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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>Hi Ian,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks for responding. I am not going to another piston manufacturer; the older AE pistons are excellent quality and have a good reputation. You can’t judge the quality of castings and machining from an illustration, and half the time what is illustrated is not exactly what is sold anyhow. Omega pistons are also excellent and I have fitted them to classic BSA and Velocette motorcycles when I was doing a complete balance, Carrillo rods, bench flowing the head; the whole nine yards. However, with the Healey, unless you are building a performance engine, I do not see the need for forged pistons. That said, if I did not have the AE pistons, then I would have gone with the Omegas.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I would still like to hear about the purpose/wisdom behind the change in piston design that led to the introduction of the 5<sup>th</sup> ring. They would not have spent the extra money to switch up the machining if there was not a good reason.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='mso-fareast-language:EN-CA'>From:</span></b><span lang=EN-US style='mso-fareast-language:EN-CA'> Healeys <healeys-bounces@autox.team.net> <b>On Behalf Of </b>Ian Hey via Healeys<br><b>Sent:</b> April 16, 2021 2:09 PM<br><b>To:</b> healeys@autox.team.net<br><b>Subject:</b> [Healeys] To fit or not to fit<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB>In a recent engine rebuild of a standard BJ7 engine which was fitted with four ring pistons, when I looked at replacement pistons they were pictured with five rings, which did not seem good to me.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>I fitted Omega pistons from Denis Welch. These have three rings with a total width of 3.2mm compared with 9.8mm for the four rings. (For the oil rings only the width contacting the cylinder bore is measured)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Since friction is in proportion to ring width (possibly due to the lower pressure required to make thinner rings seat against the cylinder wall) this represents a reduction in losses to heat and a power increase (small).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Another, much more expensive, option for consideration. I also have no doubts about the quality of the pistons, whereas I am not sure about the four or five ringed replacements. They seem very cheap to me.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB>Ian<o:p></o:p></span></p></div></body></html>