Hi. I have a ZZ4 crate 385 fast burn motor in my 90.
When I bought the truck it had a 750 Double Pumper Vacuum Secondaries.
The truck bogs, farts, burps and needs a rebuild.
The 385 fastburn recommends or comes wth a 650 from GM
I have the opportunity to swap my carb I have now for a 600cfm double pumper mechanical secondaries for $120.
Fellow said ill loose maybe a 10th on the 1/4 mile. Which I might run it once a year so timeslips are not that important to me. He says fuel mileage will be better.
What are your thoughts?

 

Take it to someone who can get your 750 running properly. It's either vacuum secondaries or a double pumper, not both.

 

my typo the 750 is vacuum secondaries

 

think im gonna try and find the correct 650 Holley for her