'67 427 SPARK PLUG RECOMMENDATION

[Rob A.]

The '67 owner's manual specs call for AC43N. It has a dash (-) listed under city driving. Does this indicate no different plug is called for, or that the same plug for the 327 (AC45 or 46) is also recommended for big blocks?

[Clem Z.]

Re: '67 427 SPARK PLUG RECOMMENDATION

use AC R-45XLS with extended tip. these plugs stay clean around town and the fuel wash keeps the tip cool at hi RPM

[Richard S.]

Re: '67 427 SPARK PLUG RECOMMENDATION

Rob,
I don't know if there are any advantages to using newer technology plugs, however a wise old well known and respected NCRS guy who loved high horse big blocks and drove them a lot once told me that the best plug to use in both my 66 427/390 and 67 427/435 cars was the original plug. The AC43N's are still out there and they have worked great in both of my cars.