Mach 1 Club

I have been told that is is a good idea to run a hotter plug in a 351 4v. What are your thoughts on this, remember I reside in Minnesota.

While a couple of heat ranges up probably won't hurt. It's best to read the plugs and see what the engine needs. There have been a ton of articles on this subject in Hot Rod and almost all auto magazines. You should be able to type in, how to read spark plugs in your search bar and get a bunch of choices. If all else fails, Pull 2 plugs on each side of the engine, usually not next to each other and the easiest to get to. Now look at the insulator, the white ceramic part around the center electrode. It should be a light tan or grayish color. That indicates a proper air fuel ratio , all is good. If the whole plug is black and sooty you're to rich, If the plug is bright white or blistering then that its to lean. Compare it to the other 3 plugs they should all look similar, if not you may have a vacumn leak on that cyclinder, which will cause the bright white blistered look. People that want to go to a hotter plug are usually tring to compensate for an over rich condition. Usually to big a Holley, with to big a jets, with a cam. You see where I'm going? Mismatched cobbled together, and they're trying to make it run. So they stick a hotter plug in it. Hoping that will magically cure everything. In actuallity, Its nothing more then a band aid. Usually the factory plug is more then adequate. Even if you've modified your car and matched the components fairly well you shouldn't have to much problem. With the stock heat range. JTS 71 Mach1

JTS71mach1: Hits it on the nose on this one.
Its basically a good plug chop that motorcycle guys use when calibrating for altitude changes and carb jetting changes.

I always use the standard plugs and the "proper jetting" will go a long way in my humble opinion.