<html class="apple-mail-supports-explicit-dark-mode"><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">I’ve never understood overflow tanks to need “flow”. Plz correct me if I’m wrong, but i thought they were there just to provide for the expansion and contraction of coolant when heated, etc<br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Sent from my iPhone</div><div dir="ltr"><br><blockquote type="cite">On Jan 20, 2026, at 6:31 PM, vfracing--- via Fot <fot@autox.team.net> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div class="ydp223f9f02yahoo-style-wrap" style="font-family:arial;font-size:16px;"><div></div>
<div dir="ltr" data-setdir="false">Chuck;</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">That heater core port on the back of the head provides flow to an otherwise blind spot in the head over an exhaust valve. On a race car without flow through that port it could lead to early exhaust valve failure. The best way to ensure flow is to plumb it to the intake side of the water pump, set up as if there were a heater installed. We control the flow by using a 5/16 line, providing some flow but not overly bypassing anything. </div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"> Note that blocking that flow on a street-driven engine is OK as the exhaust valve is not overly stressed during street driving compared to what we do on-track!</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Hope this helps.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Phil</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"><br></div><div><br></div>
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On Tuesday, January 20, 2026 at 04:16:51 PM EST, Chuck Gee via Fot <fot@autox.team.net> wrote:
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<div><div dir="ltr">Hello all,<br></div><div dir="ltr"><br></div><div dir="ltr">In an effort to constantly improve the car, I’ve been looking at the cooling system on my TR4. It currently has a header tank mounted to the firewall that functions as the high spot in the system. This tank feeds the top of the radiator but doesn’t really circulate during operation. I’ve been thinking of plumbing the feed off of the back of the head into the top of the tank so that it circulates. <br></div><div dir="ltr"><br></div><div dir="ltr">Normally this rear head feed is plumbed to the back of the water pump. In an exercise of overthinking, I’m not sure if there will be sufficient circulation since the tank is plumbed to the radiator. Does it matter? What is the collective wisdom?<br></div><div dir="ltr"><br></div><div dir="ltr">Here are some pictures to help illustrate.<br></div><div dir="ltr"><br></div><div dir="ltr">Thanks,<br></div><div dir="ltr"><br></div><div dir="ltr">Chuck<br></div><div dir="ltr"><br></div><br>_______________________________________________<br><a ymailto="mailto:fot@autox.team.net" href="mailto:fot@autox.team.net">fot@autox.team.net</a><br><br><a href="http://www.fot-racing.com" target="_blank">http://www.fot-racing.com</a><br><br>Donate: <a href="http://www.team.net/donate.html" target="_blank">http://www.team.net/donate.html</a><br>Archive: <a href="http://autox.team.net/archive" target="_blank">http://autox.team.net/archive</a> <a href="http://www.team.net/pipermail/fot" target="_blank">http://www.team.net/pipermail/fot</a><br>Unsubscribe/Manage: <a href="http://autox.team.net/mailman/options/fot/vfracing@aol.com" target="_blank">http://autox.team.net/mailman/options/fot/vfracing@aol.com</a><br><br><br></div>
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