Obsessing about thermostats and bypass

The brass bypass plate is more or less permanently pressed into the engine block and it is doubtful that it has been removed. Easy to check, however

to determine if your current thermostat is correct go to the link you provided for flow cooler. They depict the correct high flow thermostat which must have the “hat” on the movable plunger that indexes with the bypass plate

note there are standard flow and high flow thermostats, the high flow is what is pictured at flow cooler.

The correct thermostat for our Cleveland engines is a high flow with the hat. Any other choices will most likely cause you cooling issues

Larry

When in doubt ...

https://www.tmeyerinc.com/prod.../335-cleveland/351c/

Also, use one of these for refilling your cooling system:

https://www.amazon.com/OEMTOOL...filler/dp/B01GSQA5BI

the "hat" needs to be the correct diameter to fit into the brass plate's hole

when cold the hole for bypass is open and no coolant to radiator

when warm, the hat will start throttling the coolant and reduce bypass

when hot the hat has the hole nearly plugged so virtuatlly no bypass

when real hot the body of the thremosat contacts the plate

the 333 (correct dimensions)

the 330 has a hat BUT its the wrong dimensions

and would not throttle allowing more bypass (and less to radiator)

Thanks all. Super helpful as always. Does anyone know if the Balkamp BK 8251007 has those dimensions? I can't find specs and don't want to pull it out if it "ain't broken". I suppose I should pull it just to be sure the plate is there.

Thanks for the tip on the system refiller/evacuator tool.

The Cleveland is the only Ford small block with an internal coolant bypass. All other Ford small blocks have an external bypass hose. That hose is always in play, never blocked.

my understanding is the hat on a Cleveland thermostat is not intended to completely seal the bypass opening, but allows a similar amount of permanent bypass as found in the other Ford small blocks

Larry

...the Original 351C Thermostats are again being produced at Tmeyer.com

The Best Brass Restrictor Plate can be purchased on Ebay.

MJ

Thanks guys. I bought the Robertshaw 333 and plate from FlowKooler (link in first post). Will do a comparison with the Balkamp when I get it.

A follow up: The Robertshaw 333 arrived and looks identical to the Napa/Balkamp.
https://www.napaonline.com/en/p/BK_8251007
My block DID have the brass plate installed. If anyone needs either or both a new plate and a used Balkamp thermostat, let me know and I'll send them to you.

NAPA says this Balkamp does NOT fit a Pantera.

jmardy,

is it possible for you to post top and bottom photos of the Belcamp thermostat??

Larry

@lf-tp2511 Hi Larry,
Here they are:

                                                          ...Listen to the facts! NO 'Skirts'! You Have Two of the Wrong Thermostat! I'am going to say this once more... Tmeyer.com  has the correct RS Thermostats. With 'Hats', understand That!

...Take it from someone who has modified well over 640, (Quality Controlled and Documented) of the 330 RS Stats. All for the good of the 351 Cleveland.

MJ

Marlin is a machinist who arguably has unsurpassed knowledge on our Cleveland thermostats and the block off plate.

he is correct that neither of the thermostats pictured is designed for a Cleveland engine. Neither of them appear to have the hat that is designed to properly index with the block off plate opening.

as Forest pointed out earlier, the part number does not reference to a Cleveland engine.

you are not the first to go down this road but until you install a thermostat with a hat you have not fixed your thermostat problem

Go online and order one from Tim Meyer and all will be good.

Larry

Well sh!t. Glad I posted the pics. Thanks Larry, MJ!
Any point in getting his bypass plate while I'm there?|
(besides they're pretty?)

I’m sure the only point in buying a new restrictor plate would be to increase Tim‘s income, which is a nice thing for him but I’ll leave that decision to you  

OEM plate is more than sufficient and removing them is a true PITA.

Larry