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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Alan, <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Aside from the distributor bolt difference you note and perhaps the casting date, I have found no other differences in the 100 and A90 blocks. If fact the race motor in my 100 is an A90 block with all 100 internal parts and it works great.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Larry Paterson<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Healeys [mailto:healeys-bounces@autox.team.net] <b>On Behalf Of </b>Bluehealey<br><b>Sent:</b> Thursday, August 9, 2018 9:40 AM<br><b>To:</b> 'Austin Healey'<br><b>Subject:</b> [Healeys] AH100 v's A90 Engines.<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB>Team.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>I have both an AH100 and an A90 engine sat side by side on my garage floor. It is known that the AH100 was developed to take advantage of the A90 Atlantic mechanicals and therefore I assumed that the A90 and AH100 engines were essentially the same.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>When externally comparing these two engines there is a minor difference between them that surprises me. The AH100 distributor mounting base on the block has bolt holes tapped into bosses each side of the distributor hole. The A90 has a single boss and a single tapped hole.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>This indicates to me that the AH100 engine had its own block casting at the very least, and perhaps other variations too.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>Could someone advise if there any other significant differences between the AH100 and A90 engines?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>Many thanks.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB>AlanB<o:p></o:p></span></p></div></body></html>