There are numerous old posts on this topic. This is from the most recent one that I had replied to. "As long as you still have the factory '73 heads, Autolite AP45 or APP45's are what you're looking for. AP45 are standard platinum and APP45 are double platinum. These came out of my older catalogue so hope the part numbers are still current." Of course it will depend on the year of your heads for the thread size. The above numbers are the 18mm thread. I've actually been able to get over 100,000kms out of a set of standard Autolite plugs in my Cougar and were only starting to get a little tired at that point. Speaking of Champions, how many people are using these? I haven't seen Champions up here since I worked at a Napa up here in the late '80's.
the plugs i am using are actual race plugs from the local speed shop.....and at $5 a plug....i am thinking twice about getting more of them.....
until you get a really, REALLY hot motor. Those plugs are overkill. A good set of platnums is good. I run 3924's in my 13.5to1 motor and they do just fine.
ok thanks...i wasnt too sure....but the speed shop said...they are hot plugs ..... i was actually leaning towards platinums at the time....
