<VV> Tune up questions

[Joel McGregor]

NGKs are great plugs.  The extended tip according to NGK is designed to run hotter at lower RPM and run at the rated temp at higher RPM.  They claim that the intake charge cools an extended tip plug more at higher RPM.  I read this 20+ years ago so I don't know where to reference.  It's supposed to allow running a cooler plug and still resist fouling.  How would an extended tip prevent water freezing?  Does ice have a lower resistance than water vapor?
Joel McGregor

-----Original Message-----
From: virtualvairs-bounces at corvair.org [mailto:virtualvairs-bounces at corvair.org] On Behalf Of Jim Davis
Subject: Re: <VV> Tune up questions

The extended tip spark plugs were an attempt to prevent "glazing".   
This is where the engine is cold soaked at temperatures below zero.  
When the engine fires for the first few times, the water from the combustion event tends to freeze on the porcelain tip, shorting out the plug; thus, the engine dies and won't restart.  Extending the tip warms up the plug faster and can help prevent the problem.  AC 44FFS were available for this problem.

I find the NGK has a better selection of heat ranges for Corvairs.  All my Corvairs have CR of 9.6 or higher thus need colder plugs than the 
standard 44FF.   NGK have BR5HS (same heat range as 44FF) as well as the 
BR6HS which is equivalent to the 42FF.   There is also a BR6HIX if you 
prefer a cold plug with an iridium tip.
Jim Davis