Sooty Plugs

[riverstar]

Once warmed up my 4A drives really well, I do need to play with the choke for the first mile or so from cold but after that no problem however my plugs are always sooty.

 

I am running on a pair of Stromberg 175 CD2 which were professionally refurbished a few years ago and despite balancing and adjusting according to the manual a number of times I am still getting sooty plugs. I did try using a colourtune kit but couldn’t detect any colour change when adjusting.

 

As the car is working so well one half of me is tempted to leave alone but the other half wants to get it right.

 

Any suggestions most welcome.

[Lebro]

Sounds to me like the wrong needles may be fitted.

Sooty plugs means too rich when driving at normal speeds, but your use of choke for the first mile or two suggests that at lower revs / throttle opening the mixture is about right.

 

Bob.

[ChrisR-4A]

Hi riv, try doing a plug chop, run car on road until well warmed up and then go down local byepass at about 60/65 for a mile or two then cut the ignition at 60 and cruise to a halt in a suitable layby.

If plugs are fine then start her up let tickover for half a min and recheck plugs if still ok then i would leave as is. If however the plugs are then black i would check the choke bar is turning fully off and if ok then check the float levels and floats for any holes or fuel inside. Wrong needles is a possobility as is badly centred piston and diaphram, make shure piston drops feely to the bridge when lifted about 10 mm with a screwdriver.

Regards Chris

Edited October 18, 2014 by potts4a

[riverstar]

I have just checked the needles and I have 2A fitted are these the best option or should I try a different needle?