360 carb jetting help

Most versatile carb Holley ever made for street performance imo. I've probably used close to two dozen on all sized engines before.

Cracked is correct on the #72 primary jet. I'm curious if yours is a 780 or 750? If you could post the list # off the choke horn, it would tell for sure. If it's a 4160 with a secondary plate, it would be a #21 which has a .081 jet orifice.....equivalent to a mid #70's jet. If seen these carbs come with a #25 and #31 accelerator pump nozzle before, and they all came with a plain sec'd spring. It should also have a 6.5" power valve.

Stock jetting is pretty close on moderate small blocks. I have worked with several combo's like yours and found a #28 nozzle was best on a dual plane intake, such as yours, and a #31 worked well on a single plane or dual plane with a spacer. As far as the secondary opening spring, a yellow or short yellow worked best with a 3k converter and a 4.10 gear. The 6.5 power valve should be fine for all but the most radical cams.

Don't forget to get your timing maximized before tweaking the carb, if you choose to do so.