Just a quick note if anyone can tell me a good set of plugs to run in my 1963/340hp 327? A set that you may have used and have proven to be reliable please, not just a quess like someone gave me over here LOL! He was wrong DOH!! NGK is a brand i can get easily but i may be able to track down the AC delco's if i look hard enough. All my books are at a freinds so i can't research it myself at the moment.
A Champion equivalent is J12YC or J14YC..the 'C' at the end means copper...It wont perform any worse or better than any other plug. You may need a conversion to cross reference different brands to get the proper heat range to match a AC #45 or R45.heat range.....there are no 44`s and do not use a #43 range plug for crusing, that plug is better suited for racing
The high compression piston of your 327/340 has a .125 dome. If you have the correct 461 heads, the spark plug location is lower than with later 462 heads, later GM heads, or aftermarket heads. The close proximity of the spark plug with the piston dome requires a standard gap plug and not an extended gap plus such as the "S" suffix AC plug.
I've tried the extended gap plugs in my L76 engine (same piston and 461 heads as the '63 327/340) and it worked poorly compared to the standard gap plugs such as the AC R43 or R44, or the Champion J-6 plugs.
I also use NGK spark plugs on my Corvette and other car except on my Porsche 911.On The 911 i use Bosch spark plugs.The 911 have a tendensy to eat sparkplugs when not driven hard.Had some people doing some work in my driveway and had to move the car and in the end it was changing sparkplugs again.
I think the NGK plugs are working great but every Porsche shop advice against using other than Bosch spark plugs on Porsches here in Norway. Dont know why.
Any one that fouls out a AC 45 heat range plug has something wrong...Plugs are the only thing that will give you a insight into the engine..by reading the plugs it will help locating the problem...But its not the plugs if your within the proper heat range regardless of the brand. ....they all start out at the same temperture and that's a fact......
What i was told by the mecanichs is that the sparkplugs does not hold when just moving the car for some yards a day wich i did this spring having some here doing some work so i had to move my cars.
Never had any problems with any other car when just ,lets say short driving.
I use Denso W14-U..... They are a non resistor plug like the original plugs that came in our cars. Same heat range as the AC 45R......I order them from Rock Auto. If you have any kind of transistor/electronic ignition, you might want to stay with resistor type plugs.