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  1. #1
    Join Date
    Aug 2019
    St. Louis , MO

    Default 2004 launch spark plugs

    Bought a 2004 Launch at the end of last summer and had it out a few times before winter. Being doing a lot of needed maintenance and ran into a snag on replacing spark plugs. Original manual called for AC 41-932. It is no longer available and the replacement seems to reference the AC 41-993. Also, the plugs I took out were AC MR44T. This old plug is 5/8" of an inch shorter than the new plug and the information I found show them to be for mid-seventies GM's. The guy I bought the boat from was not a mechanic. I'm pretty sure he picked these up cheap at the parts store. I'm calling Indmar tomorrow, but wanted to see if anyone had some input. I've put on new wires, cap, rotor fuel filter and am rebuilding the throttle body. Also replacing all the burned out lights with LED's, along with new wiring from front to back on the trailer. Boat only had 300 hours on it and wasn't abused but it wasn't pampered either.

    (Update) Called Indmar and they told me to stick with the AC MR43LTS. The 41-993 plugs are replacements for newer engines with CATS.
    Last edited by secondsupra2004; 05-03-2020 at 09:18 PM.

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