73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1984 bad boy on August 10, 2009, 12:20:08 am
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hi everybody first off let me introduce myself as i am new. my name is jamie and i own a 1984 k10 scottsdale 4x4 swb(bad) im 24 yrs old but i imagin u guys r more intrested in what goodies the truck has. well i started with a 4 inch suspension lift some american racing wheels n a set of 35/12.50/15. then i added a brand new goodwrench 700r4 and a rebuilt np208. heres the good part a 355 completly rebuilt at the some of 2600.00 performer rpm cam,intake toped with a 750 edelbrock. 10.1 compression and well lets just say its hooked up. the exhaust is edelbrock fullenth headers with 3 inch dual into a h pipe then to some very loud glass pack. and of course rusty rockers l.o.l. but anyway heres my problem i cant get any wheel smokin power off the line. its a stock rear but i dont know what it is thats what id like to know if anyone does theres no numbers that i can find the other thing i was wondering is what you would recomend as far as gear ratios go. keep in mind i need to comfortably run 70 mph down the rd. also i have a set of 4.11 gears from a 2 79 camaros that had the 10.5 10 bolt would they work in the truck. thanks for all your help in advance i really do appreciate it fellas ;D
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the formula for rear ratio is
if your running 50 mph @ 2k w/ 38" then
your ratio would be about 4.53
rpms x tire size / 336 / mph = ratio
2000 x 38 / 336 / 50 = 4.53
or you could use this web site
http://www.idavette.net/tech/ratioc.htm
in mine with 38's and 4.53 i have to push it to get up to 70 and then thats as far as it will go unless going down hill but up hills will drop it back to 60 no problem at all lol
with the 35's and 4.11 you should be around 2762 rpms with a 1:1 trany ratio
with my 38's and 4.53 i run about 2800 so i think you should have about the same problem with a lower rear. i wouldn't change it a bit