Yes you can take all the plugs out or you can take only one out yes having the carburetor held wide open during this test will in effect give you a more accurate result. The old style starters don't crank as fast therefore people like to take all the plugs out AKA rid the resistance. Don't worry about the cranky people. As mentioned.. around 145lbs is what you expect from a bone stock 318 / rebuild, slant 6, 360 etc.. 8.1 or about. If you have less than that... we will need to look into the 'why' . Someone was mentioning stock cam or RV cam or something like that but I'm not thinking you have an RV cam for some reason not after all the money you put into it. To stick a white box cam in there would be pretty half-***