Hot or cold plugs?

[mcditalia]

For a 327/350hp motor should I be running AC43 or AC43S plugs? I believe the differences are in the heat range. Zip catalog says 43. I am currently running 43S. Original specs call for AC44 which I'm thinking they aren't made anymore as nobody lists them.

MC

 

[BLACK MOON]

Never heard of the 43S but with the 327/350 I'd suggest the 45's. You really need to see how they're performing first. Mostly short trips around town use a hotter plug. Long drives/ highway use use the stock recommended plug. Just my opinion.

 

[iron cross]

R43`s are too cold. The "S" means extended tip. Not recommended for high compression engines but ok for the lower HP cars. Buy a set of R45S and the engine should clean right up. 44`s in any style have been discontinued and the 45 is a better replacement choice.