Reply to "What carbs are you using on your Cleveland motors?"

John,

In 1970 or 1980, if you purchased a list 4779 it had #75 primary jets & #76 secondary jets out of the box. The list 3310, 780 vacuum secondary, had #72 primary jets.

The new carbs are jetted better than they were 20 to 30 years ago. Today the list 4779 carb is equipped with #70 primary jets & #80 secondary jets. Although the older list 3310 was equipped with #72 primary jets, it ran rich. This leads me to believe the fixed jets in the modern carbs are also calibrated leaner.

For comparison, the 770 street avenger (list 80770) has #72 primary jets and #75 secondary jets. The 750 HP carb (list 80528) has #72 primary jets and #84 secondary jets.

If you have any of these modern carbs with #70 or #72 primary jets, I say run it as it came out of the box until you make it to the dyno. If you have an older carb, stuff it with #70 primary jets & #80 secondary jets. While you have that older carb apart, purchase on of those new "re-usable" gasket kits, they are worth their weight in gold.

Set the primary & secondary throttle plates properly (transfer slots exposed below the butterflies at idle), attach the carb to the intake. If you're running a vacuum advance, hook it to "ported" vacuum. Start the motor, set the fuel bowl levels. Adjust the idle jets (for highest rpm / best vacuum). Optimize your static ignition advance setting (highest rpm / best vacuum method). This will get you off & running.

By the way everyone, the jet recommendation is only good for a Holley 750 cfm carb.

Your friend on the DTBB