[Fot] Collective wisdom

[vfracing at aol.com]

 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.  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.  
 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!
Hope this helps.
Phil


    On Tuesday, January 20, 2026 at 04:16:51 PM EST, Chuck Gee via Fot <fot at autox.team.net> wrote:   

 Hello all,

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.  

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?

Here are some pictures to help illustrate.

Thanks,

Chuck


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