If you are planing to rebuild a rotary engine , you should decide whether or not , you would be better off getting the engine rebuilt by a rotary expert , for example , if you don't know much about rotaries or you don't have tools or equipment to do the job then you probably will better off getting a rotary specialist to do the rebuild . Rebuilding the engine yourself will usually be cheaper than an expert to do the job but you might want to let someone else do the rebuild because it might be cheaper in the short term but it might end up costing more in the long run if you dont put the engine together properly . Remeber , Genuine Mazda rotary parts aren't all that cheap to buy . Here is a very brief summary on how to rebuild a first generation RX7 12A motor , also you I recommend that you mark every part of the engine that you take apart with a marking pen so that it will be much easier to reassemble when you know were everything goes . REMEMBER THAT THIS IS ONLY A VERY BASIC GUIDE THAT I HAVE WRITTEN MYSELF , SO I WOULD HIGHLY RECOMEND THAT YOU SEEK A PROPER FACTORY WORKSHOP MANUAL IF DO DECIDE TO DO THE REBUILD A MOTOR YOURSELF .
Disassembling the motor
You will need to do the following in order to disassemble the engine :
( 1 ) Remove the air pump and drive belt ( If equipped )
( 2 ) Remove the alternator .
( 3 ) Remove the carburetor and inlet manifold .
( 4 ) Remove the distributor
( 5 ) Remove the oil filter and cover .
( 6 ) Remove the water pump .
( 7 ) Remove the oil pan and oil strainer .
( 8 ) Remove the eccentric shaft pulley .
( 9 ) Remove the front cover .
( 10 ) Remove the oil pump and oil pump drive .
( 11 ) Remove the key , balance weight , thrust washer and needle bearing .
( 12 ) Remove the clutch cover and flywheel .
( 13 ) Remove the rear face plate .
( 14 ) Remove the rear rotor housing .
( 15 ) Remove the rear rotor .
( 16 ) Remove the itermediate face plate .
( 17 ) Remove the eccentric shaft .
( 18 ) Remove the front rotor housing .
( 19 ) Remove the front rotor .
Now that the motor is finally apart , it is a good time to clean all the parts and inspect all parts to see whether they need repairing or replacing . It is also a good idea to decide on PORTING the engine if you want to get more power out of it .When rebuilding an engine you should replace all seals , gaskets and bearings if you want your engine to go to its full potential .
Engine assembly
Start your engine assembly with the front rotor(It has the the letter "A" markd on it ) . Install new oil seal springs , oil seals and oil seal "O" rings . Repalce the apex seals without the springs and hold the apex seals in with a delicate rubberband ( Or suitable glue ) . Place new corner seal springs and corner seals only on the side of the internal gear . Mount the front face plate on a engine stand and place the front rotor on the plate . Lubricate the eccentric shaft with engine oil and insert the shaft being very careful not to damage the rotor bearing and main bearing . Before installing the front rotor housing , apply sealant to the front side of the rotor housing and put new "O" rings and new sealing rubbers . After installing the front rotor housing , apply engine oil to the tubular engine dowels and insert them through the front rotor housing holes into the front face pate . Now place the apex seal springs and apex seal side piece in their correct positions and remove the rubber band that is holding the seals in place . After inserting the apex seal springs , insert the corner seal springs and corner seals . Apply sealant to the rear side of the rotor housing and place new sealing rubbers and "O" rings . Remeber to lubricate the seals with engine oil . Pull the eccentrc shaft about 2.5cm and install the intermediate face plate through the eccentric shaft onto the front rotor housing . You will probably need the help of a friend to do this . Now after you have done that you can install the rear rotor ( Letter "B" marked on it )by following the procedure as was done to the front rotor . Install the rear rotor housing onto the intermediate face plate remembering to follow the same procedure as was done to the front rotor housing . After that is done , apply suffcient engine oil onto the stationary gear and main bearing , now install the rear face plate onto the rear rotor housing . Apply oil onto the the thread of the tension bolts and tighten the bolts in the order shown in the correct workshop manual . The tension of the bolts is also shown in the workshop manual . You can now turn eccentric shaft to see of every thing is working smooth . Apply engine oil to the oil seal on the rear face plate , fit the key to the eccentric shaft and then install the flywheel to the eccentric shaft . Apply sealant to both sides of flywheel lock washer and now install the nut . You will need to install a brake to hold the flywheel in place while you tighten the nut with a box wrench . Install the thrust plate , spacer and needle bearing onto the front of the eccentric shaft . Place the bearing housing on the front housing and tighten the bolts .Put the needle bearing and balance weight together with the trust washer onto the shaft . Install the oil pump onto the front face plate and fit the key onto the oil pump shaft . Fit the oil pump drive chain onto the oil pump sprocket and eccentric shaft and oil pump shaft , aligning the key and keyway . Slide the distributor drive gear onto the eccentric shaft with the letter "F" facing toward the front of the engine . Now you will need to adjust the eccentric shaft end play . Install the eccentric shaft pulley onto the shaft and tighten the attaching bolt to 72~87 ft-lb . Mount a dial indicator on the rear face plate so to contact the feeler with the flywheel . Move the flywheel backward and forwards and read the eccentric shaft end play . It should read 0.04mm - 0.09mm . If the end play is more than the limit , adjust it by grinding the spacer on the a surface plate using an emery paper or by replacing the spacer with a thinner one . If the end play is less than the limit then replace the spacer with a thicker spacer . After you have adjsuted to end play , you can put the front cover on by removing the eccentric shaft pulley , tighten the oil pump sprocket nut , check the oil pump drive chain slack ( it should have a limit of 12mm ) , place a new "O" ring on the oil passage of the front housing , place the gasket and front cover on the fron housing and tighten the attaching bolts , apply engine oil onto the oil seal in the front cover, install the eccentric shaft pulley onto the shaft and tighten the pulley bolt to 72~87 ft-lb and remember to use a new washer in the eccentric shaft pulley bolt . Now that the cover is finally put on you will need to put the oil strainer and oil pan on . Start with the oil strainer by putting it under the front face plate along with the oil strainer gasket . Apply gasket sealant to the surface where the oil pan will sit , now put the oil pan gasket on top of the gasket sealant . After making sure that there is nothing hanging over the edges , you can put some gasket sealant on top of the oil pan gasket and then put the oil pan on the engine . Install the water pump and tighten the nuts as shown in a factory workshop manual . From here on its all smooth sailing . Just install the oil filter and cover with the "O" rings , distributor , thermal reactor or extractor , inlet manifold and carburetor,alternator and air pump if equiped . Now finally your engine is put together . After installing the engine back into your car , you should refill the engine with oil and coolant and tune the engine . After you take the engine for a test drive , the oil should be replaced with new oil to clean out any foreign matter . You might think that this is a waste of oil but belive me it isn't . The next oil change should be in 1000km after the rebuild and then 5000km every time after that . The engine should not drink more than one litre of oil for every 5000km . By Paul Samulski
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