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1966-1967 GMH assembled Impala and Parisienne
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They are a rarer engine in the USA as they are COPO only for 1966 and 1967, from what I've heard most were for law enforcement or other Govt use. They aren't a high performance engine used in highway patrol or other Police spec cars, just a regular low compression engine but with the added performance of the 4BBL Rochester 4GC in 1966 and Quadrajet in 1967, so they could run on regular fuel not require the higher octane fuel like the L30 327 (275hp 10:1 engine). The low compression 4BBL 327 became a regular production engine in 1968 and that is what we got here in the 1968 Impala, Parisienne and GTS327, the 1968 engine having an extra 10hp (250hp) rating due to the bump in compression to about 9:1 courtesy of the 69cc heads whereas the 1966 (230hp) and 1967 (240hp) versions were just over 8.5:1, the 10hp jump from 1966 to 1967 was the Quadrajet. The reason it has a Saginaw cast intake is McKinnon weren't building 4BBL engines yet. Same with the Tonawanda block. Here is the GM20 dyno curve for the 1967 COPO low compression 4BBL 327:  Edited by user Saturday, 29 March 2025 1:04:12 PM(UTC)
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Joined: 8/12/2015(UTC) Posts: 20 ![Australia]( "Australia") Location: Victoria
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Thanks for the dyno. It is a high iron block and the heads were not any good so I have decided I will build it up as a 383 stroker and keep it. To think it will make 450hp and 500ft pound once I do the high lift and roller cam with 1.6 rockers and injection, is quite a difference. I will keep the bottom end components for future use.
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It’s not the best block to build a 377 stroker out of, you have to grind the mains down. Unless you manage to find one of the ultra rare 1963 Grand Sport 377 small journal 3.75” stroke crankshafts. The 1969 blocks are a lot stronger and have large journal mains. I’d just leave it as a 327 and find a 4 bolt with 386, 618, 388 or 010 castings if you want to build a 377. |
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Byron,
I have what I was told is a 327 out of an aust chev. Cast number on the block is 3782870.
Let me know what numbers you need off it to identify its origin
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Just the engine number pad. |
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1966-1967 GMH assembled Impala and Parisienne
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