273 or 318?

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JTinAZ

JTinAZ

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I’m trying to determine if I have a 273 or 318. There is too much grud on the block for me to get to the numbers right now but I was able to identify the stamping below the DS head. It’s 8490556. I can’t find anything with this number. Do I need to clean the block and find the casting numbers?
 
JTinAZ said:
I’m trying to determine if I have a 273 or 318. There is too much grud on the block for me to get to the numbers right now but I was able to identify the stamping below the DS head. It’s 8490556. I can’t find anything with this number. Do I need to clean the block and find the casting numbers?
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Yes. Clean the block. That's a later model number so it has to be a 318.
 
Just look to the left on that stamping below the cylinder head and it will say the cubic inches.
 
What year do you think it is?



Front of engine, drivers side
C = 67 model year
273 = displacement
12-21 = December 21, 1966 engine build date
Screenshot_20240702-221230~2.png
 
If only my engine looked like that! Lol

I did find and R and 2 in front of the 8490556 after further inspection but still no cid stamp. Still no luck with that number either.

Between all the old oil and grud, the exhaust manifold, and the frame rail, I can’t see squat. I was hoping the stamped numbers would tell me what I needed without getting elbows deep with a wire brush and a pressure washer. Guess not!
 
So I used a scotch pad and revealed the full stamping. It is in fact a 273. The full number is PM273R 28490556.
I’ll have to clean the block up at some point to find a date code. I still suspect it’s not a 69 because it’s not red but I saw a low mileage original 69 recently with a 318 that was also turquoise so maybe they didn’t paint all the 273 and 318’s red in 69 as I had read.
 
PM 273

Is most likely BM 273. 66 model year.

Which is good, has modern intake bolt holes.
 
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