In this article I would like to explain how I adjust valves. Why am I writing an article on this? This is air cooled VW 101 people; and I find a lot of people just don’t know how to or don’t want to be bothered with it. Understand that on these flat four motors we have a long push rod and when you heat any metal it tends to expand. Our motors expand more than most other types of engines and keeping the valve clearance is important for the efficiency of the engine. By now you’re probably saying “Aww I don’t need to read this, I already know how”. Well read it anyway, it might save you some time. If you feel the way you do it is better then great, but this is what works well for me.
First thing is that the motor has to be cold - Same temp as the outside air. Gather up your tools. You’ll need a large screwdriver to undo the valve cover bail, a 13mm box end wrench, a medium size flat blade screw driver, a set of feeler gauges (.006 being the one for most engines), and a 30mm wrench or a large crescent wrench to turn the motor over. It’s not a bad idea to have two fresh valve cover gaskets on hand. For a street car, it’s also not a bad idea to either have the ass end on ramps or jacked up to make getting to the valve covers easier.
First thing to do is to pop the cap on the distributer. This is to ensure we are on number one. Keep in mind, the crank goes around twice for every time the cam goes around once. So turn the engine over with your wrench until the TDC mark on the pulley is at the seam of the two case halves. Look at your rotor, is it pointing at number one wire or number three? If you’re not sure, set the cap back on and follow the wire that the rotor is pointing to that cylinder. The layout of the cylinders is marked on the cylinder tin, but just in case it is as follows. Number one is on the passenger side towards the front of the car. Number two is also on the passenger side towards the rear of the car. Number three is drivers side towards the front of the car. Number four is drivers side towards the rear of the car. Now I could tell you how the rotor should be pointing in relationship to the car, but man have I seen so many distributors in backwards or in the oddest rotations you can imagine. So just follow your wire. Once you are sure your rotor is pointing towards number one, lay down piece of cardboard to lay on under the passenger side. With your big screw driver, pry down the valve cover bail. Note: some of you I am sure have bolt on valve covers. If so, do what you do to get the cover off. Now what I do is grab the rocker up by the valve and just move it in and out to see if I have any play on both the intake and the exhaust on that cylinder. If you do, then take your feeler gauge and slide it between the adjusting screw and the valve stem. I find if you use a slicing motion it tends to go in the gap better. Do you have a drag on the gauge? If so you’re good. If it falls in then you will need to tighten it. If you can’t get it in then it’s too tight and you need to back it off. “I am not sure what you mean by drag on the gauge?” Well, it’s a little hard to explain in words. It’s a feel thing. If you’re not sure you’re setting them right then go up one size. If you can get it in there then you’re setting them too loose. Do both the intake and the exhaust for that cylinder. While you're there looking at your rocker, look at your hair pin clips and washers that hold the rockers to the shaft. Are they all ok? Do you see any broken spring washers? If you have solid shaft rockers (after market) make sure the end caps are tight. Now that we have adjusted number one it’s time to move on to the next. Here if my trick. I rotate the motor backwards, counter clockwise. Turn the motor 180 degrees. So if you have a stock pulley then it’s a guess on BDC. Look at your distributor cap and make sure you're pointing to number two cylinder. Get back under the passenger side and check number two cylinder valve gap. Once you’re done there put your valve cover back on. Then back up top and rotate the engine again backwards to number three cylinder. Pop the drivers side cover off and adjust that cylinder. Back up top and rotate backwards again to number 4 cylinder. Once done put that cover back on. Back up top for the last time. Put your distributor cap back on with its clips. Clean up your mess, you’re done.
More than anything here, you’re checking them. If your motor is new then as I stated in the last article you will need to check them a lot until everything finds a home. As a general rule, you should be checking them every three thousand miles. Personally, I check them more in the summer time then I do in the winter because the motor runs hotter in the summer. The adjustment or gap will vary depending on what rockers you have, what pushrods you run, etc, but for most daily drivers it’s .006 with a stock style rocker and aluminum push rod. If you’re not sure, check with who built your motor and ask them what they want you to set the valves at.
I hope this helped. Rock on.