Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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#219448 09/18/11 07:44 PM
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I put this in the Mechanical section but thought it might get more attention here.

I have a 1965 Checker that I was told has a Chevy 327 engine. The number on the front of the block is F06I611C. I was also told that the engine had been rebuilt in the late '80s and may have had new heads put on. Numbers on the heads are: 354484 and H11 76 and GM26T.

The spark plugs that I took out are Autolite 25. The manual calls for 43. 25s have beveled edges, and 43s have gaskets. The holes in the heads are beveled slightly, but I think that may be from over tightening the 25s. I had to use a breaker bar to get them loose. Any ideas?


Richard
Waverly, IA
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354434 is the casting number for 1975-1979 262, 267, and 305 heads There is no 354484.
The first small block with tapered plug seats was 1971 if I remember correctly.
There are no engone numbers that end with a single letter and by the '70's most ended with 3 letters.


Gene Schneider
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Originally Posted by Chev Nut
354434 is the casting number for 1975-1979 262, 267, and 305 heads There is no 354484.
The first small block with tapered plug seats was 1971 if I remember correctly.
There are no engine numbers that end with a single letter and by the '70's most ended with 3 letters.

Okay, the head number is 354434 and the block number is F06I6HC


Richard
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The HC was used in 1965 and 1966 for a 327 passenger car engine.


Gene Schneider
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Originally Posted by Chev Nut
The HC was used in 1965 and 1966 for a 327 passenger car engine.
Thanks!

So, with a 327 with 305 heads and 2 barrel carb, what would be a good spark plug to use?


Richard
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Richard,
I'd use a AC R45ts.
Don

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Thanks Don. That's what I was thinking, too.


Richard
Waverly, IA
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Originally Posted by Chev Nut
354434 is the casting number for 1975-1979 262, 267, and 305 heads There is no 354484.
The first small block with tapered plug seats was 1971 if I remember correctly.
There are no engone numbers that end with a single letter and by the '70's most ended with 3 letters.

Does the H11 76 indicate date of manufacture?


Richard
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Yes = 1976 + month and day


Gene Schneider
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Thanks guys! This is some good info to put in the owner packet for future reference.

Will the 305 heads increase the compression ratio? Or is the chamber the same size?


Richard
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The 305 heads for a 1976 gave about an 8.5 to 1 compression ratio on a 305. All else eing equal (no dished pistons, etc) the same heads would give a higher CR if used on a 327 block This is because the compression chamber to cylinder displcement ratio is changed. The 1976 327 engine used in a passenger car was also 8.5 to 1 if it was the base 327. I doubt if they would have used a higher CR head for the Checker as it would have required the use of premiimum fuel.
I would guess thar the CR with 305 heads would be up about one full point (9.5 to 1)....With timing set at the factory setting the engine would then require preimum fuel(at sea level). You could probably get by with 87 octane at your higher elevation...not sure about your 85 octane ,


Gene Schneider
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Originally Posted by Chev Nut
The 305 heads for a 1976 gave about an 8.5 to 1 compression ratio on a 305. All else being equal (no dished pistons, etc) the same heads would give a higher CR if used on a 327 block This is because the compression chamber to cylinder displacement ratio is changed. The 1976 327 engine used in a passenger car was also 8.5 to 1 if it was the base 327. I doubt if they would have used a higher CR head for the Checker as it would have required the use of premium fuel.
I would guess that the CR with 305 heads would be up about one full point (9.5 to 1)....With timing set at the factory setting the engine would then require premium fuel(at sea level). You could probably get by with 87 octane at your higher elevation...not sure about your 85 octane ,

Thanks Chevgene. I had a feeling that it would raise the CR a bit higher. My brother has always used 85 octane with no problem. We advance the timing about 6 degrees up here, but I also use a vacuum gauge to tweak it. It's always been a strong running engine.

In the past I've only fine tuned it for him after other people had tuned it, so I didn't know about the head change and needing different plugs until I asked him and he remembered they had done something to it back when he was driving it as a Taxi.


Richard
Waverly, IA

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