500hp carb jetting
 

I have twin 500hp factory sealed motors that had prochargers on them. they have been removed. the carbs have been done by nickerson performance. the primary jets are 79 and secondary jets are 99. and a 4.5 power valve. what would be a good jet choice to get them in the ball park?? i was thinking leave the 78 jet in primary and put a 90 jet in the secondary.

Stock HP500 jetting was staggered https://www.offshoreonly.com/forums/...b-jetting.html

thanks . yes i saw that. im not a fan of staggered jetting. that why i was thinking meet in the middle with jetting. wondering what anybody has tried and been successful with?

I ran my 500 hp 454’s with ported dart oval ports the same staggered jetting with great results. Couldn’t have been anymore spot on. I may have been plus or minus on each jet. Nothing wrong with staggered jetting to achieve optimal plug burn.

That’s for factory carbs.
His have been reworked so throw that out the window.

Tru-dat 😎

78/79 in prim be fine and 90’s should be plenty fat but a good starting point and probably end up with 86/87. A quick ph call to Nickerson would be best.

Fwiw, the stagger jetting used on HP 500s was NOT because the factory 850 carb was built with issues, its because that intake is a train wreck and has terrible distribution, Smitty

Combo btwn GM heads and stock dart intake not ideal by any means. Weren’t the carbs 9022 800 Holley’s

Yep. 9022.