AC 41-900 Replaced with the 41-950 plug
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Northstar Engines and System Technical Discussion Discussion, AC 41-900 Replaced with the 41-950 plug in Cadillac Engine Technical Discussion; I'm goin to change my spark plugs this week and I just read my owners manual and it said the ...
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    freefaller07's Avatar
    freefaller07 is offline Cadillac Owners Member
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    AC 41-900 Replaced with the 41-950 plug

    I'm goin to change my spark plugs this week and I just read my owners manual and it said the AC plugs 41-900. I can't find these on the AC website. Were they replaced by the 41-950 and now obsolete or am I just not looking in the right place.

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    mcowden is offline Cadillac Owners Connoisseur
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    Re: AC 41-900 Replaced with the 41-950 plug

    The 41-900's and the 41-929's are obsolete. The 41-950 is the correct plug to use. The wires are 748J.
    Mike

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    freefaller07 is offline Cadillac Owners Member
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    Re: AC 41-900 Replaced with the 41-950 plug

    What is the gap for the plugs? I believe my northstar uses the the AC delco 628Q spark plug set.

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    mcowden is offline Cadillac Owners Connoisseur
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    Re: AC 41-900 Replaced with the 41-950 plug

    The gap is 0.050", the plugs are AC-Delco part number 41-950 and the wires are AC-Delco part number 748J.
    Mike

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    freefaller07's Avatar
    freefaller07 is offline Cadillac Owners Member
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    Re: AC 41-900 Replaced with the 41-950 plug

    I was just on the Rock Auto and AC-Delco website and I learned a lot. All the 1993 and 1994 Northstars use the AC 628Q wire set. All the 1995 to 1997 Northstars use the 748J wire set. I'm not sure what Northstars newer than 97 take for wires but I just thought I would clarify for future reference. Thanks for the help on the plugs though. The 41-950s are the ones.

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