERS. So you might be right about not being able to get the non-resistors in Canada. I'll have to check next time I'm at the parts store. I haven't really noticed any differences between the Champions, NGK or Bosch, however I lean towards the NGK. However, the British mechanic who was going to put my car on the dyno yanked them out and installed some regular non-resistor Bosch plugs, insisting that they were much better. The only real way to tell is on the dyno, and based on numerous MGA's, MGB's, Triumphs, and Jags that they've run on their dyno, the local British place recommends the Bosch. So who knows...
SteveO

OK, it looks like the NGKs win out. Now, what's the proper gap for these plugs? I have a '64 with the original 3 main engine.

Thanks,
Rich
Rich F.

That is somewhat dependant on what you have for an ignition setup.
For stock .025 on up to .035, and up from there depending on your particular setup.
I have a mostly stock 25D and stock coil and am running .035 with no problems.
Points and timing are very stable.
.

Thanks ., .

I have a completely stock setup, so I'll go with 0.035

Rich
Rich F.

The normal recommendation for your engine is 25 thou not 35 which was the setting for the later 18V engines using the 45D dizzy.

I think the wider gap and hence higher Kv is required to burn the leaner mixture of the later engine. The early engine runs richer and the smaller gap produces lower peak Kv and a more stable spark.
Chris Betson

I've replaced my stock coil with the Lucas sport coil. Reset the plug gap to .030. Is that sufficient or should I take to .035? Any thoughts?

Thanks

Bob
Bob Roberts

Bob,

.030 will fire fine, but you may have accelerated points wear. The larger spark plug gap gives a bigger spark, which theoretically translates to slightly better combustion. I have not seen any dyno testing figures regarding spark plug gap, so what you run is up to you. Of course if you have converted to or already had electronic ignition, the points wear is not a consideration and you can go up to .035 w/no problem. I have run .035 with the sports coil and points, and it was not a problem at all.
Paul Konkle

Just to be different, I use NGK BP7EV. They are expensive (you have to get them from a motorcycle shop) but seemed to cure some of my running-on problems. Easy to foul if the mixture goes rich, and amost impossible to clean.

Champion is the cheapest, but you get what you pay for. I wouldn't touch them personally.

Neil
Neil

Neil,
You should be able to get BP7ES at any parts store. They are a heat range colder which probably has more to due with the run-on and ease of fouling than the plugs being the EVs.
Leland Bradley

BP6ES has been my favorite for standard and mildly modified engines. Other tunes may have different specs depending on the loads they are being put too - usually circuit racing, then BP7ES is the better choice for most specs, but 8's are neded sometimes. Engines glaze these colder running plugs when not used hard which is why Neil has those conditions.

My preference dates back to times, now passed, when NGK could give a measurable power advantage, or more accurately other plugs, and notably Champion, lost power. Bosch incidentally were always closest to NGK. A classic example was with the first Twin Cam 16 valve MGB I built over a decade ago, when this was being set up on the rolling road. A change from new Champions to new NGK of the same heat range saw a 18 bhp increase at peak power. Subsequent fitting of another new set of Champions saw the power drop by 16 bhp. This test was repeated at a later date with a standard Rover 820 from which the engine came from and a much smaller but equally useful power gain was seen. In the mid 1990's a repeat test using a number ofg other makes of plug saw a range of about 4 bhp top to bottom. The others had caught up however the NGK was still at the top.

The other point of note is one of 'fatter sparks'. When you put an engine under full load at all rpms and monitor what is happening it provides a very clear picture to potential problems. One viewed aspect is the firing voltages. This is the voltage peaks in the ignition that are seen before the spark jumps the gap. Under full load with high cylinder pressures the voltages are higher. However a good clean system sees the firing voltages running at between 11 and 15Kv. Introduce worn plugs that have eroded edges to the electrodes and the firing voltages often soar to well over 20 and sometimes over 25Kv.

If your system is capable of only delivering 25Kv at best, then it follows that if the plugs need over 25Kv to see a spark, then the engine misfires. This is when having a system with a greater reserve comes in handy. However you then fit new plugs and drop the firing voltages to reasonable levels. If you have a greater reserve of HT delivery voltage, say 40Kv from a sports coil then this isn't going to do anything if you run standard plug gaps as it stil only needs the same voltage before the spark jumps and discharges the coil. Opening up the plug gap means that the voltage has to rise before the spark jumps and this is where you gain from a 'fatter spark'.

However, and there is always one or two of these, pushing up the base line firing voltage eats into the reserve and you have to be careful to leave enough room for adverse conditions. This isn't just the coil output, but of far more dignificance is the actual performance of the other HT carrying components in the HT system. If these remain standard then yoiu realy run the risk of damp weather finding all the current going straight to earth and no working engine until you narrow the gaps. So if you are thjinking of taking advanatge of a high outpur coil and opening up plug gaps do remember to uprate, or keep routinely renewing other HT parts.

Rog
Roger Parker

In our air cooled engine shop, we buy plugs in case lots of 200 plugs. With Champion about 190-195 of the plugs will fire when new. NO other brand we have found will come close to that. We have tryed Bosch,NGK,AC and Splitfire and these brands usually product 175-180 good plugs per case. The warranty on all of them is good and they will be replaced, but why mess with bad-new plugs.
Jimmy Chew

This thread was discussed between 09/03/2002 and 17/03/2002

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