Lotus Elan

NGK plugs

PostPost by: Geoffers71 » Fri Nov 23, 2018 8:18 pm

I've been having a Dickens of a job starting my S2 lately. I've fitted an electric pump for priming purposes only, so I know that the carbs have the right level of fuel (41mm from top of carb body) and the electrical side, timing and ignition, was fine with almost new NGK BP R6ES plugs (well maybe they'd done 500 miles or so. But over time it was becoming increasingly difficult to start from cold. After cranking for what seemed ages it would try to fire and maybe eventually it would start, poorly to begin with and then it would clear and run quite smoothly. This morning it flatly refused to start at all. I checked everything again and saw that the plugs were wet and black. I gave up and put the battery on charge as it was almost flat. This afternoon I had a thought and swapped the plugs for an older set of NGK BP6ES and the engine started immediately and ran smoothly from the start.
Not withstanding faulty plugs, My question is would the Resistance plugs BPR6ES be the problem rather than the BP6ES? I think the R plugs are to mask issues of radio, Ecu etc interference and that is not an issue with the Elan, but would they foul up more quickly than the standard ones? First time I've used the R plugs and Never had any issues with plugs before
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PostPost by: richardcox_lotus » Fri Nov 23, 2018 8:39 pm

I?ve used the R plugs over the last decade or so and never had an issue. Beware counterfeits from EBay though !

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PostPost by: Spyder fan » Fri Nov 23, 2018 8:39 pm

Geoff,
Are you starting the car from cold and using it on the road for a good run or just moving the car in and out of the garage?

If it?s out on the road for a good run, then the plugs may be at fault, but if just starting and moving the car even if you let it warm up properly before putting it away then the plugs will irreversibly foul and give the symptoms you describe.

How do I know? Been there done that when I still ran an LTC and so has Vince Reynard on here. New plugs always solved the issue and the old ones were scrap no matter how carefully you cleaned them

This website gives some insight as to why this happens https://www.gsparkplug.com/shop/fouling ... on-vs-ngk/
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PostPost by: promotor » Fri Nov 23, 2018 9:38 pm

richardcox_lotus wrote:I?ve used the R plugs over the last decade or so and never had an issue. Beware counterfeits from EBay though !

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Richard


This was my thought also. I had a set of NGK BPR6ES and the metal crush-gasket fell off after only tightening and loosening one of the plugs just once. The brand name printing of NGK on them looked poor which also suggested they were counterfeit.
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PostPost by: p.faurie » Fri Nov 23, 2018 10:34 pm

I believe I had the same problem,bought a set of "ngk"plugs off the internet had miss firing problems and very poor cold start,put the old set back in runs and starts fine,visually the only difference I could see was the new ones were gold colour,the old ones are silver(the metal part) I didn't think they were fake just faulty,but you never know nowadays.
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PostPost by: 69S4 » Fri Nov 23, 2018 11:06 pm

What plug leads are you using? If you?re using leads with their own resistance ?built in? with a set of resistance plugs you?ll be getting a very weak spark.
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PostPost by: Geoffers71 » Sat Nov 24, 2018 8:24 am

Thanks for all of the replies chaps, very informative.
Alan, you may have put your finger on the problem. I haven't used the car on the road for a bit, but have been starting her up, eventually :roll: , and letting her warm up a bit then tucking her up again for a few weeks. As you say that would cause the plugs to foul up irretrievably. So, maybe the R plugs aren't an issue per se, just the way I've used the car. Anyway, problem solved.
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PostPost by: William2 » Sat Nov 24, 2018 5:07 pm

I have always gone down the route of BP6ES plugs with seperate NGK resistor plug caps. Having said that I still use copper core leads with my Powerspark electronic ignition module. Never had any problems. I also fitted a rubber primer bulb like others have and 2 years on it still works a treat for priming the carbs. IMO one of the best, simplest and cheapest mods you can fit to an Elan.
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PostPost by: englishmaninwales » Sat Nov 24, 2018 8:01 pm

What voltage are you seeing when cranking?
If the battery is not in tip top charge condition (for example my radio has a small charge drain if I?ve forgotten the isolator), I find my engine is difficult to start when cold. Same plugs as you.

I get then an immediate start with a battery booster pack.

Just my tuppence worth!
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PostPost by: RichardHawkins » Sat Nov 24, 2018 8:29 pm

Gentlemen,

I read a monthly mag called Practical Performance Car.

One of the contributors is Dave Walker of Emerald. Dave runs a rolling road tuning company and has been doing this sort of work for a long time, he always has something useful to say. With respect to spark plugs Dave says, they never recover from being fouled or wet. He fits the cheapest plugs until he has set the ignition and fuel nearly correct, then uses the correct plug which he is no longer in danger of fouling.

He does not give an explanation, but his advice certainly agrees with that given above.

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PostPost by: alanr » Sun Nov 25, 2018 9:39 am

Ok so what I have learnt from this thread is that the spark plugs that we are buying today are of lower quality than they were back 40years ago and not really of suitable quality for older carburettor type engines.
If this is actual fact surely NGK/Champion/Bosch etc would know this and would produce a suitable spark plug appropriate for the issue with older cars and modern fuel?....Or do they and maybe we haven't yet tracked them down?
Most on here seems to favour NGK plugs, but it would be good to hear from someone who is using Bosch, Champion, or another make spark plug with success in the twink.
Last edited by alanr on Sun Nov 25, 2018 11:21 am, edited 1 time in total.
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PostPost by: richardcox_lotus » Sun Nov 25, 2018 10:35 am

Well Alan I wouldn?t say they are of lower quality. The inference I get is that if plugs are flooded they ?may? not recover.

FYI I?ve had my Elan for nearly 25 years - the only plug fouling issues I?ve had were with Champions...

My 3 year old NGKs are fine.

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PostPost by: alanr » Sun Nov 25, 2018 11:31 am

What is alien to me is the comment that a flooded spark plug may not be recoverable!
With 50years of motor trade experience I have never come across this before. Yes a faulty plug does happen maybe, but in general terms a flooded plug in my experience can be cleaned and reused.
So what we are now saying is that the newer type spark plugs, predominately made for injection engines and modern fuel, are none cleanable (sandblasted) and are scrap if 'flooded'? :(
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PostPost by: Elan45 » Sun Nov 25, 2018 6:54 pm

My S3 SS was fitted w/ Bosch plugs when I bought it in 1974. In 1976 I replaced them w/ NGK BP 7 ES. I've run this heat range ever since and also use the 8 and 9 heat range in the race cars, but always 7 in the street Elans. I don't have a NGK book here in FL, but 7 was the range the book quoted in the 70's. I'd be concerned that 6 is too hot.

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PostPost by: Matt Elan » Sun Nov 25, 2018 7:02 pm

When I ran some hot British bikes a few years ago the issue of fake spark plugs was fairly common, so I never buy them from the internet. The second issue is that modern plugs, I believe, only the tip of the ceramic insulator glazed, while earlier plugs had much more if not all of it glazed. So the modern plugs are more prone to fouling due to build ups of residue on the insulator.
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