351C Cleveland Thermostat Bypass System

[ThumperNZ]

I'm building a 407ci Ford Cleveland road race engine for historic class racing. We're using an Australian Arrow block.
The query I have is related to the 351C cooling thermostat bypass plate size.
The 351C cooling system uses a thermostat which has a foot, which when open diverts the bypassing coolant to the rest of the engine and radiator.
Many 351C users who experience overheating are using the conventional thermostat which means that the coolant is operating in bypass mode, not feeding the radiator. This has been reported in many Ford forums.
The thermostat that is supplied, and I have been assured is correct, is the Tridon TT2023-170 or 180. This has a foot diameter of 16.8mm or 0.66".
The opening that is the bypass that is sealed, is 19.05mm or 0.75".
So this leaves 1.12mm of gap around the thermostat , so it's not really a seal, I calculated this to be just under 1/10th sq in, or equal to a hole size of 0.356" dia.
So I'm a bit confused, it's still bypassing a good amount of coolant, or has the thermostat maker made these thermostat foot diameters too small?

[sportsroof]

Don't know if this will help but I raced a 351C here in the UK for about 12 years and at first had some overheating even with a good new radiator.
Here is what I found worked: http://351c.net/board/index.php?/topic/ ... mment-8109
No overheating issues with all-iron 351C, around 450hp (Historic racing) in 40 minute circuit races. HTH
Cheers, Martin

[Walter R. Malik]

To help avoid water pump cavitation with a crankshaft driven water pump, the by-pass should never be fully closed-off.
We simply use a regular thermostat and epoxy a flat, round piece of sheet metal in that by-pass hole with a 1/4" or 6mm hole drilled in it.

As above, the welsh plug in the front block face with a drilled hole will work just as well but, the water pump and front block-off plate must be removed to be able to do it.

[1972ho]

https://www.tmeyerinc.com/product/high-flo-thermostat/ Have you checked Tim meyer’s sight.