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Discussion Starter #1
Hey everyone. I’m about order some valve covers for my 66 Impala from Hubbard’s Impala parts. It has a 327 Turbo Fire engine but is not an SS. I need help figuring out how much horsepower my engine has so I can get the correct valve cover stickers. Here’s some pics of my engine and the valve cover. I was told it has double hump heads.

Also, were all 327 engines “Turbo Fire” or were these just some with more horsepower?

Thanks guys.
 

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The best thing to do is to get the Engine Code off the Front Pad.

Then we can tell you better exactly what you have there.
 
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HCH = 1966 327 275 PG B. Holley

1966, 327, 275 HP, Powerglide Trans, Full Size Chevy, with a Holley Carb
 

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Your engine is a 275 horse. It isn't sporting a Holley, that is a Carter AFB. Turbo Fire is what Chevy called all SBC motors. Turbo Jet was used for all big blocks and Turbo Thrift was use on all in line sixes. Your double hump heads Are most likely a 1.94/1.60 inch (up from the 1.72/1.50 inch valves found in the power pack head commpn to the 327 and introduced in 1957 on the 283. Those heads combined with a Duntov 30-30 solid flat tappet cam and a Carter AFB was rated at 340 horse. With a Rochester mechanical fuel injection unit (why the double hump heads are called Fuelie heads) that 327 was rated a 365 horse.

You have an interesting combination of parts. You need to check the date codes to see if they were all around your assembly date on the trim tag.

Horsepower rating was based upon the Heads, with matching pistons to get a higher static compression ratio, then the cam adds to the mix. Induction and exhaust don't make power but they can certainly take it away from any combination. You really can not believe the rated horsepower because a Corvette always had more horsepower than any one else even though it used the same engine as the Impala. That was a marketing decision. Another marketiong decision was uping the 275 horsepower from one year to the next to compete with Chryslers 300 horsepower with a 392 Hemi in the Chrysler 300 . The 300 horse engine suses the exact same parts (heads, cam, pistons and carb) as the 275 horse did it just need more Avertised power to compete with Chrysler to sell cars.

Big Dave
 

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L30

The 1966 Impala 327 was 275 HP, it is the only 327 available for the 1966 Full Size car. The valve covers did have the engine displacement along with HP rating. The air cleaner did not have the engine rating nor HP rating, that began in 1967.
See my video of my car, scroll forward to L30 :

Second half if you’re interested:

Paul
 

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Discussion Starter #11
The 1966 Impala 327 was 275 HP, it is the only 327 available for the 1966 Full Size car. The valve covers did have the engine displacement along with HP rating. The air cleaner did not have the engine rating nor HP rating, that began in 1967.
See my video of my car, scroll forward to L30 :
https://youtu.be/V3ArnG1s_LY

Second half if you’re interested:
https://youtu.be/9gqlLbFTRuo

Paul
Thanks for the info. That’s one nice looking 66 you have there!
 
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