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Chuck;
That heater core port on the back of the head provides flow to an otherwise=
blind spot in the head over an exhaust valve. =C2=A0On a race car without =
flow through that port it could lead to early exhaust valve failure. =C2=A0=
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. =C2=A0We control the flow=
by using a 5/16 line, providing some flow but not overly bypassing anythin=
g. =C2=A0
=C2=A0Note that blocking that flow on a street-driven engine is OK as the e=
xhaust valve is not overly stressed during street driving compared to what =
we do on-track!
Hope this helps.
Phil
On Tuesday, January 20, 2026 at 04:16:51 PM EST, Chuck Gee via Fot <fot=
@autox.team.net> wrote: =20
Hello all,
In an effort to constantly improve the car, I=E2=80=99ve been looking at th=
e cooling system on my TR4.=C2=A0 It currently has a header tank mounted to=
the firewall that functions as the high spot in the system.=C2=A0 This tan=
k feeds the top of the radiator but doesn=E2=80=99t really circulate during=
operation.=C2=A0 I=E2=80=99ve been thinking of plumbing the feed off of th=
e back of the head into the top of the tank so that it circulates.=C2=A0=20
Normally this rear head feed is plumbed to the back of the water pump.=C2=
=A0 In an exercise of overthinking, I=E2=80=99m not sure if there will be s=
ufficient circulation since the tank is plumbed to the radiator.=C2=A0 Does=
it matter?=C2=A0 What is the collective wisdom?
Here are some pictures to help illustrate.
Thanks,
Chuck
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
com
=20
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<html><head></head><body><div class=3D"ydp223f9f02yahoo-style-wrap" style=
=3D"font-family:arial;font-size:16px;"><div></div>
<div dir=3D"ltr" data-setdir=3D"false">Chuck;</div><div dir=3D"ltr"=
data-setdir=3D"false"><br></div><div dir=3D"ltr" data-setdir=3D"false">Tha=
t heater core port on the back of the head provides flow to an otherwise bl=
ind spot in the head over an exhaust valve. On a race car without flo=
w 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 pum=
p, 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=3D"ltr" data-setdir=3D"false"><br></div><div dir=3D"lt=
r" data-setdir=3D"false"> Note that blocking that flow on a street-dri=
ven engine is OK as the exhaust valve is not overly stressed during street =
driving compared to what we do on-track!</div><div dir=3D"ltr" data-setdir=
=3D"false"><br></div><div dir=3D"ltr" data-setdir=3D"false">Hope this helps=
.</div><div dir=3D"ltr" data-setdir=3D"false"><br></div><div dir=3D"ltr" da=
ta-setdir=3D"false">Phil</div><div dir=3D"ltr" data-setdir=3D"false"><br></=
div><div dir=3D"ltr" data-setdir=3D"false"><br></div><div><br></div>
=20
</div><div id=3D"yahoo_quoted_9332275551" class=3D"yahoo_quoted"><d=
iv class=3D"yahoo-style-wrap" style=3D"font-family:arial;font-size:16px;">
<div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
=20
<div class=3D"quoted-text-header">
On Tuesday, January 20, 2026 at 04:16:51 PM EST, Ch=
uck Gee via Fot <fot@autox.team.net> wrote:
</div>
</div><div style=3D"font-family:'Helvetica Neue', Helvetica=
, Arial, sans-serif;font-size:13px;color:#26282a;border-left: 1px solid #cc=
c;padding-left: 8px;margin: 0px 0px 0px 8px" class=3D"inline_reply_quote_co=
ntainer">
<div><br></div><div><br></div>
<div><div dir=3D"ltr">Hello all,<br></div><div dir=3D"ltr">=
<br></div><div dir=3D"ltr">In an effort to constantly improve the car, I=E2=
=80=99ve been looking at the cooling system on my TR4. It currently h=
as 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=E2=80=
=99t really circulate during operation. I=E2=80=99ve 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=3D"ltr"><br></div><div dir=3D"=
ltr">Normally this rear head feed is plumbed to the back of the water pump.=
In an exercise of overthinking, I=E2=80=99m not sure if there will b=
e sufficient circulation since the tank is plumbed to the radiator. D=
oes it matter? What is the collective wisdom?<br></div><div dir=3D"lt=
r"><br></div><div dir=3D"ltr">Here are some pictures to help illustrate.<br=
></div><div dir=3D"ltr"><br></div><div dir=3D"ltr">Thanks,<br></div><div di=
r=3D"ltr"><br></div><div dir=3D"ltr">Chuck<br></div><div dir=3D"ltr"><br></=
div><br>_______________________________________________<br><a ymailto=3D"ma=
ilto:fot@autox.team.net" href=3D"mailto:fot@autox.team.net";>fot@autox.team.=
net</a><br><br><a href=3D"http://www.fot-racing.com"; target=3D"_blank">http=
://www.fot-racing.com</a><br><br>Donate: <a href=3D"http://www.team.net/don=
ate.html" target=3D"_blank">http://www.team.net/donate.html</a><br>Archive:=
<a href=3D"http://autox.team.net/archive"; target=3D"_blank">http://autox.t=
eam.net/archive</a> <a href=3D"http://www.team.net/pipermail/fot"; target=3D=
"_blank">http://www.team.net/pipermail/fot</a><br>Unsubscribe/Manage: <a hr=
ef=3D"http://autox.team.net/mailman/options/fot/vfracing@aol.com"; target=3D=
"_blank">http://autox.team.net/mailman/options/fot/vfracing@aol.com</a><br>=
<br><br></div>
</div>
</div></div></body></html>
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_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
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