spark plug heat range

[Alaska Jim]

I bought some new plugs the other day. Autolite 45's and 46's. am I correct in that the 46's are a hotter heat range than the 45's? if so what would the # be for 1 heat range colder than the 45's? I should know this, but for some reason just can't remember. any help would be appreciated. Thanks, ---Jim

 

[TedEaton]

The 46's are hotter than the 45's. I typically run the 45's in most street Y builds. If the engine is extremely low in compression or is pushing a nominal amount of oil up past the rings, then 46's would fit the bill.

 

[Alaska Jim]

Thanks Ted, I thought that the 45's were correct. my eng. is new rebuild. and I am soon going to put the tri-power into working order and wanted a few different heat ranges on hand to play with.------Jim

 

[Motorhead6]

44 down to 42. If you don't have detonation, opt for the 45s.