Engine Block Code-Non Corvette

[Barry #41479]

My brother has bought a 67 Firebird and it has a non-orignal engine with block stamp codes "C030179 Y4". Does anyone have any ideas on what it is and what it came out of? I think that is is a Pontiac 455 from the early 70's but am probably totally off base.

Any information much appreciated.

[William C.]

Re: Engine Block Code-Non Corvette

How about a casting number and date?

[Barry #41479]

Re: Engine Block Code-Non Corvette

I'll try to go by there and look at it. He says he cannot read the info. Thanks for your help.

[Roger Legge]

Re: Engine Block Code-Non Corvette

While they certainly could have been changed, look at the heads, top of the center two exhaust ports and you'll see something like a 6X, 6H, or 4X cast there, sort of big letters. It could be either a two character or three character code. Also, there should be a block casting number back by the distributor hole on the top of the block. One more thing, a 455 will have a '455' or maybe even a '55' cast on the side of the block - again, fairly big numbers.

Roger

[Roger Legge]

Re: Engine Block Code-Non Corvette

These are the Y4 code possibilities. All were originally auto trans cars.

Year Size Head Block Casting #
1972 455 7M5 485428
1973 400 4X 481988
1974 455 4X 485428
1976 455 6H 500813 (early)
1976 455 6X 500813
1977 400 6X 568557

Lots of torque in those Pontiacs!

Roger