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HOLLEY 2 & 4 PORT BILLET FUEL PRESSURE REGULATORS
P/N 12-883, 12-884, & 12-885
Installation Instructions 199R11173
WARNING! These instructions must be read and fully understood before beginning the installation. Failure to follow these
instructions may result in poor performance, vehicle damage, personal injury, or death. If these instructions are
not fully understood, installation should not be attempted.
APPLICATIONS:
2 Port Regulator, Double Adjustable, Return Style
2 Port Regulator, Double Adjustable, Return Style
4 Port Regulator, Double Adjustable, Return Style
INTRODUCTION:
Congratulations on your purchase of the Holley 2 or 4 Port Regulator! Holley Performance Products cannot and will not be responsible
for any alleged or actual engine or other damage, or other conditions resulting from misapplication of the parts described herein.
However, it is our intent to provide the best possible products for our customer; products that perform properly and satisfy your
expectations. Should you have any questions, please call Tech Support at 1-866-464-6553, M-F, 8-6 CST & Sat. 9-3 CST. Please
have the part number on hand of the product when you call.
NOTE: Alcohol engines typically require 3-5 psi at idle and 9-11 at WOT.
Figure 1
INSTALLATION:
1. The double adjustable regulators are designed to work with belt or cable driven fuel pumps where the at-idle pressure and full
throttle fuel pressures require separate settings. In these instructions, we have provided two fuel system diagrams for your
reference. However, we recommend that you follow your fuel pump manufacturers recommendations went plumbing your fuel
system.
2. Connect the outlets of the regulator to the carburetor (if the regulator is installed before the carburetor per Figure 2a). If the
regulator is installed after the carburetor (Figure 2b) the outlet needs to be plugged.
NOTE: The regulator is equipped with the vacuum/boost reference port connection on the cap. This can be connected to full
manifold vacuum to slightly decrease fuel pressure at idle and cruise. This is a requirement on forced induction engines,
so that the differential fuel pressure stays constant under boost.
