<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Dave, </div><div><br></div><div>I chased this longer than I’d like to admit. The TR3 acted, to me, like it wanted more fuel so I always kept trying to solve a lean condition or a fuel starvation issue. </div><div><br></div><div>I finally broke down and installed an O2 sensor and AFR gauge, like you have. Guess what, I had too much fuel. At the time using RC needles in HS6 SUs with air horns and no filter. Engine is 87mm 12.5:1 with a 298 cam. </div><div><br></div><div>Sorry don’t recall the needles I swapped to but they were slightly leaner and motor no longer stumbles at 5500. In fact it came alive.</div><div><br></div><div>Your AFR of 10.5 sounds a bit rich to me. </div><div><br></div><div>That said, falling flat at half throttle under load sounds like something else. </div><div><br></div><br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Sent from my iPhone</div><div dir="ltr"><br><blockquote type="cite">On May 16, 2024, at 17:57, Mike Harmuth via Fot <fot@autox.team.net> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">Dave, here's a link to an online SU needle comparison program. Select your carb size and then add needles from the pull down to compare them. The RC and RA have different curves but end up in about the same place.<div><br></div><div> How's your timing? Is the advance working? Check your throttle linkage, are you getting the butterflies fully open? <div>Compression check out OK? Do you have another set of plugs? Did you re-check rocker clearance? Cam timing off?<br><div><br><div><a href="http://www.mintylamb.co.uk/suneedle/">http://www.mintylamb.co.uk/suneedle/</a><br></div><div><br></div><div><div><image.png></div><br></div></div></div><div>Good luck</div><div><br></div><div>mike h</div></div></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br><table style="border-top:1px solid #d3d4de"><tbody><tr><td style="width:55px;padding-top:13px"><a href="http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail" target="_blank"><img src="https://s-install.avcdn.net/ipm/preview/icons/icon-envelope-tick-green-avg-v1.png" alt="" width="46" height="29" style="width: 46px; height: 29px;" data-unique-identifier=""></a></td><td style="width:470px;padding-top:12px;color:#41424e;font-size:13px;font-family:Arial,Helvetica,sans-serif;line-height:18px">Virus-free.<a href="http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail" target="_blank" style="color:#4453ea">www.avg.com</a></td></tr></tbody></table><a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"></a></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 16, 2024 at 4:51 PM David Gott via Fot <<a href="mailto:fot@autox.team.net">fot@autox.team.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
Hi FOT,<div><br></div><div>Just put a Kent TR4-7 cam in my TR4; 300 duration. 3 laps at Summit point so far, and past half throttle under load, power cuts and air fuel enrichens to 10.5:1. BUT plugs are white. Was running an RC needle from the old cam, tried RA and not much improvement. Even when moving adjustment to full lean. The last test session is cancelled, so want to see air a best guess on a needle to try - figure someone must have experience with this cam and SU’s. 11.3:1 compression…. <br><br>Also, just put in a new HD condenser just in case it’s an ignition problem.</div><div><br></div><div>Any ideas or thoughts? Won’t be able to test the condenser until qualifying tomorrow, but air file holding steady at 2500 rpm shows 11.5:1 which seems way rich; old cam would be lean under those conditions.</div><div><br></div><div><br></div><div>Thanks for any ideas!!</div><div><br></div><div>Dave Gott<br><br><div><a style="font-size:12px" href="https://mail.onelink.me/107872968?pid=nativeplacement&c=Global_Acquisition_YMktg_315_Internal_EmailSignature&af_sub1=Acquisition&af_sub2=Global_YMktg&af_sub3=&af_sub4=100000604&af_sub5=EmailSignature__Static_" target="_blank">Sent from Yahoo Mail for iPhone</a><br></div></div>
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