Youtube user Thunderhead289 does a great job covering the basics of tuning a Holley carb along with providing advanced tips for the more experienced gear heads. These first two videos will help you set your base idle settings, and differentiate between your ported and manifold vacuum. The last video covers the Holley accelerator pump set-up and tuning.
Whether you are a carb veteran or newbie, these videos will give you a better sense of how to truly tune that Holley of yours.
Check out Part III of this video series here.
Idle Setting & Initial Ignition Timing (Part 1)
1. Start by turning idle mix screws all the evenly in small increments.
2. Once they are seated you are looking for about an 800 rpm idle to set.
3. Make sure engine is warmed up before moving distributor
4. Stick a vacuum gauge on carb and make sure you are at full manifold vacuum.
Ported vs Manifold Vacuum Advance (Part 1.5)
Insights into running manifold vs ported vacuum
Holley Car Accelerator Pump Set-Up & Tune (Part 2)
1. Be sure to make sure pump cam is at proper position to start
2. To adjust accelerator pump use feeler gauge to make sure there isn’t much play.
3. Whenever you make an adjustment to your throttle shaft position you will have to re-adjust accelerator pump lever since the geometry will ultimately change.
4. Larger cams, more cam duration, low idle vacuum = larger squirt nozzle.
Smaller Cams (more streetable), smaller CFM carb, 14+ in Hg Vacuum = stock (31) size squirt nozzle