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<DIV>According to Bob Kirkman's Corvair cylinder head chart in the
Tech Guide, <BR>Corvair heads for each hp were made for 1962--64 that had
two different size <BR>holes drilled in the right hand side of the head
looking at the rocker box. <BR>Some heads had two 1/4-20 holes and others
had two 5/16-18 holes. (not the <BR>3/8-16 holes!)<BR><BR>I know why this
might be for the 140 hp engines because of the LH muffler, <BR>but I'm
talking about the EMs (esp 1964s).<BR><BR>Does anyone know why there were two
different heads of each hp with <BR>different hole sizes? I
understand the purpose of having holes there. Just why two <BR>different
sizes?<BR><BR>Thanks in advance.<BR>Regards,<BR>Bob Helt
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