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From: tmorris@convex.UUCP
Newsgroups: net.auto.tech
Subject: Re: Spark Plug Deposits
Message-ID: <94400002@convex>
Date: Mon, 25-Nov-85 09:55:00 EST
Article-I.D.: convex.94400002
Posted: Mon Nov 25 09:55:00 1985
Date-Received: Thu, 28-Nov-85 03:14:46 EST
References: <633@bonnie.UUCP>
Lines: 21
Nf-ID: #R:bonnie.UUCP:633:convex:94400002:000:1336
Nf-From: convex.UUCP!tmorris    Nov 25 08:55:00 1985


	Which two plugs were they ?  Cyls. 7&8 often do this on small blocks
when the valve guide oil seals go out . Due to the tilt of the engine in the 
chassis (about 7 degrees in most vehicles ) , the oil in the valve covers
has to run past the valve guides to get to the drain hole to the crankcase .
If the valve guide seals are gone (they usually crack and break off ),then
oil can be drawn in on the intake stroke and burned .
	Due to the path it takes in the combustion chamber (ie in with the
fuel , across the plug gap due to swirl ) it tends to build up on the plug.
Why is it white instead of black ? Because it is a very small amount of oil ,
and it is being concentrated on the hottest part of the combustion chamber .
The result is not oil residue per se , but the ash left from burning the oil
 ADDITIVES at high temperatures .
	Another unpleasant result is pinging when the engine gets hot , as the 
deposits retain enough heat to pre-ignite the mixture before the spark is 
applied . The deposits also form on the faces of the valves , and are most 
resistant to any combustion chamber cleaner . Head removal is usually the
only method of cleaning at the advanced stage .Prior to that , try changing the
guide seals (can be done without removing the heads) and a fresh set of plugs.

					tmorris@convex ,disclaim,disclaim!