<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Actually I mis-spoke below…<div class=""><br class=""></div><div class="">A longer rod would make the piston come up higher, but it would also start higher, not lower as I wrote.</div><div class=""><br class=""></div><div class="">Roger<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Apr 6, 2020, at 1:39 PM, Roger Moffat <<a href="mailto:rogerkiwi@gmail.com" class="">rogerkiwi@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div class=""><br class=""><blockquote type="cite" class=""><div class="">On Apr 6, 2020, at 11:35 AM, Dave Maynard <<a href="mailto:dave@themaplehillfarm.com" class="">dave@themaplehillfarm.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="caret-color: rgb(0, 0, 0); font-family: LucidaGrande; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class=""><span class="Apple-converted-space"> </span> My friend and mechanic help has a Jacobson mower he's is rebuilding that has a 4 cylinder version of this motor that appears identical except the number of cyl's. He found the rod to be the same except it a tweak shorter by an almost immeasurable amount, maybe .005 or .010. Part number is almost the same except last digit and now I'm wondering if that could be someone's mistake. Would shorter rod cause preignition?</span></div></blockquote></div><br class=""><div class="">No, a longer rod would cause that - the piston is coming up higher in the cylinder (and starting fractionally lower) so there’s greater compression in a cylinder with a longer rod (or a piston with a higher deck height).</div><div class=""><br class=""></div><div class="">Roger</div></div></div></blockquote></div><br class=""></div></body></html>