Spark Plugs For 289

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   I have searched high and low for spark plug information for my 1968 Mustang with a 289 engine. I'm hoping someone on the forum can provide some information.

Here's what I know: My existing plugs are 5/8" hex, stainless steel, tapered seat, (this much I am sure of) with a longer than what I am used to seeing reach. The Motorcraft part number is a ASF32CM. These plugs are non-existant as far as I can tell.  All the spark plug sites I visit are vague on spark plug specs.

Anyone know what the proper thread diameter and heat range is for the Ford 289 marine engine? The threads are either 10mm or 14mm but I don't know which. Does anyone know?

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Jim_In_Houston Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120	Post Options Post Reply Quote Jim_In_Houston Report Post Thanks(0) Quote Reply Topic: Spark Plugs For 289 Posted: October-02-2004 at 12:42pm
	I have searched high and low for spark plug information for my 1968 Mustang with a 289 engine. I'm hoping someone on the forum can provide some information. Here's what I know: My existing plugs are 5/8" hex, stainless steel, tapered seat, (this much I am sure of) with a longer than what I am used to seeing reach. The Motorcraft part number is a ASF32CM. These plugs are non-existant as far as I can tell. All the spark plug sites I visit are vague on spark plug specs. Anyone know what the proper thread diameter and heat range is for the Ford 289 marine engine? The threads are either 10mm or 14mm but I don't know which. Does anyone know?

reidp Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804	Post Options Post Reply Quote reidp Report Post Thanks(0) Quote Reply Posted: October-04-2004 at 1:43am
	Jim, Not that it's gonna completely solve your plug issue, but lets start here: * A 1968 Ford 289 head would use a 13/16" plug and not a 5/8", which leads me to believe your heads have been replaced with later model - 1976+ 302/351 pieces. Since your heads are on the engine you can't read the casting number underneath, which identify the year number. Check and see if that Motorcraft plug part number, if you haven't already, matches or at least cross references with a later 302-351 engine more recent than 1975. Let us know what you find out. Reid
	ReidP 1973 Mustang

Jim_In_Houston Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Platinum Member Joined: September-06-2004 Location: United States Status: Offline Points: 1120	Post Options Post Reply Quote Jim_In_Houston Report Post Thanks(0) Quote Reply Posted: October-04-2004 at 3:38am
	Wow. Good info. Thanks. The plugs are definatly 5/8". I had to take a trip to Sears to buy a new spark plug socket. The previous owner advised me that the engine was rebuilt once because of a cracked block resulting from incorrect winterizing. Maybe the mechanic dropped in a used 302 or 302 heads. More identifing clues would be appreciated. I'll check the 302 plugs for a cross reference. THANKS!!!

Spark Plugs For 289

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