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Porting 455 Heads


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I'm porting some '70 455 heads. There is a semicircular lump of material in each of the combustion chambers below the plugs. Does it have a purpose, or can it be removed? Seems to me it is just an obstruction to the flame front and a small hinderance to swirl. What say ye?

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It may add to the compression ratio. Any one figured out the cc's of it?<P>------------------<BR>George C. Thomas<BR>70 GS 455 12.teens<BR>86 GN Low 13's/ high 12's

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I can't find the specific information right now but I seem to remember it having something to do with keeping wet intake flow off the plug, (it helps break it up). Most porting jobs I have seem radius and smooth everything to avoid hot spots, including that lump. Another thing to check after you port the head is the spark plug threads where they enter the chamber. You don't want any exposed threads inside the chamber or they may actually glow red hot. They should be ground back if this is the case.<P>------------------<BR>Hal, btk@vbe.com

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