[rx4ur7]

What I see is a pair of good elastic band pants with a belt and suspenders added when the body now has a 4 in smaller waist. I concur with your machinist, as would any of the top builders I would imagine.

Mazda hasn’t changed the setup on the front cover and oil pumps since the 60’s. Other than bigger pumps and the double o’ring setup.

I commend you for your time and effort though. If this was the first run of the development motor and there were oil pressure leak issues at the pump I am sure it would have been in the testing stage. Isn’t the cost of a new oil pump cheaper than the mod on a questionable or damaged used?

Lack of low rpm oil pressure is mainly due to worn out bearings. Scored oil pumps will also add to that symptom.

Believe the main reason you have higher pressures is the installation of two shims in the valve.

The front housing comes with a machined surface where there is no gasket or oring required. I think I see some frisky cleaning. I would imagine if you measured the surface it might not meet Mazda’s machine surface specifications. There really is no reason to use any abrasives on any of the machined sealing surfaces in the Rotary. To due can induce problems. When I went to school it was “Never use sandpaper to clean these surfaces!” If it is damaged or out of spec, replace.

A new oil pump in a motor with new bearings and good eccentric shaft will produce plenty of idle oil pressure. Motors built here produce 120 psi at speed and ~35 psi at idle, depending on weight of oil. New pump, new bearings, and 1 shim. Never had any oil issues in any motor built, even in those that were built with used pumps, non-scored.

For you all with older pumps 72-82 you can install the impeller sets from the 83-85 pump. As long as the body is not damaged or scored you can go that route otherwise go new or if you have to get the comp pump.

You could possibly have problems with your oil cans. Mazda filters never failed in any of the race or street cars stock or with modified oil systems. The 792P used factory oil filters same the one used on street rotaries, never had an oil issue.

I would put money and effort into a new oil pump and chain. And/or a good set of stainless lines, very nice work there. New bearings when you do the motor. If you build it right the first time odds are you are not going to have to worry about it again.

Just my opinion and thoughts after nearly 40 years building these puppies. I am a firm believer in both If it ain’t broke and KISS philosophies. Why reinvent the wheel/rotor.

GT3 as shown with the 12A Bridge choked to 34mm in the 48IDA would peg the 120psi gauge cold, during a race wouldn’t go below 100. Stock Mazda oil pump and filter. Never had an oil issue in all the years run. Car would always finish unless the nut holding the steering wheel did something wrong. None of the IT cars ever had any oiling problems either.

Oil system mods beside shim port and polish oil passages in front housing, match port oil filter tower and clean up oil filter tower passages.

Race cars are black holes – What is the quickest way to become a millionaire in racing? Start with two.