plug fouling

[Richard Fridd]

i am currently experiencing plug fouling after around 100 miles of driving.[BP7ES plugs/1.3 standard engine]there are mild carbon deposits on the electrode+fuel wetting.i suspected over rich mixture causing initial fouling leading to poor spark hence fuel not burning.normally cleaning the plugs would cure the problem until carbon builds up again.but not in this case.only renewing all 4 plugs solves the problem for another 100 miles of apparently normal performance/good starting etc.which suggests fuelling+ignition functioning correctly.before i start investigating further if anyone has experienced similar i would be most grateful for advice.perhaps my car is hinting that i should treat it to those new old stock dellorto 35s being offered @ £££1199 on the lacisti community website! do these fit the solex inlet manifold?best regards richard

[Sliding Pillar]

I always used NGK BP6ES plugs in a 1300 Fulvia.

[fay66]

i am currently experiencing plug fouling after around 100 miles of driving.[BP7ES plugs/1.3 standard engine]there are mild carbon deposits on the electrode+fuel wetting.i suspected over rich mixture causing initial fouling leading to poor spark hence fuel not burning.normally cleaning the plugs would cure the problem until carbon builds up again.but not in this case.only renewing all 4 plugs solves the problem for another 100 miles of apparently normal performance/good starting etc.which suggests fuelling+ignition functioning correctly.before i start investigating further if anyone has experienced similar i would be most grateful for advice.perhaps my car is hinting that i should treat it to those new old stock dellorto 35s being offered @ £££1199 on the lacisti community website! do these fit the solex inlet manifold?best regards richard

Hi Richard,
I've just changed my plugs today as starting wasn't as good as it normally is, and I was getting a misfire for about 100yds before the plug cleared and she ran smooth, No 1 plug seemed to be the culprit as the gap had opened up quite a bit, although the other 3 were ok.
But I did notice they were sooted up a bit.
As for the Dellortos, I changed from Solex 32's to a pair of new Dellorto 32 DHLb's about 7 years ago and it was a real good move,  my 2c (1091cc) runs much better and stays in tune far longer than I thought they would, so i'd recommend them to anyone, but, and it is a big but, I paid considerably less than your £1199 for mine.
Bria
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[Richard Fridd]

can anyone tell me the difference between BP6ES and BP7ES?is there a big difference?richard

[chrislg]

The BP6ES plug is a slightly hotter running plug, so as long as the fuel mixture is not too weak should be okay for Fulvias, like Ade I also used the BP6ES on the recommendation of Harry Manning when I suffered problems with Champion plugs fouling.

One thing that also may cause a problem is the quality of fuel. Some in the USA have repoted problems with plugs when using fuel with methonal added. I would also stay clear of most supermarket fuel which has always given me problems, the exception is possibly the Tesco 99 octane fuel.

Chris

[lancialulu]

Re BP6ES the Fulvia Q&A on vivalancia.com says that 6's should be used if soot fouling occurs with 7's on all non 1600 fulvias. Having said that my 1.3S runs fine on 7's. Like Chris I have tried champion eqivelent and they foul!. I always try to use Shell Optimax....plus Castrol valve master plus

I have 35 dellortos on my 1600 sport and while they "throttle the top speed" as the venturi size is too small for 5500 rpm plus on a 1600 they do stay in tune, tick over very smoothly, and provide 30% better fuel economy. However I dont think you would see these benfits so much on a 1300 unless your solex's are shagged. I certainly would not pay 1200 quid. although they will fit your manifold!!!!

Tim

[Richard Fridd]

i do use tesco 99 fuel only,which did seem to give enhanced performance when thrust 4 star became unavailable locally

[roddy]

Hello Richard

Just as I use the platinum tipped NGK V tip plugs in my 1600 engines, I would suggest that you change to the equivalent modern iridium tipped plug for the 1300 - NGK BPR 7EIX.   I got a set of 4 recently from Ace Parts in Alderney, C.I. for £27.25 (an eBay shop and PayPal).   NGK plugs seem to have a wider tolerance of temperatures, than some others.   Also, the converse of Champion, the lower the number, the hotter the plug and the risk of detonation if the mixture is too weak.

Don't get me started on the quality of fuels and bio contents!.......   (However I am very pleased with Tesco 99 octane)

Regards - Roddy

[fay66]

Hello Richard

Just as I use the platinum tipped NGK V tip plugs in my 1600 engines, I would suggest that you change to the equivalent modern iridium tipped plug for the 1300 - NGK BPR 7EIX.   I got a set of 4 recently from Ace Parts in Alderney, C.I. for £27.25 (an eBay shop and PayPal).   NGK plugs seem to have a wider tolerance of temperatures, than some others.   Also, the converse of Champion, the lower the number, the hotter the plug and the risk of detonation if the mixture is too weak.

Don't get me started on the quality of fuels and bio contents!.......   (However I am very pleased with Tesco 99 octane)

Regards - Roddy

All the answers so far have been relevant to 1300cc engines.
In my case I'm using NGKBPR7ES in my 1091cc 2c, what would be my best choice to overcome fouling as she always seem to be on the rich side. would I benefit from NGK BP6ES or would the NGK BPR 7EIX  be a better choice, and what are the benefits, even though they are considerably more expensive.

Brian
8227

[lancialulu]

Brian

The vivalancia faq on this recommends a B6ES (no "P"!) which will be a hotter plug that a 7. Not sure what P stands for but someone (you?) can find out from NGK interweb stuff.

Tim

Also I think (not wishing to upset) but Roddy may have got it the wrong way round re Champion - they are opposite to NGK in numbering but up the numbers for a hotter plug unlike NGK which lowers them. I got this from a champion site:

Say you are starting with a RCJ7Y
if you want a colder plug, you would use RCJ6Y
if you want a hotter plug, you would use RCJ8Y

[fay66]

Brian

The vivalancia faq on this recommends a B6ES (no "P"!) which will be a hotter plug that a 7. Not sure what P stands for but someone (you?) can find out from NGK interweb stuff.

Tim

Also I think (not wishing to upset) but Roddy may have got it the wrong way round re Champion - they are opposite to NGK in numbering but up the numbers for a hotter plug unlike NGK which lowers them. I got this from a champion site:

Say you are starting with a RCJ7Y
if you want a colder plug, you would use RCJ6Y
if you want a hotter plug, you would use RCJ8Y

Thanks tim,
I'll try and find out what the P means, however these came from Omicron, as have all previous plugs fitted, so I hope they are OK.!

Brian
8227
P means projected insulator & the R is for Resistor, see http://www.mirage-performance.com/tech/sparkplugs.html
So it looks like I need 6's
Brian
8227

[johnturner]

This sounds horribly familiar..The Lambda is wonderfully insensitive to plugs and for years was happy with anything i could find rattling around in the bottom of the kitchen drawer, but about ten years ago it began to develop a persistent misfire with the plugs sooting up.  After replacing the jets, then carburettor, petrol feed, plugs, leads, magneto and so on I was about to push the car into the nearest ditch when a biker friend pointed out that his Triumphs had bregun to suffer exactly the same problem.  It now seems certain that the cause is the change in the specification of fuels around the time of the switch to unleaded.  I talked to a bloke at Shell who explained that fuels are now designed for fuel injection and don't neccessarily vapourise properly in a carburettor and suggested that raising the running temperature to at least 80c would help. Fitting thermostats, blanking the radiator and getting some heat from the exhaust into the inlet tract seems to have solved the problem though it still recurs periodically. The Fulvia problem may be entirely different but I would avoid using a weaker mixture because of the risk of burning expensive bits. Different makes if not grades of plugs seem to behave differently as do different carburettors: those running Lambdas on an SU don't seem to suffer so badly as those running on the original Zenith.

[fay66]

Thank you John,
There's nothing New in the World!
I think I'll try using a hotter plug and see if that makes a difference..

Brian
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