How to Identify a Holley 4 Barrel

Holley performance carburetors come in two distinct styles, the two barrel and the four barrel. Both configurations can be naturally aspirated or fuel injected and share similar design features pertaining to tuning cams, metering block features, jet positions, fuel float adjustment, accelerator pump assembly and fuel delivery nozzles. Despite their similarities, the four barrel design and model can be quickly identified visually without the need for dismantling the carburetor.

Instructions

1

Unscrew the wing nut on the top of the air filter canister with a pair of pliers and pull off the top of the air filter canister. Slide the air filter and filter base off vertically to expose the carburetor choke tower, where the barrels are housed.

2

Look for the tell-tale double or quad barrel. If you see four round holes in the top of the Holley, it's a four barrel carburetor.

3

Examine the upper right-hand corner of the choke tower to locate the list number. This identifies the model of the four barrel. If the carburetor does not have a choke tower, a design feature indicative of the 4150 HP models, look behind the throttle body linkage on the driver's side of the carburetor to locate the list number.