Spark Plug difference

[GTSpecial39]

I am still working on my 351C M code with the new 650 Holley carb. I just picked up ASF-32C SP415's and when I got home, one box of 4 plugs are ASF-32CA's. So wondering if I could have a problem with 4 C's and 4 CA's or if I need to take one of them back to exchange them. I also have a Pertronix distributor and ignition system on it. From where I live its 40 miles to the part store.....lol Any infor would be appreciated!! Thanks GT

 

[secluff]

Hello GT,
These plugs went through a series of part number changes. Some were packaging changes, and others we felt were the engineers' attempts to justify their positions by keeping the parts personnel and customers confused by the constant barrage of part number changes.
The original plug part number is
ASF-32C (Motorcraft SP-415) → Replaced by ASF-32CA (Motorcraft SP-415A) → Replaced by ASF-32CX (Motorcraft SP-415X) → Replaced by ASF-32CAX (Motorcraft SP-415AX)

This is Ford's official succession of number changes, so all are compatible and interchangeable.

 

[Stanglover]

I just run Autolite 24's in my M code and with the stockish set up, no problems.

 

[GTSpecial39]

Hello GT,
These plugs went through a series of part number changes. Some were packaging changes, and others we felt were the engineers' attempts to justify their positions by keeping the parts personnel and customers confused by the constant barrage of part number changes.
The original plug part number is
ASF-32C (Motorcraft SP-415) → Replaced by ASF-32CA (Motorcraft SP-415A) → Replaced by ASF-32CX (Motorcraft SP-415X) → Replaced by ASF-32CAX (Motorcraft SP-415AX)

This is Ford's official succession of number changes, so all are compatible and interchangeable.

Thank you, wish they would keep things simple....lol The 32C family should be gapped at the .035? Do appreciate your input!!!

 

[basstrix]

I also run Autolite 24's and gap them to .040. Your ignition system will play a role in how wide you can gap. Engine masters did a show on this and plug gap only made a slight improvement in power. That's wide open throttle testing and the wide gap used by the Duraspark-I, for example, was more to ignite the very lean mixtures needed to pass California emissions.