[MidnightAuto]

I just rebuilt my top end with kre heads and 60919 cam, on a 461. Mike at Pontiac tripower has been helping me with some bugs that I have mostly sorted out.
As well as recommending My jet set up is as follows, 75-64-75. This is 66 tripower. I am Using an af meter to dial in, plus reading plugs (that were pretty black). So it’s a bit rich. Idle is about sorted now, fluctuates around 12, but light driving had the meter dropping to 10ish. Have not been able to see full wot. Anyway, I am sure I will figure it out, but my question is another topic.

I’ve studied the test omt did with his tripower and it was clear that the key was the center carb. That is where most of the power comes from. In that spirit, I have been hunting for the 1 3/8 Venturi 2 bbl, but they are a bit of a unicorn, never oem on a Pontiac, and infrequently on sbc 400 truck applications. So I gave up and bought this: https://www.summitracing.com/parts/jet-37001#overview, which has the 1 3/8 Venturi plus a couple other tricks to get it to 500 cfm purportedly.

My question is two fold as it relates to jetting. this carb uses Holley jets and came with 74.

(1) why are jets in the center carb always smaller then the end carbs in Pontiac applications?

(2) based on these 74 jets, would you start with those, or get Holley 64’s, similar to what I have now in the carb currently on the motor?

Thoughts welcome. Thanks guys