Simmonds 530 Fuel Metering System - IO-360-B1A

[jliltd]

I have a friend that just purchased an RV-4 with a high-compression 200hp IO-360-B1A. It is a wide-deck parallel valve engine that the original builder put 9.5:1 compression pistons in. It has Bendix shower of sparks mag system kind of like a Piper. This seems like a fairly rare engine as it is the only 4-cylinder engine that the Lycoming factory made that forewent the Bendix injection system for the Simmonds injection system. Apparently this model of engine was used in Lake Amphibians, Seabees and Beech Travelair twins with it's stock compression yielding 180hp.

I was a bit perplexed the first time I saw it as it has an accelerator pump on the throttle body and uses a constant-flow fuel pump upon which there is a mixture control and vapor/fuel bypass vent return line. This fuel pump is mounted on the accessory case. The second component is the throttle body, mounted on the bottom of the sump for vertical intake, per it's stock IO-360-B1A configuration. The last item is the flow divider "spider" which, unlike most other fuel injection systems, is mounted below the cylinders just aft of the throttle body. So the 4 steel injector lines route up from below the cylinders up to each cylinder through the aluminum baffles. Looks weird not seeing the spider with it's legs on top of the engine.

From what little I've been able to find on the system it appears to use the same starting procedure, hot or cold (which in Lycoming's operators manual for Simmonds-equipped engines calls for accelerator pump priming). With the spider being on the bottom of the engine (i.e. not "baking" when parked hot) and the constant-flow fuel pump allowing cool fuel to route through the lines when the electric boost pump is turned on helping to purge any vapor from the system it seems less prone to vapor lock / hot start issues. Seems kind of neat.

Needless to say my old standby Lycoming "hot start" procedure has gone out the window. This is like a whole different engine with this Simmonds brand injection.

I have also noticed that the ECI fuel injection system seems to use the same type of 3-component design and constant-flow pump as the old Simmonds. Does anybody know if the ECI and/or Simmonds have any heritage with each other?

With the above being said there is a peculiar set-up on this specific airplane. The cowl has the cold-air inlet bulge on the bottom and it has been set up for full-time ram air without filtration. Inspection shows that at one time there was an airbox bypass that used filtered air from inside the cowl and a butterfly door would swap between ram air and filtered air kind of like an "alternate air" set-up. Now a previous owner has removed the push pull cable and riveted the bypass door shut yielding the current unfiltered ram-air only configuration.

I find this intake issue unacceptable. Especially since we live in a dry desert area where sand storms are common. No carborundum in the engine for my friend, thank you very much. I want filtration.

There also seemed to be an anomaly on the delivery flight back home. If the electric boost pump was left on during roll-out or taxi the engine would quit. Pump off worked just fine. I am not sure if the electric fuel pump should be turned on for takeoff and landing with a Simmonds system due to this behaviour. Common sense says that electric pumps should always be "on" during those critical phases of flight. But at the risk of the engine stopping?

Has anybody set up a Simmonds system with the standard lower cowl scoop and vertical intake sump configuration? This engine with it's injection system seems fairly obscure.

I know this was a lot of information but it seems every time I've think I've seen it all something like this Simmonds thing shows up and reminds me how much more I need to learn about piston aircraft engines.

Thanks,

Jim

[rocketbob]

Its been a lot of years since I've seen a Simmonds but as I recall you don't use the boost pump, like a Continental.

[Kevin Horton]

I found AFMs for Beech Travelair D95 and E95 in our library at work. Both models have Lycoming IO-360-B1A engines. The fuel system description says that electric auxiliary fuel pumps are fitted between the tank selector valves and the engines. The aux pumps are to be used for starting and emergencies, and may be used for take-off and landing.

I looked at the several Lake AFMs in the collection, but they were for models with 200 hp or 250 hp engines.

The Lycoming IO-360 Operator's Manual has fuel pressure limits for the IO-360-B1A, and they are much lower than for other models. The fuel pressure at the inlet to the Simmonds fuel injection system must be between +2 and -2 psi. Is it possible that your aircraft has an electric pump that is putting out more than 2 psi?

[Mike S]

Jim, welcome aboard the good ship VAF