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MG MGA - Rich/Lean Spark plugs

Any feedback on fuel mixture. I removed these immediately after a fast run, with no idling. They are in order 1,2,3,4 from left to right.

The plugs are Autolite 63




Tysen McCarthy

I'd be happy with them but interested to hear what others think. I recently was shown plugs from a high performance engine after a run on the dyno at a expert engine builders shop. They where a little whiter than yours but expert said it is little difficult to read with modern unleaded fuels. He said to get a light and look deep into the cavity to see if insulator is clean at the base, don't worry about carbon build up on the inside of the threaded section.
Mike
Mike Ellsmore

Look good to me...
Gene Gillam

I'm a guts, I'd like them JUST a little darker specially no2
William Revit

I'm no expert but they look good to me.
Wirhout wishing to go off the thread, how long a run is required after adjusting to see the affect of any adjustment, and do the plugs need to be cleaned each time or do they "self clean".
Graham V

Very similar to the colour I have finally achieved after 20 years of trying with what I suspect were worn out jets in a new (reconditioned) set of carbs. I use Super unleaded 98 octane. New jets and needles got your colour at a stroke.

Steve
Steve Gyles

+1 on what Mike says. I had heard that it is difficult to get readings back when they started using ethanol laced fuel here in the states years ago.Don't know if that is what Tysen is using though.
gary starr

On our metho burning Chev racer a bit back we could never get a good plug reading mostly because of running it fairly rich at idle and low speed --you could go out and do a fair whack of laps and by the time it got back to the pits the plugs would be simply washed off clean and look brand new
The back of exhaust valves hold their colour well though, so by having a removable header pipe it's a simple job to remove the pipe and have a look at the back of an exhaust valve head---works for me
willy
William Revit

This thread was discussed between 05/09/2017 and 07/09/2017

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