Edelbrock Pro-Flo Multi Point EFI System #3509

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Part I: Opening the Box, Looking it Over

Hmmm...BIG box!

The whole system

Intake manifold assy w/ harness

Intake manifold assy bare

Another view

Progressive throttle

Edelbrock had some help

Weber and Magneti Marelli know a lot about EFI

Mallory billet distributor

Another view

Nuthin' inside!

Oh boy, I've done it now! Except for home computer equipment, I don't think I've ever spent as much money on something that came in a box... Edelbrock had been making their Pro-Flo Multi-Point EFI systems for a few years now, but just recently developed one for the big block Chrysler engines (413/426 Wedge/440).

This will be the third fuel injection system on this bus. The first was a fairly rudimentary 2-bbl Holley ProJection system that was installed by the previous owner. The only sensors that system had were coolant temp (I think), engine speed and throttle position. The next system was an 4-bbl AirSensors system that had coolant temp sensor, engine speed and an air mass sensor (AMS). This resulted in a power improvment over the Holley setup, but still doesn't have any feedback to ensure the proper air/fuel mixture. But the biggest problems are the fact that the system is out of production and the fragile nature of the AMS. Last summer (2003), the AMS hotwire melted while I was passing a car on a rural 2-lane highway - that kind of excitement I don't need ;-)

This Edelbrock Pro-Flo system appears to address all those concerns. It has a more complete set of sensors:

  • throttle position
  • coolant temperature
  • inlet air temperature
  • manifold absolute pressure
  • engine speed
  • exhaust oxygen sensor

Other advantages to this system are the multi point injectors (that squirt the fuel just upstream of the intake valves) and the progressive throttle (only 2 barrels in the throttle body open initially, the other 2 start opening at about 1/2 throttle), neither of which the AirSensors or Holley systems had. With all 4 butterflies opening at once and the injectors mounted high in the throttle body, the AirSensors system had a tendency to "cough" when opening the throttle from idle.

The Edelbrock system is "closed loop" - just like a modern engine. That means the air/fuel mixture is monitored via the exhaust oxygen sensor and continuously adjusted (while cruising) to an optimal mixture - neither wasting fuel nor endangering the engine with a too-lean mixture.

This system also includes an entirely new ignition system - including the distributor. That is a lovely billet machined Mallory piece. It has no vacuum or centrifugal advance mechanisms. It's basically just a crank angle sensor and spark distributor - the electronic control unit (ECU) determines the timing and duration of the spark as well as the fuel delivery.

Finally, the Edelbrock setup includes a calibration module - you don't have to use a laptop computer to adjust the system. The module has a coiled remote cord, so you don't have to have direct access to the ECU, either. No more standing on my head with the flashlight trying to adjust that box!

Please everyone keep your fingers crossed for me that I can get this thing installed and properly calibrated. The first task is to get a new exhaust system made - the current one is in pretty rough shape. I plan to have it made entirely in stainless steel in hope that it might last longer. Then I also have some machining work that needs to be done on some nice new cast aluminum Mopar Performance Parts valve covers... ;-)

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