Re: Spark Plugs

Posted by Owen_Dyneto On 2012/5/19 17:24:08

I'll leave it to others more knowledgeable than I about the particulars of the cylinder heads.

But to address your #3; YES! heat ranges of plugs should be of importance to you, very much so. Too cold a plug will quickly carbon up, foul, and fail to perform properly, engine missing being the most likely outcome. Too hot a plug will lead to preignition and probably self-destruction of the porcelain insulator. Once you determine which reach plugs are correct for you, you can get advice on which plugs perform best for your car from others on the site, or just go the AutoLite website, find their sparkplug recommendation and lookup chart, and select accordingly. You'll have several satisfactory plugs to chose from, though not necessarily the same make and number as was originally supplied. I've had 3 or 4 different plugs in my 56 with good results, but they are all of the proper heat range.

Pulling a spark plug after a few hundred miles of driving and just making a visual examination of what you see should tell you whether the heat range is reasonable. Look at the inner porcelain sleeve surrounding the center electrode; you want to see very light tan to nearly white. Darker or sooty is too cold, too hot is a bit harder to spot but the porcelain may be scorched hot (extremely white), perhaps cracked, and the electrode wear will be advanced.