If you love Mazda rotary engines and make that emotional decision to buy a classic car like an RX-7 or even a more prized model such as an RX-3 or R100, it’s not long before you start thinking about a rotary rebuild and modifying the engine to give it more power or noise, or if it is a stock engine, keeping it in the original shape.

While the life expectancy of a rotary engine varies depending on the usage and care it gets, it is accepted that a rotary engine rebuild will occur more frequently to a similar piston engine. However, unlike a piston engine that can be dismantled in part while it is still installed in the engine bay, a rotary engine needs removal from the car to do any internal inspection.

Because these engines are quite easy to work on, many enthusiasts have pulled them apart and reassembled them and found they will still go! This has often given these people a false sense of security that they know what is what when things couldn’t be farther from the truth.

A rotary rebuild is a very technical and methodical process where many of the parts that are going to be reused require specific cleaning and polishing, the rotors in particular need precision balancing to eliminate vibrations and exact fitting of the side and apex seals.

If any porting is to take place, this must be done with the utmost care to ensure that: junkyards near me

The flow volume across all the ports is the same, uneven port flow causes incorrect temperature distribution due to varying combustion temperatures, one rotor housing could be very hot due to a leaner mixture entering the chamber, while the other housing could be operating much cooler due to too much fuel mixture for the amount of oxygen. This rich running can also cause excessive backfiring and detonation issues damaging the motor.

The exhaust ports must also have precise modifications to ensure the gases leaving the combustion chamber are doing so in a controlled fashion and not escaping into the next intake of fuel and air.

It is quite common for enthusiasts and ‘backyard’ operators to try to skimp on parts costs, therefore reusing items that should be thrown away after the engine strip down. These include worn rubber seals and gaskets, bearings with play in them, even old rotor side and apex seals. Saving a few cents here and there usually results in a much more expensive problem later.

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