Fuel Distribution Blocks & Components

What Does a Fuel Distribution Block Do in Your Fuel System?

A fuel distribution block takes fuel from one supply line and divides it between two or more outlets. It sits between your pump or regulator and the parts it feeds. You run one main line from the tank instead of a separate line to every bowl, carb or rail.

On a dual-feed carburetor, the block supplies the primary and secondary bowls from the same source. On a dual-carb intake, it splits flow between both carburetors. A spare port can also feed a pressure gauge, so you can check pressure at the point of delivery.

Size the inlet so it can flow at least as much fuel as the outlets combined. A small inlet feeding two large outlets limits flow at high rpm.

The block is one piece of the system, so plan the hose, hose ends and adapters with it. Browse the full range of fuel fittings, lines & hose to match every connection. For oil, coolant and brake plumbing, you'll find more in fittings & hose.

Y-Blocks, Dual-Outlet and Triple-Outlet Fuel Blocks

The right configuration depends on how many components you need to feed. A Y-block or dual-outlet block covers most dual-feed carburetor setups. A triple-outlet block adds a third port for another carb, a gauge or a regulator.

Here's how the main options in this category compare:

• Earl's inline distribution Y-blocks come with 3/8-inch NPT, 1/2-inch NPT or -10 AN inlets.
• Mallory offers an aluminum Y-block with 3/8-inch NPT threads.
• MagnaFuel Y-blocks come in a black finish.
• Clear-finish Y-block fittings use -10 AN ports for large-diameter feed lines.
• The Mr. Gasket triple-outlet fuel block feeds three components from one inlet.
• Complete fuel block kits bundle the block with hose and fittings in one order.

Count your outlets first, then use the Outlet Size and Inlet Size filters to match your lines. If you plan to add a gauge later, a block with an extra port saves you from re-plumbing.

How Do You Match Inlet and Outlet Port Sizes?

Match the block's ports to the hose and fittings you already run, or plan an adapter for every connection. Most fuel blocks use one of four connection types.

NPT ports use tapered pipe threads and need a thread sealant rated for fuel. Inlets in this category include 3/8-inch and 1/2-inch NPT. AN ports use a 37-degree flare, and our guide to AN fittings and hose sizes explains what -6, -8 and -10 mean.

Hose barb inlets accept rubber fuel hose secured with clamps, such as 3/8-inch or 1/2-inch hose. Quick-connect ports suit EFI hard lines. The Russell SAE quick-connect EFI adapter Y-fitting fits 3/8-inch hard tube.

If your block and lines don't share a thread type, shop fuel line fittings & adapters to bridge the gap. Building braided lines yourself? Follow our steps on how to assemble AN fittings and hose assemblies for leak-free connections.

Carbureted vs. EFI Fuel Block Applications

Fuel blocks serve carbureted, EFI and diesel builds, and your application sets the port style. On a dual-feed carburetor, a Y-block feeds both bowls from one regulated line. Dual-carb setups use the same approach to split flow between two carburetors on one intake.

Moroso Y fuel block kits and fuel block kits both use a 1/2-inch hose inlet. The JEGS Fuel Line Kit 6AN includes a billet-aluminum Y-block, braided hose and hose ends. It connects dual-feed carburetors to 2-port regulators with 3/8-inch NPT ports.

On EFI engines, a quick-connect Y-fitting can split one supply line between two fuel rails. Diesel owners will also find a solid fuel block for Duramax LBZ and LMM engines.

Whatever you run, the block only works as well as the lines feeding it. Shop fuel lines & line kits to complete the run from tank to block.

Materials, Finishes and Mounting Options

Aluminum is the common material in this category, and finish and mounting style set most blocks apart. You'll find billet-aluminum blocks, aluminum Y-blocks and fittings with polished, black or clear finishes.

Polished blocks suit engine bays where the plumbing stays on display. Black and clear finishes give the plumbing a lower-key look. Use the Finish filter to match the hardware you already run.

Mounting comes in two main styles. Inline blocks and Y-fittings hang in the fuel line and rely on the hose for support, so secure the lines nearby. Firewall-mounted blocks bolt in place, like the polished Edelbrock dual-outlet fuel block.

Edelbrock also offers a Mini Fuel Distribution Block Kit for 3/8-inch hose. If you're relocating the tank or adding a fuel cell, follow our fuel cell installation guide to plan the full run. Then pick your fuel distribution block by port size, outlet count and finish.