Really bad fuel distribution at low throttle opening starving the front four cylinders bad enough to cause detonation
I cut my teeth on a early cast iron in line dual quad intake off of a 1955 Chrysler 300 motor, Mopar, Dodge, Plymouth, DeSoto and Chrysler used that type intake on almost all the OEM dual quad inline intake set ups they sold stock on production cars. They where not real responsive at low speed light throttle driving also
I had a 1957 Chrysler 300C that I took the dual quad set up off and installed a factory single four dual plane intake and a stock WCFB from a 1957 New Yorker motor I had and that big old tank ran and drove a bunch better with the single four set up
that surprised the heck out of me as I had not noticed the 1957 300 being a bunch different driving than the same size 1957 New Yorker we owned and drove before buying the 300. The New Yorker was quicker from a dead stop to around 60 MPH and then the 300 would drive around it and continue to pull away up to 120 MPH or so when both of them big old boats got to uncomfortable on handling to keep my left foot on the floor on the streets back then
Mopar learned it lesson on the 426 Street Hemi intakes, all of them where a dual plane intake with stagger jetting on the carbs to help on the fuel distribution at light part throttle driving and especially at WOT driving, look at the stock jetting on those carbs