>Be all that as it may... I also have a dieseling problem. I don't know if
>it is plug related or not, but I'm interested in trying a cooler plug to see
>if that will help. I assume that's the direction I want to go in? What is
>the secret to knowing what plug is one or two steps cooler than the N9Y?
Plug temp refers to the RATE at which the plugs dissipates heat from the
center electrode back thru the thread and into the block. Installing a
plug that is a heat range or two higher than recommended is the same as
installing a glow plug.
>What other implications are there in switching to a cooler plug?
NONE, it does not affect the spark in any way.
Carbon build up was also mentioned as a possible problem for dieseling.
Unless you are burning a huge amount of oil, carbon does not build up in
a sufficient amount to cause dieseling. You need a hunk of carbon that
is large enough to hold and give off enough heat to cause ignition of the
air/fuel mixture.
Personal case: When I first bought my 73B it was running N9Ys. I changed
them out for another pair during an initial tune up. I was having
dieseling problems. I put AC Delcos in and guess what... no dieseling.
Upon rebuild I found that there was a bit of carbon build up, (1/4"), on
all of the valve flats. Plugs DO make a big difference.
John Knight
'73 MGB (undergoing restoration)
"If uniqueness makes us who we are... why be like everyone else?"
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