Typical fuel pressures would be 2 1/2 to 3 1/2 pounds at the carb inlet. A fuel pressure isolator can be used to carry fuel pressure to a gage in the cabin. So the gage is powered by a few table spoons full of antifreeze, should a gage fail. Or an electric gage.

 

Racers use these carbs well above their design flow rates. It is a common problem to find that the fuel flow is so high that the little filter element under the brass nut adjacent to the fuel inlet banjo fitting has become the main jet. It is also so fine a mesh that anything in the fuel will plug it up. Remove and discard this filter. Install a big in line disposable filter can next to the carb or at least close by. The fitting out of this filter can have a Tee fitting to provide a fuel pressure reading. The gage should be in the leg of the Tee not the run.

 

I run two Carter 7 PSI rotary vane pumps in Parallel to maintain 6 PSI at the end of the longest straightaway. Great pumps. Last 3 years in a a racer. I give them away when the output drops to 6 PSI. 

 

This pump puts out a bunch of fuel. It is internally regulated, but I regulate it to 6 PSI right at the carb.

 We use just one pump until on the pace lap and well up to speed. Then switch on the second pump.

 

Pumps in Parallel double volume capacity. Pumps in series will double the pressure. 

 

The downside of a positive displacement pump is that you cannot suck fuel through them or blow fuel through them. So a back up pump needs to be in parallel with the main pump.

 

I suspect that the gravity feed provides enough fuel for the RPM max you have now but there is little to no fuel level in the bowl to support the boosters (auxiliary venturis). The idle jets and transition circuit is a few small holes right beside the down side of the butterfly.

 

With the pump turned on for a few seconds let the fuel pressure come up to 3 pounds minimum. Shut off everything. Take the bowl cover off. Look at the fuel level, with the float pushed down to the correct height. Or just forget it if you get the revs you need with the prop back on it.

 

Do not use the old style timing light. If you have stents or a pace maker or a defibrilator you can kill yourself with it. Inductive only. Try flipping the pickup over to reverse the polarity. If that doesn't work reverse the two leading wires. They both fire at the same time anyway so where the pickup is attached is of no importance.

 

The trailing plugs are distributed. They cannot be fired at the same time because one or the other will have an apex seal between the plugs exposing the next fuel charge to the spark 100 degrees too soon.

 

For years the stock maximum oil pressure in every Mazda rotary was 71 PSI. Probably checked at 3,000 RPM. The shop manual would have the exact measurement. For an unloaded engine very little pressure is required. The bearings are well oversized for the stress involved. By 3,500 RPM you should have at least 71 PSI. In the racer I run 100 PSI. The FD twin turbo runs 115 pounds, and the Renesis has over 100 PSI at it turns up to 9,000 RPM. Not required in an airplane. The oil pressure relief valve is in the bottom of the rear iron. You can change it out for a different model with the oil pan off. Later pieces are welded shut, and difficult to alter. Early pieces in the RX-2 RX-3 and RX-4 can be disassembled and washers installed to give any pressure you like. I would like 80 PSI at full tilt. We raced on that for years and never lost a bearing. But 71 is fine since the airplane use is far below the stress of even hard street use. You could install the later relief valve but the added pressure is not needed and the pump will wear out sooner.

 

Not to worry.

 

Lynn E. Hanover