Ok... the Currie 9" shows up tomarrow and my local guy is setting up a third member. I now need to make a choice on what rear gear to run.
It comes down to 3.50/3.55/3.70/3.73. The car will be driven on the steet alot but see some strip time as well. My goal for the car is to be able to 60 foot in the mid 1.6's and run high 11's. My dad seems to think the 3.50's and I am thinking 3.70's. The tires are 275/50/15 BFG dr's.

ummmm if i was in ur shoes i would go wit 355s but thats just my opion and i know its gonna be hard for me to go that fast threw a 1/4 so..... the 3.55s are a great set but those gears are not going to help u that much itll just make u hook thats it...... if u went with the 373s your going to be running about a tenth or so faster at most than with 355s peeps have went from 273s to 411s sure they were gettimg up and going faster but still they were running basicly the same et. i would go wit the 355s but its ur car.....

maybe someone else will chime in and correct me if im wrong.......

Well, how much of your street time versus strip time is it percentage-wise? If you're going to the track two or three times a year, then go with the 3.50s. If you're going to the track three times a month, then maybe the 3.70s are what you want.

Is the rest of your combo optimized for the gear choice? There's not a ton of difference between the two, but if you do a lot of highway driving with the car you might be more comfortable with the 3.50s long term.

High 11s as your goal...what's the rest of the combo? Small or big block? If you don't have more cubes helping you out, then you may have to rev it more for the necessary power = deeper rear gears.

I'm no expert, just tossing out some thoughts.

Here is the combo:

408 sbc
AFR 195's
xs274s solid cam
1.52 rollers
Holley 750 DP
9.6 to 1's
TH400 with BTE 3500 converter
26" tires
1 3/4" headers
3" x pipe...3" flows

Car will see a bunch of street time and some stip time. But....the car needs to run 11's!!

im thinking u have a pretty good setup but im not totally seeing 11s for u maybe in the future but not as is..... motor marty and his camaro runs 11s but he has a radical bad@ss setup but with some tuneing and $hit i think u could get mid 12s...... what type intake do u have????

I had a best 60' time of 1.69 with 3.70's and a 28" tire. In my Elcamino.

I run 3.73's with a 408 big block, T400 and same tire size. 496 motor in the near future - gears will stay at 3.73. Cruise in the right lane at 2800 RPM, get there when I get there. 3.73's are not really that steep.

how hard are you turning the engine? if you already have the motor together and have the feel of it.......it would be best to pick the rear gear at this time to maximize the full rpm range in which your car runs........

what good is the 3.50 gear if your crossing the finish line at 5000 rpms when the motor pulls hard and likes 6800 rpm shifts. where ever the best peak rpm is pick the gear that would get you closer to that......but be sure to leave some rpm on the table.....you dont want to run into problems with running out of rpm's to finish the 1/4 mile.......

3.73 with the tire you have would be just right. The engine doesn't care how many rpms it turns on the highway as long as the cooling system keeps it around 210. Small blocks like some gear. As far as fuel economy goes, who cares? Besides, under gear it with the cam you have and it'll be a turkey around town.

If it were me I'd put a 4.11 in it and let it eat.

Gary

I've got 4.11s in my '71 Velle, 388ci and a Th350 with a B&M Holeshot 2000 converter. I love it!!! My daily driver, drive roughly 20 miles to work on the freeway and another 20 miles (more if I take the streets) back home. It does kinda get boring driving at between 3200-3500rpms @65mph, but once I'm on the street, that's where I'm really loving it ;) :D


My opinion, go with your gut! If your looking at 3.70s or even 3.73s for that "slight" umph, then go for it!!! Good luck! graemlins/thumbsup.gif

Go with the 3:73 gears, if you have the traction problems I expect, you'll go to a taller tire.

i would go with at least 3.73's if you are wanting high 11's. i second the 4.10/4.11 suggestion too. i don't see it being to incredibly hard to get into the 11's as long as your car is around 3400lbs or less. my best friend is running 11.80's with a 383, with a 3.73 gear, at 3500lbs+, and it has a flat tappet hydraulic cam in it. if my 406 doesn't push my 71 chevelle to high 11's i'm going to be crushed, even at 3700lbs. so i don't think it's going to take rocket science to get a 69 camaro into the 11's with a similar engine/drivetrain set up.

Originally posted by N2097ss:
Go with the 3:73 gears, if you have the traction problems I expect, you'll go to a taller tire. bigger meats are cooler anyway! graemlins/thumbsup.gif

Do like I'm doing for my Son's car, set up two centersections with different gears. 9" parts are cheap, 3.50's for the street and 4.10's for the track. The centersections only take about 30 minutes to swap when you know which tools to grab out of the box.

And make sure a drainplug is installed on the housing bottom before your shop builds the rearend. Makes changing centersections a whole lot cleaner.

Thanks guys, I ended up going with the 3.55's. I think this will be a good compromise for it. Desktop dyno shows the motor peaking at 5400rpm. I figured I would trap around 115 and that puts it at like 5100 rpm with factoring in converter slip. I am hoping to cross the strip at about 5300 to 5500 rpm. Oh yeah..the intake is an Air gap rpm.

Good luck with everything! Good thing its easy to swap gears in those, if you need more to hit your 11 goal ( which you likely will), it'd be a snap to swap.

Originally posted by 6D9:
Thanks guys, I ended up going with the 3.55's. I think this will be a good compromise for it. Desktop dyno shows the motor peaking at 5400rpm. I figured I would trap around 115 and that puts it at like 5100 rpm with factoring in converter slip. I am hoping to cross the strip at about 5300 to 5500 rpm. Oh yeah..the intake is an Air gap rpm. i kind of think the motor will want more rpms than DTD has told you. i bet it'll want shifted at around 6000-6200rpms. i might be wrong, but with that cam, headers, and 3" exhaust, it'll rev, i'm sure of it. ;)