By FordMuscle staff.
Several months ago we embarked on a very cool project - converting
our Project '67 Mustang from carburetion to fuel injection.
Putting modern electronic engine control under a vintage shell
is on the wish list for many enthusiasts and we were excited
to show you how to do it. In Part
I of DIY EFI we detailed all of the steps involved in
getting the wiring, hardware and fuel system selected and
installed. We used Mass-Flo's Ford EEC-IV based kit which
simplified procuring and installing the various required parts.
The real plus to the Mass-Flo kit is their under-the-air cleaner
mass air meter which maintains a carbureted look. We also
liked the idea of using a modified single-plane carbureted
intake manifold (we used the Edelbrock Victor Jr.) This would
allow the high-rpm capability we desired and make for an interesting
power comparison between carburetion and fuel injection.
The degree of difficulty for converting a carbureted car
to EFI is not terribly high, however there is plenty of time
spent in planning for things like the fuel system and then
properly installing all of the components. This is especially
true if you are planning for significant power upgrades. In
the case of Project '67 the decision to convert to EFI came
after repeated struggles trying to tune the carburetor for
supercharged 331cid engine. We had conceded that we were
likely go broke repeatedly paying for custom carburetor modifications
to provide us with a safe air-fuel ratio for the 8psi of boost
and 10.8:1 compression ratio. We rationalized that the up
front expense for an EFI conversion would pay dividends in
virtually limitless tuneability.
Our EFI conversion kit is by Mass-Flo.
It's based on the Ford EEC-IV system however the throttle
body and mass air meter are purposely designed by Mass-Flo
to fit a carbed single plane manifold (modified for injectors)
and conceal under the air filter housing for a sleeper
The Mass-Flo kit includes a custom EFI wiring harness
in the correct length for your vehicle and stripped of
the various emissions sensors that are not necessary for
engine operation. We mounted the processor and fuse block
under the passenger side dash.
Since we are running 331 cubic inches and a big cam, Mass-Flo
burned a custom tune for our A9L computer. It simply fits
into the service port on the back of the A9L. Mass-Flo
adjusts the parameters for the larger displacement and
30lb/hr fuel injectors and mass air meter.
The fuel system consists of an inline high-pressure EFI
fuel pump to feed the 30lb/hr injectors, a regulator and
return line. With the engine running we adjusted the fuel
pressure to 39psi. It is important to make all fuel pressure
adjustment with the vacuum line to the regulator disconnected.
Pressure will drop corresponding to manifold vacuum once
the line is reconnected.
So the initial plan was to get the engine converted to fuel-injection
and have it running naturally aspirated. Once we got it optimized
and dyno tested to compare against the carbureted setup we're
reinstall the blower and step-up in injector and mass air
size. Since the car would be down during the conversion we
also used the opportunity to install the set of Dart Pro-1
CNC cylinder heads we had featured
some time ago. This would also allow us to drop the compression
ratio one full point and install a set of Cometic multi-layer
steel (MLS) head gaskets to hold in the boost. We concluded
Part I with having all of the hardware, fuel and electrical
work completed. All that was left was to have the exhaust
reconnected and setup for oxygen sensors.
We also installed a set of Dart Pro-1 CNC cylinder heads
while the car was down for the EFI conversion. Take note
of the spark plug angle in relation to header bolt. We'll
comment on this later in the article.
We had our local exhaust shop reconnect the exhaust and
weld in oxygen sensor fittings. We also placed an extra
fitting so we can use our Innovate
LM1 wideband for tuning and monitoring air-fuel ratio.
Not Quite As Seen on TV
Now if this were an episode of Overhaulin' this would be the
point where we'd show you a five second clip of our project
car being fired up, and then we'd all clap and hug each other.
You'd of course be lead to believe we pulled off another major
project without any of the glitches that occur in a real garage.
Well you know by now FM isn't anything like those polished TV
shows. Our projects are like your projects in that they are
rarely completed according to schedule, never on budget, and
certainly not without redoing at least a few critical steps.
Our projects are often filled with real frustrations, and we're
not ashamed to confess to you our shortcomings. But, if you
still want the warm and fuzzy video clip, it's to the right
in the sidebar. We won't complain if you choose to think we
are flawless and infallible. However we presume most of you
won't settle for anything less than some dyno numbers or at
the very least a time slip. We don't have those just yet, but
read on to find out what real problems we've encountered.