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Old 10-10-2024, 03:57 PM
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Default Thermostat different in 1971 YS intake manifold

In my 1971 Firebird Formula I have the original intake manifold from the original YS motor. I am putting and original 1971 YS motor that I located. It is complete and un messed with. It came back from the Machine shop and I'm putting the final touches on it before going in my car. My original manifold takes a larger diameter thermostat than the motor that I'm putting in. The original motor was from California. The new motor is from Atlanta. Both are same cast numbers and within 7 days of each other. 3/10/71 & 3/17/71 Why are they different??
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  #2  
Old 10-10-2024, 04:07 PM
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Pictures of both intakes showing thermostat opening, date, and casting number?

All engines were built in Pontiac and then shipped to the assembly plants for installation.
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  #3  
Old 10-10-2024, 05:15 PM
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Here is the motor I'm putting in (3/10/71). NAPA shows both thermostats for 1971 Pontiac Firebird 400 motor. The original is in the car (3/17/71).
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Old 10-10-2024, 07:34 PM
Formulas Formulas is offline
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i dont think the stat on the right is correct, never seen one with that lower appendage (for old school pont)

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Last edited by Formulas; 10-10-2024 at 07:48 PM.
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Old 10-10-2024, 09:03 PM
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https://www.napaonline.com/en/p/BK_8251007
Aftermarket.

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Old 10-10-2024, 10:32 PM
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The unit on the left looks like a Robertshaw “high flow” type thermostat.

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