Checking Spark Plugs for Mixture

steve livesley,
No1 front on the left

I had a good run in the MG during the week so thought a good time to check the plugs for colour which will give an indication of the fuel balance between the twin carbs.

There is quite a noticeable difference between the 2 front plugs and the 2 rear plugs. The rear 2 look very close to the best based on the plug colour chart whilst the 2 front plugs definitely look a bit lean.

Spark Plug Colour Chart

So a quarter turn on the front carb to richen the mixture slightly …… remember that with SU HIF carbs you screw in the mixture screw to enrichen it – not what you would expect.

See more about the spark plug colour guide at …… https://mgb.tips/2020/01/30/how-to-read-your-spark-plugs-2/

Visit …. The Green Spark Plug Company for a full selection of spark plugs and other servicing components.