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MG MGA - Sparking plugs

I've got a set of N5C plugs in at the moment, but broke one today when trying to remove it. The only 'spare' I've got is an N9YC. Are they fully compatible?
Many thanks
Robert Sinclair

the 5 means it is a different heat range - it is a much colder plug that will probably foul fairly quickly in the MGA engine - why not just fit a new set of NGK BP6ES - much more reliable than Champion and cheap as chips. I can even get them in the local supermarket DIY section

http://www.briskusa.com/spark_plug_cross_reference_heat_range_chart



Dominic Clancy

Another vote for NGK. I wouldn't use anything else.
Dave O'Neill 2

My local tweaker, an Austin Healey man, discarded my Champions in favour of the NGKs and told me not to go back to them. They certainly run much better.
Shane
Shanerj

Only used NGK plugs for the last 20 years!

John
John Follett

NGK plugs are highly recommended. I don't use any other plugs.

Frank
F. Camilleri

Well that's pretty unanimous. I've just ordered a set of NGKs for delivery tomorrow. Thanks for your comments.
Robert Sinclair

Just bought a set at a silly price of £1.50 each!
Graeme Williams

$3-50 ea here
But on US ebay #2-50 for a set of 4 but ten million for postage
willy
William Revit

Plus import duty Willy!

Graeme Williams

I have just bought a set of BP6ES on ebay, also for only approx £1.50 each. My current plugs are BP7ES, from the chart I see that BP6ES are hotter, but what difference, if any, does that mean am I likely to see?
In particular, will I need to adjust the tuning?

I have just renewed the jet seals and always finding tuning a bit of a trial as I just cant seem to hear the difference when I lift the piston. I've tried colourtune, but dont seem able to see the colour change. So I set it up approximately, go for a 5 mile drive, look at the plugs and then adjust accordingly. Its a bit hit and miss, but seems to get there in the end.
My biggest bugbear is the filters. They are in the way so have to come off when adjusting the jet nuts, but if I test drive with them off, the "reading" is wrong as I believe the mixture will become richer when I put them on. And they have to come off to check the balancing afterwards too. Five minutes to do the tuning: half an hour minimum replacing the filters!

Graham
Graham V

Graham
Get one of the tiny, short reach, jet spanners and put it on your car key ring. You then don't need to remove the filters to adjust the jets.

Regards
Colin
Colin Manley

Colin
I have one of these (see picture) but still can't get to it with the filters on.
The air filter is in the way on the outside and the float bowl connection is on the inside. I guess I could take the springs off and attack it from the side but the rear Spring is always fiddly to replace in situ.
But following your post, I googled and see that many jet spanners are offset, is that what you have?
And you have made me think. I fancy making one that is vertically offset so it can approach from underneath. Onward and upward (pun not intended)
Graham



Graham V

Graham

I find the easiest way to balance the carbs is with the SU balancing rods. See here on my site: http://www.mgaroadster.co.uk/su_carburettor_tool.htm

I don't like removing the filters for balancing and tuning. In my opinion their absence give incorrect readings when put back on.

I remove the the springs when using the SU spanner. No issues.

Once I have tuned the carbs both for balance and plug colour I remove the piston housings and pistons to measure the depth of the jets below the bridge. I make a note then, if there is any significant difference between the two I equalise them then do a further tuneup.

Steve
Steve Gyles

Graham
You asked what difference the warmer plugs will make
They could possibly make cold starting better
During the warm up phase your engine should run smoother sooner compared to the colder plugs and it will be a tiddle more forgiving to little mixture discrepancies compared to the colder plugs and 'possibly' more economical
NGK plugs are fairly forgiving and overlap a bit more in their heat range than some other brands-6s should be a better choice
Robert
Champ N5 and N9y are basically interchangeable
N5 is colder
N9y is warmer BUT is projected tip which allows it to cool out better
N9y is used quite regularly as a better replacement for N5
GT Cortinas Jaguars etc that use N5 run better on N9y

willy
William Revit

Steve
Thanks for your input. Just come in from the garage and you are absolutely right of course. It's very straight forward to remove and replace both the springs for tuning, I have no idea why I had thought differently.
And being anxious to double check the balancing ASAP, your toolkit gave me Heath Robinson type inspiration. I inserted a large diameter drinking straw in each dashpot and it seems the two carbs are pushing up their pistons at a similar rate. I had balanced them when the filters were off, so was expecting it to be ok, but wanted to double check. Thank you.

Willy
Thanks for that explanation. So it seems I'm not going to notice a major change once its up and running.

Graham
Graham V

Graham

Glad it worked for you also. Your trick with the straws is one of many ways of doing it. The SU kit is quite useful though as it contains nice fitting tubes and wires. The tubes double up as a fuel level setting bar. And of course the spanner. Obtainable from the MGOC. I guess Burlens also do them but I have not checked.

After many years of trying I have finally got my mixture spot on. It has always been there and there abouts but never fully to my liking, always a bit on the rich side. The new jets and needles I installed a couple of months ago sorted it all out. The carbs I bought during the rebuild in 1997 were reconditioned exchange units from a reputable MGA supplier. I assumed the needles and jets were brand new and correct for the MGA. Now I am not so sure! How true is that old adage "don't assume, check". I have tried various needles during the years but never been happy. I now wonder whether the jets have been the cause of all the trouble and were worn. i.e. not replaced in the reconditioning process.

Steve
Steve Gyles

Graham
You probably will notice a difference -A new set of BP6's are always going to be better than 3 1/2 old Champs
willy
William Revit

Hi Willy
My current ones are NGK but BP7ES so one point down(up) the heat range.
Having said that, they are significantly more than 3.5 years old, although show no wear, as mileage is very low.
Graham
Graham V

Ahh yes
I forgot there for a sec that we have stolen Rob's Champion thread
6's will suit better than 7's as we discussed earlier
Cheers
willy
William Revit

This thread was discussed between 15/08/2017 and 05/09/2017

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