Holley 3310 - Quick Fuel metering block

[sledger46]

I am running a Holley 3310 Vac secondary carb on a MP M1 dual plane intake and I recently purchased the Quick fuel secondary metering block that uses standard jets as opposed to the stock metering block with fixed jetting. The instructions for the Quick Fuel metering block provides a table to convert the stamped number on the stock metering block to a equivalent jet size.

Here is the question: Knowing it is a 3310 would you

a) Just use the QF recommendation for jets for the secondaries

b) Jet it up 2 numbers

c) Jet in down 2 numbers

 

[Locomotion]

Holley has a secondary metering block for this conversion. Their charts say to use either 75 or 76 jets. Unless there is a difference/imbalance in plug color from front cylinders to rear, I like to keep the OEM balance from primary to secondary jets. In other words, if OEM is 72 primary and 76 secondary, I go up and down equally all around when richening or leaning the carb. i.e.: 73/77, 71/75, 75/79, etc. (It gets a little complicated with a dual plane because of the different levels and crossover ports.) The way I look at it, the engineers had the balance figured out with each respective carb and it should be maintained, unless there is an obvious imbalance for whatever reason.

The Quick Fuel metering block may "act" differently than the Holley, so I would go with their baseline jet recommendation in relationship to the OEM primary size, which I believe is 72.