OK, so I found in the RX-7 competition prep manual (Toyo Kogyo) that the ratio should be 1:100 - 1:150 using low ash content mineral oil (not synthetic) of 40w or 10w-40w. However, what I can't find is if I need to change the jets in the carburator to compensate for the leaner fuel/air mixture. How do I determine, without an exhaust gas analyzer, what I need to change the jets to so that I can compensate for premix?

Has anyone done the premix test yet?

What would be the diffrence for FI? or would the same apply?

It has been a long time since I've read through all five pages of this post, but I think several people on this forum are using premix instead of using the factory Mazda installed oil metering system. I don't think anyone who daily drives their RX-7 is running that much oil to gas; I recall reading 1:300 which would work out to about 6 oz of oil for a 14 gallon fill up.
Racing beat has a pretty good summary of the system at racingbeat.com/mazda/performance/rotary-tech-tips/oil-filters-mop.html (mid way down the page). Looks like they describe what works out to approx 1:180 for 89+ models and even more for super high HP builds for racing.

I personally use the factory metering system and I change my oil way before it gets dirty. I also add Rislone Oil Supplement with Zinc/ZDDP Treatment during my oil changes.

Never used it, but just tossing it out there. Saw it in a catalog at work once.

Rotary pre-mix oil: http://www.idemitsu-usa.com/page_210.htm



~T.J.

I got a gallon jug of 30W 2 cycle oil. I throw several ounces in before every fill up with no problems. I do this because I have not gotten around to fixing whatever is keeping it from burning any oil.

~Spike~

I have a 1980 RX7. My understanding is that 2 stroke mix is better than no lubrication, when the Oil Metering Pump is not working properly. Until the engine of my car is rebuilt, with the carb and oil metering pump working as they should, 2 stroke mix is being used. The car currently has a bit too much oil in the mix but it better than not enough.

I pre-mix. Not so much for doubt of the OMP or any other reason; just because I like going to the gas station and pouring oil in my gas tank. Makes the car even stranger. :D


But I just recently had an engine apart, and I looked at the front cover design. It looked like the OMP really wasn't so much as a pump but a metering device. Its feed by the oil pressure (powered by the oil pump). Then the oil goes into the OMP and the OMP merely lifts the pressurized oil feed into the tubes. Failure, aside from clogging of the tubes, is really hard to imagine. Unless your oil pump goes out; if that's the case no oil to the rotors is the least of your worries.

^^Am I right in this thought process? I'm just going by what I looked at.


Really clever design. I can't wait to rebuild my 12A with a working OMP. But I might throw in an ounce of oil during fill ups, with that car, just for old time sake. ;)