Holley 12-804 Chrome Carbureted Fuel Pressure Regulator - Adjustable

In this review the Holley 12-804 Chrome Carbureted Fuel Pressure Regulator is judged on fit, finish and operating control for carbureted engines. It is best for owners running traditional carburetors like Weber 32/36 setups who need a simple, adjustable way to keep pump pressure in check; the single biggest reason to buy is the precise, factory-preset baseline and straightforward adjustment that make dialing in pressure quick. The review looks at build quality, ports and installation to help decide if it suits a restoration or performance street build.

Key Features

• Adjustable pressure range: The regulator adjusts from 1 to 4 psi so users can match fuel pressure to needle and seat assemblies for reliable carburetor operation.
• Factory preset: Pre-set at 2.8 psi at the factory, which gives a sensible starting point and reduces guesswork on first installation.
• High-flow restriction: The 220' (7/32') restriction balances flow and control for typical carbureted applications that require steady fuel delivery.
• Robust plumbing: 3/8' NPT ports with one inlet and two outlets provide straightforward plumbing options and a secure threaded connection to the fuel system.
• Chrome finish and bracket: The chrome finish provides a tidy appearance for show or restored engines, and the included mounting bracket simplifies securing the regulator.

Who It's For

The Holley 12-804 is aimed at classic car and hot rod owners running carburetors who need a simple, adjustable regulator with a clean appearance; it is particularly popular with users of Weber 32/36 carburetors who value ease of adjustment and a solid build. Mechanics and hobbyists who want a regulator that arrives with a sensible factory setting and uses common 3/8' NPT plumbing will find it convenient.

It is less suitable for systems that require pressures outside the 1 to 4 psi window or for installations that need threaded mounting holes without modification. Buyers who must guarantee ultra-precise regulation under all operating conditions should verify compatibility with their specific carburetor and needle/seat combination before purchase.

Pros & Cons

Pros

• Solid build quality and a clean chrome finish that enhances engine-bay appearance.
• Easy to adjust and arrives pre-set at a useful 2.8 psi for quick initial setup.
• 3/8' NPT in/out ports and two outlets offer flexible plumbing for common carbureted systems.
• Includes a mounting bracket for straightforward installation.

Cons

• Some users report mixed results with pressure regulation under certain setups, so verification with the target carburetor is advised.
• The mounting holes are not threaded, which can require additional hardware or modification to secure cleanly.

Specifications

Brand	Holley
Model	12-804
Pressure range	Adjustable 1 to 4 psi
Factory preset	2.8 psi
Restriction size	220' (7/32')
Ports	3/8' NPT (1 inlet, 2 outlets)
Finish	Chrome; mounting bracket included

Our Verdict

The Holley 12-804 is a practical, well-built regulator for carbureted engines that need a modest, adjustable pressure window and a tidy chrome appearance. It represents good value for restorations and street builds where ease of adjustment and common 3/8' NPT plumbing matter, though installers should be aware of reported variability in regulation for some setups and the unthreaded mounting holes.

Frequently Asked Questions

Is the regulator ready to use out of the box?
Yes, it is pre-set at 2.8 psi from the factory so it can be installed and fine-tuned immediately.

What fittings are required?
The unit uses 3/8' NPT ports; one inlet and two outlets accept standard 3/8' NPT fittings or adapters for common fuel lines.

Will it work with Weber 32/36 carburetors?
Many users report good results with Weber 32/36 carburetors, but some have seen mixed regulation performance, so confirm compatibility with your needle and seat and test under real operating conditions.