From: daveph @ ix.netcom.com (David Hay) @ USDESMTP
Date: 08/20/96 05:56:14 PM
Subject: spark plugs and carbon
<Greetings all!
<
<Got the MGB out of mothballs and on the road for the first time since
<1990. Been driving it for 3 weeks and am still getting the small bugs
<out. I have a few simple question I thought someone might know
<something about:
<
<1. What is a "cold" spark plug that can be used in the MGB? Also, what
<is a "hot" plug (don't say it's just the opposite please ;)) and where
<does the Champion N-9Y fall in this temperature range?
<
<2. Is there an easy way of decarbonizing the combustion chambers
<without taking off the head? I'm experiencing nasty dieseling and it's
<not related to timing. Had a carb mixture problem that I've recently
<fixed.
<
<Hope this stuff hasn't just been covered since I've been off the list
<for the last 2 weeks and not even realized it (been kinda busy catching
<up with an old friend). Thanks always.
<
<Dave Hay
What I have heard:
People used to decarbonize in the old days, but nowadays
you're just supposed to switch to a higher octane and leave the
carbon alone. The theory is the carbon uses up some of the
volume of the combustion chamber. This increases the compression
ratio, thus the need for higher octane. Supposedly the carbon
can only reach a certain thickness, after which it falls off.
Anyway, this is what I have heard.
My TD is loaded with carbon, but is running fine on premium
gas. Anybody out there heard of someone pulling the head for
the sole purpose of removing the carbon? Will excess carbon
eventually burn off, once the the air/fuel mixture is properly set?
Bob Donahue, Still Stuck in the '50s
53 MG-TD, under DIY restoration
71 MGB, still in shop, 10 months and counting
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