Vettrocious

As I've mentioned here before, I'm building a 63 with FAST electronic fuel injection to replace the Rochester unit. Since I've redone the whole engine, (as well as many other things on the car), I'm considering putting on the Rochester unit temporarily during the initial start-up, in order that I don't have to mess with getting the electronic FI running at the same time I'm first starting and breaking in the engine.

This should be no problem, except that I don't know where I should put the regulator to reduce the electric fuel pump pressure to the Rochester unit ( the engine mounted fuel pump is gone). My choices are: 1) put the fuel regulator on the feed line (before the feed to the Rochester fuel bowl) with the return line fed off the bottom of the regulator, or, alternatively, or 2) put a tee at the feed line inlet to the fuel bowl, then just plumb one line back to the regulator that is already on the FAST return line. 3) eliminate the return line for now...

Any help would be great...thanks

MikeM

Don't overthink it.

Set a gas container on the fender and run a siphon hose to the fuel meter.

Unhook the electric pump so you don't burn it up.

Vettrocious

Thanks Mike, that'll work for start up, this winter, so I'll do it that way.

I was "overthinking" in terms of driving the car for a couple of days in the Spring (when its not 17 degrees with 40 mph winds, as it is here today) before I switch to the other plenum and EFI controls.

I know that guys use regulators on carburated engines sometimes, and they put the regulator on the feed line, rather than the return. That'd probably work on a Rochester, 'cause it has its own high-pressure pump.

MikeM

You could always temporarily mount an electric fuel pump by the engine assuming it will pull fuel through a pump mounted in the tank which I assume you have?

There was one guy here a few years ago (lived Smyrna Beach I believe) who adapted a two gallon marine gas tank to run his car. It was placed in the passenger compartment and a hose was run into the engine compartment. Maybe to an electric pump? Matt Gruber was the name. I haven't seen him post here in awhile.

Vettrocious

Yes, the electric fuel pump is now in the tank and it should work fine to get the fuel to the engine. The Rochester unit takes about 7-9 PSI and I can adjust my bypass regulator to regulate to that pressure, rather than the 43 PSI that I'll be using later. Unfortunately my understanding of regulators and is almost nonexistent, though I'm guessing that if mounted either up or down stream from the Rochester's fuel bowl inlet, it will still control the pressure at that inlet.

I need a guy who thoroughly understands bypass regulators to confirm this guess or hopefully tell me where it really should be. It is now mounted as it will be with the electronic injection, downstream, but can be moved fairly easily.

Thanks,

Mike

Avispa

The regulator needs to be mounted upstream of the Rochester fuel bowl inlet. Pressure to the fuel bowl inlet as you noted should be only 7 to 9 PSI. The Rochester FI fuel bowl is the same in principle to a carb fuel bowl; it's just a place to store fuel for delivery to the motor. It's just that for Rochester FI the fuel delivery is done by the high pressure pump driven by the cable to the distributor. Bypass regulators just vent fuel to a return line when the pressure in the pump outlet exceeds the regulator setpoint pressure. Just like the popoff valve on a water heater or water boiler furnace. They're very simple in operation. You do need a fuel return line to the tank to use a bypass regulator (unlike a "deadhead" regulator).

Vettrocious

Thanks very much for the regulator lesson. Both feed and return line are already plumbed from the tank to the EFI injector loop on a modified Rochestier plenum. I just need to remove the return line that already goes from the injector loop to the regulator, substitute the original Rochester plenum, then hook up a line from the regulator to the feed bowl of the normal Rochester. No problem.