[Fot] Collective wisdom

[JS Performance Motoring, LLC]

  Chuck,  the header tank setup I have used on GT6's and Spitfires has two
feeds to the top of the tank:  One from the thermostat housing (or top of
the rad), and the other from the rear of the head as you are considering.
To encourage some circulation, the bottom of the header tank should be
plumbed to the suction side of the system:  backside of water pump housing,
or the bottom of the rad.

I mostly use 1/4" lines for this, trying to somewhat limit the amount of
flow to "just enough".





Jason Sukey
JS Performance Motoring, LLC
440.984.7720
jason at jsperformancemotoring.com
www.jspmparts.com
https://www.facebook.com/JSPerformanceMotoring/


On Tue, Jan 20, 2026 at 4:13 PM 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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