CLEANING: Thoroughly clean all internal components and the housing with brake cleaner, and dry before proceeding.
INSTALL ROTORS: If the outer rotor has a "pip" mark on the top of the surface matching the inner rotor, then it must be installed so the "pip" is facing the cover just like the inner rotor does. Do not install the relief valve until the final assembly
CHECK FOR UNIFORM ROTOR HEIGHTS: Make sure the inner and outer rotor are the same heights. If not, machine or sand the taller piece down to match in height. When finished, re-polish to a mirror like lustre.
CHECK HEADSPACE: Slide cover plate off to the side just enough to slip a feeler gauge in-between the rotors and cover plate. Use heavy finger pressure at the very outer edges of the cover to hold the plate down and use just slight pressure to insert the proper feeler gauge to measure headspace. This is the clearance between the top of the rotors and the bottom surface of the cover plate.
THE RIGHT AMOUNT OF CLEARANCE: The right amount of headspace clearance between the top of the rotors and the bottom of the cover plate should be no less than .002" and no more than .003". Too little clearance can result in binding between the rotors and cover plate when hot and the metal expands, where if the oil pump does not sieze, premature distributor/oil pump drive shaft failures may occur. Too much clearance will allow excess oil to leak by resulting in loss of oil pressure and volume.
ADJUST HEADSPACE: In most cases there will be too much space between the cover plate and the tops of the rotors, resulting in a loss of pressure and volume from escaping oil between the excess space. To reduce the clearance, remove the rotors and evenly remove metal from the housing surface where the cover bolts to with a fine toothed flat draw file. Periodically clean and reassemble to check the headspace clearance. If there is too little clearance, you will need to sand both rotors evenly to reduce their height and increase the assembled headspace clearance. Make sure you remove metal evenly all around in either case. The height consistency can be checked around the rotors with a dial caliper, or using the depth feature by checking the cover plate surface to the depth recess of the housing in different places on the outer edge. Sometimes the housing will be slightly deepeer on one side than the other. Remember, .001" is all it takes if you truly want the precision a successful blueprinting requires. Using the feeler gauge method as illustrated above and by inserting it under all 4 corners of the cover plate, you can fine tune and adjust this unevenness by filing hard on that side than the other.
FINAL CHECK: After disassembling & cleaning all the internal and external components for a final time, install internal components into the housing and re-check the headspace clearance using the feeler gauge method as previously described. Then, while not required, it is recommended to do a final assembled clearance measurement with the cover torqued down.
DIAL INDICATOR: With the oil pump assembly installed and bolted together, using a clamp-on or magnetic base stand and a dial indicator, mount the indicator so you are measuring perfectly inline with the oil pump's input shaft. Press inward on the shaft and set the dial indicator to "zero". Then with a needle nose pliers, carefully grab the input shaft without disturbing the dial indicator and pull upwards. Read the measurement shown on the dial, it should not be less than .002" and no more than .003" movement. The oil pump to the right is purposely set to the tight side of .00175" (one and the quarter thousandths of an inch) for the ultimate maximum oil pressure and flow potential. Sometimes you will get a different measurement with the dial indicator than from the feeler gauge method since the cover is torqued and covering the entire rotor surface, as well as not being able to pull up as hard with a needle nose pliers as compared to inserting a tighter fitting feeler gauge.