Assembly
Rotor Assembly
Assembly begins with the rotors. First, measure side seal clearances. This is done by placing a .0059” feeler gauge in the tapered edge of the side seal groove, along with the side seal. Then, with new corner seals in place, measure the gap between the corner seal and side seal. Technically this is to be the sum total of gap measured at each end, but you can slide the seal all the way to one side and measure from the other as well. Maximum side seal clearance should be .016”, but it’s recommended to keep clearances between .002”-.0059”.
Most vendors sell cut-to-length side seals, so you’ll need to grind your seals down with sandpaper and finish the ends with a whetstone. Its important that you keep the angle of the end of the side parallel with the corner seals to ensure a proper seal as the engine warms up. Here are several links to videos that explain this process in greater detail. Once a side seal is fitted to a pair of corner seals, be sure that they are installed in the same places as rotor side lengths are not perfectly equal.
- Great video on cutting side seals
- Some rebuilders have created special jigs for cutting side seals
- Another video explaining side seal cutting
Once side seals are fitted, remove them from the rotors. Insert new o-rings to the 4 inner and 4 outer oil control rings with a thick coat of petroleum jelly. For each rotor side, lay the rotor on a flat working surface. Using the table below, identify the correct oil ring spring for the rotor face you are working on. Place the rounded end of the spring face down and rotate until it catches in the appropriate rotation lock depression. This will help keep the oil control ring from rotating during operation. Then use the old oil control rings and a board to carefully press the new oil control ring into the appropriate groove on the rotor face. Once the oil control rings are installed, place the cut-off seal spring (pink side up) in the cut-off seal groove. Then place the cut-off seal in it’s groove, with the two ends meeting flush at the lock pin. Cover the cut-off seal with a coat of petroleum jelly.
Rotor | Front Rotor | Rear Rotor | ||
---|---|---|---|---|
Engine Front Side | Engine Rear Side | Engine Front Side | Engine Rear Side | |
Inner | White | Blue | White | Blue |
Outer | White + Pink | Blue + Pink | White + Pink | Blue + Pink |
Once the rings are assembled, for all four rotor faces, we can install the corner seals and side seals that were fitted earlier. Be sure the side seal spring ends are facing upwards, and the corner seal grooves are facing upwards towards the apex seal grooves. Also make sure that corner seals are installed with the large diameter end of the corner seal plugs are facing towards the rotor, otherwise they’ll come loose from the corner seals and interfere with the side housings. Finally, be sure to include a generous layer of petroleum jelly under all of these seals. The jelly acts as a combustible adhesive that helps keep the side and corner seals in the rotor assembly when placed back in the engine. Once those are in place, you can install the apex seals and apex seal springs. I would recommend using a rubber band to retain the apex seal springs while they’re waiting for installation. This will allow you to install the rotors without trying to install the apex seal springs afterwards. Include a generous coat of petroleum jelly on the exterior of all seal surfaces, and coat the inside diameter of the rotor bearing with assembly lubricant. The rotor assembly is complete and ready for installation.
Rotor Housing Preparation
Before assembling the engine, water jacket and engine seals must be installed in the rotor housings. This is different from previous rotary engines, where they were installed in the side housings. Before installation, be sure the rotor housings are clean and free of debris which may impair installation or damage the engine during operation. Lay each rotor housing face flat on a clean work surface. Lay a bead of petroleum jelly into the grooves for the inner and outer rotor housing o-rings. Again this will keep these components in place during assembly. Then install the rotor housing o-rings into their corresponding grooves. The white paint on the outer o-ring must not be showing, and the inner seal joint should be between the 10 o’clock and 12 o’clock positions (pictured). As a side note, some rebuilders will use hylomar instead of petroleum jelly for the rotor housing o-rings. I haven’t tried this, but can confirm that petroleum jelly is capable of working without issue. Install the dowel o-rings on the top portion of the rotor housing and seal with hylomar. Finally, coat the inside of the rotor housing with a thin coat of petroleum jelly or assembly lubricant.
Engine Assembly
At last, the engine components are ready for assembly. Start by bolting the front stationary gear to the front side housing and the rear stationary gear to the rear side housing, and lubricating the gears and bearings of both. Then mount the front housing to the engine stand. Then slide lubricated dowels into the appropriate bore on the front housing. Place a bead of silicone sealant on the areas of the rotor housing indicated (see picture) and slide the rotor housing over the dowels and onto the front housing. At this point, the silicone sealant will start to dry and assembly needs to be completed before that drying occurs. Place a coat of assembly lubricant on the face of the front housing. Place the front rotor inside the front rotor housing (gear side facing down). Be sure that all seals in both the housings and the rotors are in place as they are installed. Then slide the eccentric shaft into the front rotor and front main bearing, and rotate slightly to remove any tension.
Before installing the intermediate housing, apply a coat of assembly lubricant on the rearward face of the front rotor, and a bead of silicone sealant to the same areas as the other side of the rotor housing. Then lift the eccentric shaft a few inches vertically and angle the inner bore of the intermediate housing over the rear rotor journal of the eccentric shaft. Align the intermediate housing with the dowel pins and lay flat against the front rotor housing. Installation of the rear rotor and rotor housing is the same as the front, with the exception of placing the rear rotor over the eccentric shaft during installation. Then install the rear side housing. Lubricate the tension bolts and install washers on all except the bottom bolt on the exhaust side of the engine. The three indented bolts are to be installed as shown. Torque to 23-29 ft-lb in two three passes in the sequence shown. It’s also recommended to rotate the engine using the flywheel nut to keep any parts from binding.
Great, now the short block is assembled. Before putting everything back together, we must check eccentric shaft end play. Using the locking tool, install the flywheel and torque to 289-361 ft-lbs. Then rotate the engine so that the front is facing upwards and install the following in this order.
- Spacer
- Needle Bearing
- Thrust Plate
- Eccentric Shaft Key
- Balance Weight
- Oil Pump Drive Gear
- Oil Metering Pump Drive Gear
- Pulley Boss
- Eccentric Shaft Position Plate
- Eccentric Shaft Pulley
Apply engine oil to the pulley boss lockbolt and torque to 222-250 ft-lb. Then use a dial indicator to measure eccentric shaft end play. If it exceeds .0016”-.0035” replace the spacer with a thinner version. If less than .0016” use a thicker spacer. Spacer types are detailed in the table below. If this is within specifications, remove the pulley components and oil pump drive gears and resume assembly.
Install the oil pump as it was removed, with the chain over the drive gear and the sprocket. Torque the oil pump sprocket nut to 23.2-34 ft-lb and bend the lock washer up against the side of the nut. Place the oil metering pump drive gear on top of the oil pump drive gear. Install the front cover, ensuring proper alignment between oil metering pump gears. This cover requires a gasket, and bolts should be torqued in the order shown to 13.8-18.8 ft-lb. This will require the water pump to be installed at the same time, also torqued to 13.8-18.8 ft-lb.
Reinstall the pulley boss. Place the oil control spring and bypass valve back into the eccentric shaft as they were removed. Apply engine oil to pulley boss lockbolt threads and a layer of silicone sealant to the face of the pulley boss lock bolt. Install and tighten to 222-250 ft-lb. After this, flip the engine upside down and apply a layer of silicone sealant (as pictured) to the oil pan. Place the oil pan on the engine and torque bolts to 13.8-18.8 ft-lb. Finally, complete reassembly by installing remaining components in the reverse order of removal.