Are these spark plugs too pale?

[Waynebaby]

Hi All,

Can someone with more experience and better colour vision than me tell me if they think these spark plugs are too pale? To my eyes I think they're indicating a weak fuel-air mixture but I'd appreciate a second opinion.

Cheers

Wayne

 

 

[dougbgt6]

Wayne! Yes!  Way to pale, you're running too weak. They should be biscuit colour, I also detect some pinkness? Do you use fuel additive? My plugs became so pink I couldn't tell white, biscuit or black!  Gave up on additive once I discovered the "memory of lead" theory. Plenty of threads on here about it.

Your plugs are bottom left I think?

http://www.classic-car-magazine.co.uk/articles/spark_plug_colour_guide_chart.html

[Waynebaby]

Thanks Doug,

You've confirmed my suspicions. As to a hint of pink I have to pass. I'm red-green colour-blind and so the concept of pink is a mystery to me! No fuel additive needed since I splashed out and got the head refurbished by Searles in 2015, although if my memory serves me I might well have used some for the octane boost when I couldn't get to a 99 octane pump.

The interesting thing is why the mixture is so weak. The only thing I've changed is to go from K&N pancake filters back to a standard filter set up and I'd assumed that if anything this switch would make the mixture richer. Perhaps the after-market set up isn't a free flowing as it's made out to be - I know that the car has run smoother and had a better tick over since the swap (and it's a lot quieter too).

I've enriched the mixture by a quarter of a turn (top adjustment on mine) and I'll take another look in a week to see what's changed.

Thanks for your help.

Wayne 

 

[dougbgt6]

My son-in-law is very colour blind, he can't tell which football team is which so he supports Newcastle United, purely on the basis that he's certain of black and white! 

Your timing may also be out, too far advanced?

 

[Waynebaby]

Hi Doug,

My commiserations regarding the news about your son-in-law.. 

I checked the timing today and it is a 10 degrees using the strobe gun, so I'm happy with that.

Wayne

 

[Pete Lewis]

I would be dubious about 3 electrode plugs with our simple Ht unless you have done some changes 

 

Whats the code on the plugs ????

Are the needles std spec or where they changed to suit the pancakes????

Are temperature compensators fitted on the carbs  ????

what breather sytem have you got  ?????

 

Pete

[Guest]

Wayne.

The other problem with 3x electrode plugs is that you cannot gap them properly as they wear, so it's a case of chucking them when they look to gappy. NGK plugs have a much better heat range tolerance so that would certainly be my choice of plug and run these on both of the classics. Fortunately they take the same plug - useful when buying a box of ten !!

As others have mentioned, attention to the other points such as timing, mixture, needles etc. also needs to be spot on; spark plugs are a very good indicator of issues, either singularly or combined.

Regards.

Richard.

 

 

[Waynebaby]

Hi Pete/Richard.

The plugs are NGK BP6ET (T for triple) but I've today swapped back to the standard BP6ES (S for single) and an annoying soft misfire across the rev range that I've been trying to eradicate for months has now vanished! The swap to triple electrode plugs was prompted by a comment from Nigel Clark in Practical Classics, where he contributes articles on his GT6 and Scimitar.

I'm not too sure about the needles. The PO claimed they'd been "fettled" but I have my doubts. The dreaded compensators are fitted (I haven't hardened down the screws) and the breather system is the pipe from the rocker box to the intake manifold.

Wayne

 

[Pete Lewis]

 its another case of upgrade is sometimes downwards

to get the idle mixture right you must get the Temp comps shut down and  2 new  o ring seals on their casing  

if  they suck  bypassed air past the throttle plates you cant get the idle mix  it right.

i should know your car by now but ''''''''..........£££%%%  senior moments prevale

     just to check what needles you should have ...pete

[Waynebaby]

Hi Pete,

I've a very late Mk. 3.

Wayne

[dougbgt6]

There are only two needles for mkk3 stroms, early and very late! So I doubt you have the wrong ones. Well, three, if you count the one for pancake air filters. 

10 degrees? well,  that would be too much for mine, even with the best of modern fuel. I'm around 7.

Teesside?  Is there  local team? 

[Waynebaby]

Doug,

Thanks for the suggestion about the timing. When I'm done with mixture twiddling I'll try retarding the timing and see how that goes.

The local team is Middlesbrough, but we try not to mention it too much!

Wayne

 

[Pete Lewis]

And hope you use engine oil in the dashpots

A thin oil wont give you richness for  any acceleration and you get a weak mixture over the range and flat spots

Pete

[Waynebaby]

I've got a little bottle of SU damper oil so I guess I'm using the right weight oil. No idea where it disappears to though - I seem to have to top them up every week!

[Pete Lewis]

Thats normally a straight 20 grade and shouls be ok

It gets lifted over the top of the shaft tube when the pistion drops quickly, and leaves through the two holes in the base of the air piston and gets burnt when mixed with the fueling.

Well it keeps it all well oiled   ha !

So all ok , someone hasnt removed the piston damper spring have they ?

Looks like you need to cork the TCs and richen the base mixture more

Pete