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Mizzi's 1959 Star Chief Vista

2021 June
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Me and my 68 Firebird

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currently I have what I believe is a 350 YN code. But my dad and a mechanic seem to believe its a 400. I have researched and found no 400 to be a YN code. Also above the YN letters is 0283493. My research says its  base 350 with 265 HP. Could I be wrong? 

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3 hours ago, Bernardo1010 said:

Thanks, what are you driving?

I’ve got a Pontiac G6 and Chevy Camaro, can see them on profile in the garage app

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Hahaha thanks JUSTA6. Not seen in the picture is my 68 GMC. And soon to come is my older brothers 61 impala

thanks WRONGWAY & RINGO64 nice G6 and camaro. 

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Welcome to FP Bernardo.

Out of curiosity, does the numbers 283493 match the last digits of your car's VIN number? If it does, then that would mean that this 350 is the original engine that your car was built with.

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Thanks Frosty. The numbers on dash vin is what you are referring to right. Just my thought, the car has been well taken care of and from what my dad told me it is the original 350. But I will check tomorrow 

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That is correct sir. If it is the original motor the two numbers should match. 

That being said, assuming they match, the car is probably unmolested original. So you can swap motors and have fun, playing hot rod with the spare 421, but I would make sure to take real good care of the 350 since that is the engine it was born with. Numbers matching cars are worth more when you go to sell them.

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Update on the bird and it makes no sense to me. Casting numbers are 488988. YN code on the front. And FROSTY it is not matching the vin. So going forward I will eventually put the 428 in it.

And the heads are one of the three. 5C, 50, 56. I only found 5C for pontiac heads. Anyone know more about this situation

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Okay Bernardo. If 488988 is the casting number on the block, this matches up with a 1974 or 1975 Pontiac 400 block. You can tell by the date code stamped by the distributor hole. This further supports that this is not the original motor. Since you talk about having 5C heads, I am guessing you have a 1975 motor.

Photos help where you found these numbers on the heads.


I am assuming you found the 5C in the middle as shown above.

5C heads from 1975 could be one of the following heads:


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