[Tom Vaught]

I am going to try to list a number of solutions to try when working on a Holley Carb.

I will start with the initial engine start or lack of engine start with the carb installed on the engine.

1) Engine will not start:

a) Prime the Carb with fuel
(easiest way to do this is (with a squirt bottle of fuel) by squirting fuel down the vert tubes on the front and rear bowls).

b) Check the Float Level. Using a normal Holley fuel bowl, the fuel should just be BELOW the Hole threads on the fuel bowl with the plug removed.

c) Check the ignition system for spark to the plugs.

2) Backfires thru the Carb

a) Check the Ignition Timing

b) Turn OUT the Mixture Screws

c) RAISE the fuel Level in the Bowls

d) Adjust the Throttle Plates for a "square opening below the throttle blades". Readjust as required.

e) When all else fails, go up two jet sizes on the Primary Main Jets.

3) If the engine has "backfires" thru the Exhaust System

a) Check for Proper Ignition Timing

b) Turn in the Mixture Screws 1/4th of a turn and see if backfires go away.

c) Lower the Float Levels in the Fuel Bowls

d) Adjust the Throttle Plates for a "square opening below the throttle blades". Readjust as required.

e) Lower the size of the Main jets on the Primary side of the carb.

4) If the Fuel Level in the Bowls cannot be set properly.

a) REDUCE the Fuel Pressure to the Carb

b) Remove the Needle & Seat Assemblies and check for grit/foreign material stuck on the needle or seat.

c) Move the Floats thru full travel and check for binding or the Umbrella seal for the Accelerator Pump has not been trimmed to shortest height
(Allows fuel travel of the float).

5) Fuel Shoots out of the Vent Tube on the front or rear bowl.

a) Lower the fuel level in the Fuel Bowl.

b) Remove the Needle & Seat Assemblies and check for grit/foreign material stuck on the needle or seat.

c) Lower the fuel pressure to the carb

d) Move the Floats thru full travel and check for binding or the Umbrella seal for the Accelerator Pump has not been trimmed to shortest height
(Allows fuel travel of the float).

That concludes the initial fire-up checks on the carb. More on the next steps (Engine actually starts and runs) on another post.

Tom V.