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Don't be "That Guy"
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7,400 Posts
from most of the reading here everone likes 456 rear gear. Im new to fuel injection hot rodding but on carbed motors a low gear makes up for weak motor, just wondering what everones thoughts is on this?:huh:

even in carb'd hot rods, low gear does not "make up" for "weak motor" your parts have to match each other. high rpm HP race type cam? it's not going to have any "off idle grunt" so you need a loose torque converter and high numerical gears to make it all work...but that's ok, because you'll be turning your motor to 7,000 rpm anyway.

vs a torque cam that has lots of off idle torque and grunt, but is all used up by 5,000 rpm. in such case, you want a tighter torque converter and lower numerical gears.

it's not a matter of "weak engine vs strong engine"

and the 4.7s are rev happy motors. the factory shift point is 5500 rpm at WOT. the older 5.2s and 5.9s were around 4800 with the rev limiter at 5200rpm.

anyway, the reason so many guys like the 4.56 is because of tall truck tires and the OD gear in the automatic trans. most of these trucks came with factory 29-31" tall tires. a 3.55 in these trucks is like a 3.21 in a car, because the car will have at most, a 26" tire (typically)

throw in body/suspension lifts, tires taller than 31s, and suddenly that 4.56 behaves like a 3.70 gear in a car...or 3.55 once OD kicks in.
 
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