This is the EBMods Engine Head Clearance Gauge. The EBMods Head clearance gauge allows you to accurately check the head clearance on your engine, so you can adjust your deck height for optimum performance. This dial indicator can also be used to check for rod stretch, excessive wear on the crank pin, wrist pin, rod bushings, and piston fatigue. Includes an aluminum block that is used as a flat surface to complete your measurements, and an EBMods Break In Sleeve to use as a soft storage container.
Its recommended that you always measure your head clearance after the engine is broken in and find your zero before you adjust the clearance. You will also use this number as a baseline measurement when checking for crank pin, wrist pin, rod bushing, and piston wear.
First, you must 0 the gauge to your head button. Start by removing the glow plug and turn the engine until it hits Top Dead Center (TDC). Once you have the engine at TDC, insert the gauge. Rock the indicator back and forth going front to back and then side to side, just a little at a time. Take notice, the indicator needle will move left and right, and at one point the needle will stop and change direction, this high spot is your 0 position.
Now turn the indicator face to 0 and lock the face in position. Recheck your measurement and adjust the face so you can repeat this number several times.
Now remove your head button completely from your engine, and place the head button on the flat aluminum block. Insert the gauge and do the rock method again to see your high number. This number is your head clearance, which is the clearance between the piston top and squish band area of the head button. You can also reverse this process and zero with the head button on the flat surface, and then check the engine clearance at TDC and read your high number with the engine together.
To check for rod stretch, and other worn parts you must first have a measurement of your head clearance at TDC. You can then turn the engine until it reaches TDC, and read the number. If the clearance has decreased from your original measurement then the rod has stretched. If the number has increased then either the rod bushing, crank pin, piston boss, or engine bearing have issues.