Author Topic: Gear choice for 1/4 mile  (Read 3273 times)

0 Members and 1 Guest are viewing this topic.

fallguy72

  • Jr. Member
  • **
  • Posts: 36
    • View Profile
Gear choice for 1/4 mile
« on: May 01, 2015, 07:20:20 AM »
Looking for advice on gear choice for 1/4 mile. I will be running my 66 Fairlane GTA: 445 ci, 10.2 pistions, 280h comp cam with recommended springs, bone stock heads c6ae u, performer rpm intake, holley 750 dp, fpa headers, 255/60/15 M/T slicks, 2200-2400 stall. I ran 4.11 last year and limited out at 5800 rpm 100mph (my choice) with the old 390. Should i turn up my rev limiter, step up my gears or a combination of both? Would 3.70 be to high?
I ran 13.20 @ 100 with some nitrous last year but don't really want to put it on the new motor.


machoneman

  • Hero Member
  • *****
  • Posts: 3855
    • View Profile
Re: Gear choice for 1/4 mile
« Reply #1 on: May 01, 2015, 08:40:49 AM »
I'd run it a few times the way it is. Then, if you end up bumping the rev limiter before the stripe, raise the tach's rpm limiter point until a.) you either hit the stripe or b.) it tops out before it does. If you still end up topping out before the finish line, either re-gear or try a taller rollout tire....assuming you can fit them. 

Those 9" gears and the setup aren't exactly cheap are they?  ;)
Bob Maag

fallguy72

  • Jr. Member
  • **
  • Posts: 36
    • View Profile
Re: Gear choice for 1/4 mile
« Reply #2 on: May 01, 2015, 08:54:22 AM »
i have 3 complete rears 4.11 spool, 3.70 spool and a 3.25 open for highway. a set of 3.89 is about 200$ maybe i will get them and try both. I don't have much experience at the track (5 runs). looking for someone with a similar combo that can give me an idea of what to expect in the way of ET, mph and gear.
 

Joe-JDC

  • Hero Member
  • *****
  • Posts: 1501
  • Truth stands on its own merit.
    • View Profile
Re: Gear choice for 1/4 mile
« Reply #3 on: May 01, 2015, 09:23:19 AM »
What is your goal?  Do you want to go quicker?  If so, you need more gear, and increase the rpm limit to whatever the valvetrain is capable of.  If the engine will turn 6600, and you are going through the lights at 5800, it needs a deeper gear like 4.30/4.44/4.56 etc.  You can figure that out with algebra, or trial and error.  I ran 4.56 in my Mach I.   Joe-JDC
Joe-JDC '70GT-500

fastback 427

  • Sr. Member
  • ****
  • Posts: 442
    • View Profile
Re: Gear choice for 1/4 mile
« Reply #4 on: May 01, 2015, 09:32:28 AM »
What's your tire height?  I've got 3.89's with 29" tire on my fairlane and it leaves like a pooch, 1.76 60 ft.  I was going to go to 4.30 or 4.56. I would leave your 4.11 and bump your rev limit up,  like was mentioned.
Jaime
67 fastback 427 center oiler 428 crank Dove aluminum
top end toploader
67 fairlane gta cross bolted 12:1 390 Dove aluminum top end c6 3600 stall
65 falcon straight axle project
67 mustang coupe project
76 f350 dually 390 mirror 105 4bbl 4spd
74 f100 xlt 390 c6 factory ac

fallguy72

  • Jr. Member
  • **
  • Posts: 36
    • View Profile
Re: Gear choice for 1/4 mile
« Reply #5 on: May 01, 2015, 09:54:49 AM »
the tires i have ordered say 27" tall. valve train is also my concern . what rpm is max safe before pushrods start bending? I guess 4.11 is the way i will go. Really want a 12.99 ET all motor, is this possible with my old car?