Part of the allure of building an engine is the challenge you find within the smallest details. Checking parts down to the thousandth of an inch is part and parcel to making reliable horsepower. While most of us have no trouble putting a short-block together, we stumble when it comes to the cylinder heads. Typically, we'll buy a new set of heads and assume that because they are new, they must be correct. Nothing could be further from the truth in some cases. And it's up to you to find and correct the problems before they cause damage or cost you power.
We've found several tips for making reliable power and helping to make the task of checking the heads a bit easier. There are also some trick performance parts we found that will make your heads last a whole lot longer. So copy and laminate these pages, then put them in your toolbox for easy reference any time you are playing head games.
Spark Plug Depth
With so many different heads on the market today it's important to be sure you're matching the right components to your particular set. Most head manufacturers take the time to carefully test that particular spark plugs will work. They usually list specific spark plug part numbers in the instruction sheet that comes with the heads. If you want to run different plugs than those they recommend, be sure to get plugs with an equal "reach." That way, the correct amount of the spark plug will protrude into the combustion chamber. Too much or too little can cause problems, and the pistons may even hit the plugs if they're way too long.
Pictured here are two Autolite plugs in a Dart Pro 1 head. On the left is a plug that's too short, and on the right is one that is the perfect length. The plug on the right is known as a Surface Gap plug and features no ground strap to speak of. Rather, the spark has four distinct points to jump to, creating a more reliable arc even under extreme cylinder conditions. Also remember to apply anti-seize to the first set of plugs you install in your aluminum heads and follow up with a light coating of anti-sieze on every other set of plugs you install. Too much anti-seize can cause detonation in the chambers, so never apply it past the end of the threads.
Color Me Perfect
If you've recently purchased a cc'ing kit to measure your chambers and ports, there's a clearer way to see your fluid. Most cc'ing experts agree that ordinary rubbing alcohol is the best fluid to use because it completely evaporates. But alcohol is hard to see, and most guys simply add food coloring to it. Buying your rubbing alcohol already dyed mint green is an easier way. This stuff is normally sold to people that use it to sterilize their mouths, but it's only a few cents more a bottle and is easy to see. Besides, it smells nice too.
Suck It Up
After you're done cc'ing your heads with your new mint green alcohol, use a Mighty-Vac hand vacuum pump to get all the alcohol back out of the chamber. You simply attach a narrow tube extension to the hose and suck it into the plastic collection can that comes with the Mighty-Vac pumps. This is also a good way to double-check your measurement because you can pour the alcohol right back into the burret and see if it refills very close to the top. You can also use the Mighty-Vac pump to remove some alcohol from your burret if you over-fill it.
Not all spring heights are created equal. Most of the time installing new valve springs is a simple process. But if you're gong to run a cam with more lift it's wise to increase your spring's installed height. The easiest way to measure spring height is with a mic like the one you see here. But you can also use a snap-gauge and micrometer. Installing or removing shims under the spring creates equal heights for every spring. Also, if you're using multiple shims, always run the thickest shim in contact with the spring. Springs can cut through thin shims, and if there's no shim or steel cup under it, the spring will gouge aluminum cylinder heads and ruin them in no time.
Teflon PC seals are the most widely used type of valve stem seal on the market today. Installing new PC seals can be a real pain in the neck without the right tool. This seal installer from Powerhouse is designed to surround the seal as you simply push it on. Information: Powerhouse Products, 3402 Democrat Rd., Dept. SC, Memphis, TN 38118, (800) 872-7223, www.powerhouseproducts.com.