INFO: Thermostat for 351 Cleveland, 351M or 400

Which thermostat will do? Robertshaw333 high flow......?Tridon High flow? Others...?

Any info is good....thanks....

i've heard the 'hat' can be removed from a correct thermo and installed onto a Windsor, generic / chevy style thermo and it becomes the Robertshaw 333 series. the only difference between the Windsor and Cleveland thermos from Robertshaw was the presence of the bypass restrictor hat installed onto the temp sensor bulb. other than that the 2 thermos are identical. supposedly the tooling for making the hats was worn out or damaged and Tim Meyer www.tmeyerinc.com bought the tooling, had it repaired and is having some outfit producing correct 333 style thermos available new in the box (NIB) but out of stock for the near & distant future.

FWIW you can source correct thermos from Rockauto for under $5, search under 351 cubic inch and make sure you specify Q code for the VIN and look at the pic if it's available. this will get you the correct Cleveland specific thermo, i don't trust their listings for 400. example look at RT351, it doesn't have the hat yet they're spec'ing it for a 400 which also uses the same internal bypass system as the 351C. all the listings have been corrupted by data entry incompetents that knew nothing of the items they were uploading into the system when they went from actual paper books to computer. it'll never be right again

custom made hats and restrictor plates are available from ebay seller neonfiddler but not cheap.

i forgot to mention Q code only 1971.5 - 1974, from 1970 - 1971.5 it was M code

i usually look up for 1972 to avoid the mid-year break but M code should be 351C specific and correct also

4bbl leaves open the possibility of getting a Windsor stat, there were some 351W-4V's

H code can be a Cleveland, Windsor or 351M depending upon model year, high likelyhood of  getting the wrong stat

no telling where that freak belongs

from the listed applications i'd scratch it off the list most ricky ticky

click on the highlighted part number

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there sure enough was a Q code in 73 and 74, that's what i mean about the listings being fubar'd,

yeah we just have to be smarter than the confuser in front of us

here's a great explanation of how the system works

IDK why sometimes my links work and sometimes they don't?

 

 This is the only style thermostat that should be used. The other hat designs do not flow enough coolant when open and cause the coolant path to continue to circulate in the block. The shaw design addresses the flow issue with the huge top opening allowing coolant from the radiator top hose to easily be pulled into the block. Having the lower hat to block the plate is a must but the big issue with this block is flow. The shaw thermostat was in the car from ford. If you look at the top of the others you can see how small the opening is compared to the shaw design.

The Robertshaw 330 series looks like the 333 series from the top, but flip it over & they're not the same. The 330 series is the universal thermostat that fits small block Fords, small block Chevys and small block Mopars.

That's also one way to determine what Mr Gasket & others are selling ... search which motors the thermostat fits. The 333 series fits 351C, 351M and 400 only. And a thermostat that fits 289/302/351 Fords, small block Chevys or small block Mopars will not work properly in a Cleveland.

Ford has used the Robertshaw high flow thermostat in many applications since the 1960s, and I believe they still use it today. They all look the same from the top, but only the one designed for the 351C has the little 11/16" flanged button on the bottom. Its a small subtle difference that many people don't understand. This thermostat is unique to the 335 series motors (351C, 351M, 400) and no other motor uses it.

Even Ford has sold the wrong thermostat over the counter in the 1970s! They actually boxed the wrong thermostat in the box of the right part number. Check out techincal service bulletin number 9, page 11.

My advice is to use the 333-192 thermostat. The original 351C thermostats were 192 degree thermostats.

The above info is from George Pence on the Pantera forum and helps to select the correct thermostat. I run the 333-192. The reason for the 192 degree is the 335 series tends to collect condensation under the intake at 180 degrees and running around 192 clears that issue up.

Hope this helps clear things up, it helped me out as I had the hat style small opening in before and it made a big difference in cooling stability in any situation when I switched to the 333-192 on my Cleveland.