355 spark plugs: CR7EIX may not be a cross reference for the PMR7A | FerrariChat
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355 spark plugs: CR7EIX may not be a cross reference for the PMR7A

Discussion in 'Technical Q&A' started by f355spider, Nov 19, 2006.

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  1. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
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    #1 f355spider, Nov 19, 2006
    Last edited by a moderator: Sep 7, 2017
    Notice the difference in the length of the projected tip? What would be the negatives of the CR7EIX being short by about 3mm or so?

    This was just brought to my attention recently.
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  2. No Doubt

    No Doubt Seven Time F1 World Champ

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    #2 No Doubt, Nov 20, 2006
    Firing further away from the piston, whether from a shorter spark plug or shaved piston, would seem to me to have the same effect as advancing the ignition timing (in the sense that the flame front has a greater distance to travel).

    Except that the flame front would have less average time to travel that distance (greater distance, same overall time) which in that sense would be like retarding the timing.

    And compression would be minutely lower.

    ...seems like you'd get negatives across the board.
     

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