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High comp 472 vs. low comp 500

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  • tremorj10
    Thanks to Richard for this post: Hey Parnell- My 70 Fleetwood with the 10:1 472 runs like a Swiss watch on 89 octane when it s lightly loaded and the ambient
    Message 1 of 1 , Aug 31, 2002
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      Thanks to Richard for this post:

      Hey Parnell-
      My '70 Fleetwood with the 10:1 472 runs like a Swiss watch on 89
      octane when it's lightly loaded and the ambient temperature is no
      more than 85 or so (engine temp 180-190). When it's heavily loaded
      and the temperature goes above 95 (engine temp 210-230) not even
      straight 93 octane will keep it from rattling.

      My '69 LeMans with an 8.5:1 500 never knocks on 87 octane with the
      factory spark timing. The weight difference between the LeMans with
      me in it and the Cad with a full load is easily over 1000 pounds,
      which makes a big difference too. If you're thinking about which
      engine to put in a 7000 (I hear) pound hearse, the 8.5:1 engine would
      definitely be the way to go.

      Richard
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