• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Best way to get a better holeshot????
#1
HEY HOTRODDERS!

Ive got a 72 fastback with some modest engine mods:
Mild comp cam
Comp roller rockers
Singleplane holley street dominator intake
edelbrock 4 bbl carb
Headers and magnaflow exhaust
(Not sure how much hp it makes. My dad says maybe around 300)

It runs a stock FMX and has 2:75:1 gears in the back.
Im trying to get it off the line faster!

ANY SUGGESTIONS?? (im only 16 and im paying for this whole car myself so money matters)
thanks!!
  Reply
#2
Rear end gears, a 3.50 or so will allow the car to accelerate better. Pay attention in math class and learn about mechanical advantage. Making a car go fast is simple physics and math.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
  Reply
#3
Gears forsure. i went from a 2.75 to a 3.89 and it was a world of difference! a little stall converter would help as well.

THE HOOFBEAT IS LOUDER THAN THE HEARTBEAT!!!!!
SINCE 1964


  Reply
#4
droptop73;162055 Wrote:Rear end gears, a 3.50 or so will allow the car to accelerate better. Pay attention in math class and learn about mechanical advantage. Making a car go fast is simple physics and math.

I agree 100% - swapping gears will probably get you the result you want easier than any other. Replacing my 2.75 gears for 3.50 with TrakLock turned the 'vert into a different car off the line. And I did it without having to refer to my Math/Science teaching background. Tongue And droptop73 is absolutely right about paying attention in those classes if you want to know the reason why the change in rear end resulted in better hole shot performance. Cool

Have fun and stay in school!

Doc

[Image: 6y14ea.jpg]

Project started 8-7-10
Completed: All new suspension, rebuilt 351C H Code bored .030 over with mild cam and intake, new 3.50 TracLok, custom exhaust system
Current "mini-project": interior upgrade Undecided
  Reply
#5
Sounds like you want a better 60 ft. Gears will help that. A hole shot is really about reaction time. Nothing will help that other than practice. Tree 'em.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
  Reply
#6
if it is an 8 inch rear end a 3.40 gear is available . I ran in a similarly equipped coupe back in the late 80's and it was still able to take the interstate for long trips without getting bad mileage, 16-17 all day long. Very snappy, but doesn't overload your tires traction too much either.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#7
Thanks guys! Will freeway driving be possible without running over 3000 rpm? (sayy with 3.40s or something)
Also, any pointers on how to get into the pumpkin? in or out of car? Procedure? I havent messed around with any of that yet.

Thanks for the help!!
  Reply
#8
There are tons of online calculators about finding gear ratios an rpms. I like to use the summit version http://www.summitracing.com/expertadvice...calculator
Just plug in tire size an desired gear ratio and you can find what rpms you'll most likely be at.

To pull out a pumpkin you have to
Jack car up
Pull tires off
Pull axles out
Disconnect drive shaft from the pumpkin
Unbolt the pumpkin and make sure you have a drain pan nearby

THE HOOFBEAT IS LOUDER THAN THE HEARTBEAT!!!!!
SINCE 1964


  Reply
#9
Becareful. The pumpkins are heavy.

If you get up to 3.5 ratio you will lose that fun passing gear you have now.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
  Reply
#10
Higher gears is the simplest way to get off the line quicker, but without an overdrive, your RPMs at highway speed will go up. What is your RPM at 70MPH now? Probably in the high 2,000s?
  Reply
Share Thread:  




Users browsing this thread: 1 Guest(s)