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I have a 351w where i have replaced the thermostat. I'm worried that i did not replace it correctly or that some parts are incorrect. Because after installation (torqued to spec). If i reach through the thermostat housing i can wiggle the thermostat a little bit. Is the thermostat supposed to be retained (clamped) better? I'm worried that it could wiggle itself upside down.

When i assembled this i cleaned all surfaces and torqued to spec with the air bleed hole at the top. I did not use any RTV or glue. Only the gasket.

Parts:
  • Edelbrock Part # 7181 Performer RPM 351W intake manifold
  • Motorcraft Thermostats XR3Z8575BA
  • Thermostat housing of unknown origin marked (CHINA) on the bottom (Looks like Dorman Thermostats 902-1001)
  • Fel-Pro Water Neck Gaskets 35440

Do i have the wrong parts or did i assemble this incorrectly?
 

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Hate to be the bearer of bad news.....but I also tried a Dorman 902-1001 and found it isn't quite right....the bypass hose size is 3/4 instead of 5/8 and the gasket surface doesn't follow the manifold face very well right at the top...way to thin!......they do list that part number as fitting for a SBF...I found that a Four Seasons 84831 which is also sold by Dorman was the correct part number....But looking up that part number sometimes gives you a 902-1001...agh! I found the correct part at...CJ pony parts and order it anyway and got it. If yours is a 1968 then you may have a 3/4 bypass hose...check your sizes...

sandybob

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t pic is 902-1001 and second is Four Seasons 84831.. CJ's does NOT list it with that part number...but that's it.
 

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Being slightly loose may help with purging the air sometimes trapped in the intake manifold. I usually drill a small hole, 1/16", in a thermostat before I install them and make sure it is oriented at the top. Some thermostats are furnished with a rubber seal that fits over the thermostat edge and probably holds them tight.

Four Seasons from Rockauto, FOUR SEASONS 84831 Thermostat Housing / Water Outlet | RockAuto
 

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Are you going strictly by the picture? All the numbers on that RockAuto page say its 84831 !?!
Hey DustyB :) Well having seen other parts places list this part wrong..........Yea...I guess I am....anyone want a Dorman 902-1001 for free?....I still have it and it's no good to me....

Hey...Have a good one............

sandybob
 

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It won't matter if it's upside-down, right-side up or sideways, nor do you really need the hole drilled in it, unless you're working on an "Other Make" that doesn't have the bypass hose in the thermostat housing. Even if you didn't have the turbulence of the coolant flow at the thermostat, itself, the most of an air bubble you'd get behind the thermostat would be about the size of a kidney bean and wouldn't amount to squat.
 

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I never gave that bypass hose any thought. I believe you may be right
 
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