Technical Support - Electronic - Fuel Injector Manifolds
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Manifold Installation

The information below is provided to help in the installation of your injector. If you have any questions or problems during your installation, please call the EFI tech line.

Braided lines
All braided lines need to be thoroughly flushed after assembly. The use of a hacksaw, cutoff wheel, etc. creates a tremendous amount of debris, therefore the use of a braided steel hose cutter is recommended.

Injector installation (3-piece models)
Trial fitting your injector is recommended before final installation. Use silicone for the end rail gaskets

3-piece injector installation:
1. Trial fit injector and plate assembly
2. Glue intake gaskets to head and trim gasket if required
3. Install one half of the injector and torque to spec
4. Lay a large bead of silicone on all 4 edges of the lifter valley plate
5. With a helper, hold the lifter valley plate in place without touching the previously installed injector half and the engine. Slightly tilt up the plate to allow room for the other injector half to slide down onto the head
6. Together, slide the injector half and the plate down to their final resting place
7. Torque injector to spec and tighten lifter valley plate screws

BBC additional instructions
BBC applications require the lifter rails to be drilled and tapped to accept (2) 1/4-20 screws to mount center plate. All BBC applications should use a 1275 FelPro gasket or equivalent.

351W additional instructions
Engines with the three piece 351 injector require the lifter rails to be drilled and tapped to accept (4) 10-24X3/4 screws to mount center plate

348/409 additional instructions
348/409 Distributor Installed Height: Oil pump tang engagement and distributor gear engagement must be verified using the supplied distributor adapter. If required, this adapter can be machined to set distributor height and is o-ringed for a leak free seal.

348/409 Valley Plate Installation: Due to the unique design of the lifter valley rail, additional sealant will be required on the left rear corner of the valley plate to ensure a leak free installation. 348/409 applications will also require the lifter rails to be drilled and tapped to accept (2) 1/4-20 screws to mount center plate.

Throttle Return Springs
Due to the possibility of twisting the butterfly shafts and/or causing drivability concerns, it is recommended that throttle return springs be attached to the throttle arm or a secondary throttle arm that is mounted next to the throttle arm. A throttle stop should be positioned next to the throttle arm to reduce shaft twist from the return springs. Return springs are not supplied by Hilborn.

Idle Speed
Idle speed is adjusted using the idle stop screws on either side of the injector. Which screw to use to set the adjustment depends on where the return spring is located. It is recommended that the idle screw positioned next to the return spring be used as the main idle adjustment. The secondary stop is correctly adjusted when light return pressure is applied by hand to the throttle stop and the throttle blades do not move.

Linkage
Throttle arms are provided as a means to attach your vehicles linkage or cable to the injector. Brackets may need to be constructed. When constructing your linkage please remember:

•  There should not be any bind in your linkage system
•  A mechanical throttle stop should be used. Do not use the injector as the stop or damage to the shafts and couplers could result
•  If a throttle arm is moved verify that it is next to an injector throttle stop    
•  It is recommended that the throttle return spring be attached to the same point on the injector as the throttle linkage.
•  Avoid using the hex link as it is needed for adjustment
•  Throttle shafts and couplers can be easily bent and care should be taken not to introduce twist into these assemblies. Design your linkage placement and return spring arrangements accordingly

Vacuum Kit
On naturally aspirated applications the vacuum kit is comprised of the rubber lines attached to a block mounted in the center of the fuel injector assembly/manifold. A -6 AN fitting is provided to supply vacuum to those accessories that require it. For blown applications a single -6 fitting is provided.

! Warning:  Do not attach a fuel line to the vacuum nipple.

Coolant
Hilborn Injectors are supplied with (2) -8 nipples for coolant flow out of the engine. These nipples must be positioned at the front of the engine or engine damage may result. If additional coolant flow is required larger nipples may be substituted. Additional nipples may be added to the rear holes of the injector to help cool the rear of the engine.

Magnetos
Magnetos are not compatible with EFI due to electromagnetic interference (EMI). If a magneto is desired consult your magneto manufacturer for electronic conversions.

Alternator
In order to keep the battery in a fully charged state it is recommended that the alternator output wire be attached directly to the battery. This will keep voltage drops to a minimum allowing the full potential of the alternator to be used. A minimum of an 8 gauge wire is recommended. 
! NOTE: One wire alternators produce a large amount of ripple, therefore it is highly recommended that the output be attached directly to the battery to provide adequate buffering of the ripple.

Please contact our EFI Tech Line for assistance with any of these procedures