US Jensen owner Bruce
Bridges has undertaken some spectacular projects on his Interceptor 3.
Here is his conversion to a Multipoint 6 Pack E.F.I system.
Here’s the original
set-up on my 1974 Jensen Interceptor III :0.030 over bore10.75:1 JE
lightweight pistons, mild Crane Hydraulic roller retrofit cam,
Edelbrock AL heads, Performer RPM manifold and BG850 carburettor.
The gear set in the diff is 3.54:1. The Interceptors best ¼
mile time was
13.20@107 with a 2.2sec 60ft.
Traction limited, but fun to drive! The other modifications to
the car include a Gear Vendors Overdrive, and TCI 2000rpm stall
converter. Headers are highly modified Delta S&S mid length 1
Digging in (we scheduled
5 days to do the job) We decided to install the fuel system first.
Luckily, The Jensen had ready access to the fuel return/sender via
the trunk. Its just behind that steel panel.
Ryan Vowell came out from
Pearl City HI to guru on the install. Ryan’s company,
Performance Injection, sells the Big Stuff 3 injection system and
Ryan likes to be involved in the installs if possible! He hand
carried the fuel system components on the plane to San Diego!
The huge Essex Fuel pump, filter and Paxton regulator with lots of
-8 AN fittings and line were required to fuel the 440. The huge
sizing of the fuel system will allow future Modifications to the
motor without upgrading the system! We used rubber vibration
isolators to mount the fuel pump remembering what my old Challenger
with its red Holley pump used to sound like. The pump is
very quiet! We are running a return system, so we added a 3/8”
return line into the sender unit and routed new high pressure lines
to the engine compartment. We connected the pump to a 40 amp
solid state relay for computer control. The regulator was
added with an electric pressure gage to keep track of things.
Next step was to install
the manifold. Since it’s a dry manifold the swap is no
problem. We had already port matched the manifold to our new
valley gasket, so we popped it right on. The fuel pressure
regulator and sender for the gauge can be seen mounted to the back
of the rear-most throttle body. We disabled the mechanical
advance with a quick spot weld and cobbled a big hole in the top of
a spare distributor cap to help set up the ignition. Since we
are using an MSD crank trigger and Multispark unit, the distributor
doesn’t do much anymore.
The crank trigger system
was easy to install…provided you’d already figured out what to do
with the extra 3/8” offset on your crank pulley. We actually
thought ahead on this one (thanks Doug!) and made new under-drive
pulleys (and matching water pump pulley) with the offset built in.
Makes all of the original pulleys look kind of beat though.
We’d neglected to really
check out the wiring harness up until now. The Big Stuff 3
harness was complete and nicely loomed. We were able to modify
a few line lengths and move the feed through grommet to make it fit
like a glove in our unique application. Nice Packard/Weatherpack
sealed connectors! The computer is mounted under the glove
compartment shelf. Due to the set-back of the motor, there’s
virtually no room behind the dash. The finish on the computer’s box
matched the back vinyl in the Jensen and is practically invisible.
We added the water
temperature sender to a handy unused radiator tank fitting.
The air temperature sensor went into the back of the manifold where
the vacuum brake line normally goes. We tapped a new fitting
into the manifold for the vacuum lines. The Oxygen sensor was
mounted vertically into a bung welded into the right head pipe. The
manifold pressure sensor (MAP) was attached to the old choke tower
and tubed up to the centre throttle body vacuum port. The
centre TB also gets the throttle position sensor. We mounted
the idle air control motor to the front throttle body.
quite the original look under the hood, more of a road racing look with
the tuneablity and reliability of multi port fuel injection. Now
we can make those long summer drives to the Mopar and Jensen meets like
any modern vehicle… Well not like “any” vehicle…
We started tuning the system with
a non-progressive linkage and a bar actuated (stock) transmission kick
down system. We spent a day or two with that set-up before we
ditched it and set-up an adjustable progressive linkage and a Lokar
cable kick down kit. We fabricated a bottom plate to fit the stock
6-pack air cleaner element and ordered a 6-pack lid. The 6 pack
MPI fits much better under the low hood of the Jensen than the Performer
RPM manifold. We also noticed that the motor was a little quieter, maybe
its because the 6pack manifold sits deeply into the valley pan, reducing
the valve train noise! The initial program the guys at Big
Stuff 3 included in the computer worked to get us started, and once we
got “bugs” worked out of our installation (full throttle travel issues,
IAC motor change from Mopar to GM…) the car is more driveable than with
the carburettor, the eye watering idle is gone, it starts up on the
first turn, and it seems to be getting better gas mileage. The dyno is
the next stop. We also have this system for sale now!
From 900-2300 CFM, Check out
pricing and production release dates!