have a 351w, alum. heads, comp cam, roller rockers. C6 transmission. 17" wheels right now, but wanna go bigger eventually. PUtting a ford 9" in the rear, but can't figure out what gears i wanna put in. It's my first build. Kinda wanna cruiser/grocery getter. But might go on road trips from time to time. oh, 55 ford f100. Thanks for any advice fellas.
http://vexer.com/automotive-tools/speed-rpm-calculator This is a nice convenient tool. Figure on your engines power band, and what speed you would like to be cruising at.
You have lots of options man. Actually more than just those ratios with a nine inch rear end. You really have to figure out what you are using the car for. You need to really think about this before you just jump it. In my car I am running a 4:44 gear in a ford nine inch with a tremec five speed with 29 inch tires. First, Second, Third, Fourth are a handfull. But slip into that fifth gear .64 overdrive at 68 mph and I get 25 miles to the gallon and the car is tacing at 1900RPM. I love my set-up. I drove this thing all the way to California last summer from Toronto Ontario, Canada. Jay
We'd need to know something about the cam profile in order to know where the optimum RPM of your engine would be.
I'll have to dig up the paperwork on the motor. Bought it from P.O. This truck is gonna be primarily my grocery getter. Although might wanna go on freeways time to time. I know I'll probably be updating the tranny sooner than later. That Overdrive sounds nice... Any opinions on these two? http://phoenix.craigslist.org/nph/pts/3737316950.html http://phoenix.craigslist.org/evl/pts/3686134220.html
More like: 2.50, 2.80, 2.86, 2.91, 2.94, 3.00, 3.07, 3.10, 3.15, 3.25, 3.33, 3.40, 3.45, 3.50, 3.55, 3.60, 3.70, 3.75, 3.82, 3.89, 4.00, 4.11, 4.22, 4.33, 4.44, 4.50, 4.56, 4.63, 4.71, 4.86, 5.00, 5.14, 5.29, 5.43, 5.67, 5.83, 6.00, 6.20, 6.33, 6.50, 6.60, 6.80, 7.00, 7.20, 7.40.
That sounds like a great set up for 3.55's.... I had them behind a 351W and a C4 and was happy with them. Now running a 4.33's behind a T56...
Wheel size wont matter much. In order to determine your final ratio you will need your tire height or overall dimension size. Il also agree with the comment about your cam performance range. You will be served well if you balance your cruising rpm with your final drive ratio. The www.project33.com site has a very effective calculator which should help. I also have a self-created excel spreadsheet which has most transmissions listed and allows you to change your gear ratio to fine tune the outcome. This eliminates the potential to miss the perfect combination. PM me and I will email the spreadsheet to you if you like or send me your specifics and I will return the calculated results. Posted from the TJJ App for iPhone & iPad
I’ll teach you the math and you can easily work it out yourself. The formula for calculating the desired ratio is RPM x Wheel Overall Diameter then divided by MPH , then divided by 336 again [ a mathematical constant ] = overall ratio So if you want to cruise at 2400 RPM with 26 inch tires at 60 mph it would be 2400 x 26 divided by 60 then divided by 336 = 3.09 another example 2700 RPM with 25 inch tires at 70 mph it would be 2700 x 25 divided by 70 then divided by 336 = 2.86
I have a 331 CI SBF in my model A (avatar is the "before" picture) W/ a T-5 (.63 OD) and a 9 inch. I asked the same advice of some clubmates and people "in the know." I didn't ask here, but I wish I would have. On advice from others, I went with a 3.70 gearset, with some protesting it was too low (short, high numerically). Afterwards I figured out that none of the people I asked had selected gears for a vehicle with tires much taller than 24" or with an overdrive. To be fair, it is cammed up, with AFR aluminum heads, RPM Air Gap, and a 13 Lb Aluinum Flywheel (I told everyone I asked the specifics of the engine and trans, AND that I was running 28" tall tires). Point being, 5th gear wasn't useful below 70 and first was pretty rough for the first 20 feet or so. I run a 4.30 now, it's much better suited to my combination. That's why some of the people that have responded are asking for more specific data. They need: Tire size and approximate vehicle weight For the engine they need: Cam specs Compression Actual displacement (351, or has it been bored or stroked?) Head specifics (valve size, port volume, chamber volume, brand wouldn't hurt) Induction (dual or single plane, How many carbs, or is it fuel injected, etc). Exhaust (planning on iron manifolds, zoomies, tri Y, merge collector, lakes or any other form of header). Or a dyno chart (if you have one ). For the trans: What converter do you have for your C6 (intended application, or stated stall speed if after market)? Are there any mods to the vehicle that affect how it drives on the highway (lowered to "road lizzard", nose bleed stance, chop, channel, section, all 3? ). Good luck, sounds like a neat ride when you get it sorted.
Hey guys I'm running a 350 with a slightly over stock cam and a 700R4. The rear is a ford 8" with 3:50-1 posi in it now. The vehicle is a glass 34 tudor. Estimated weight is going to be about 2400 pounds with me in it. The rear tires are 30" tall. I have a chance to change the rear gears for next to nothing (gaskets washers and some lube is all it will cost me). So I'm thinking 3:90 or 4:11. Or should I stay with the current set up? What do you guys think? Sorry I don't know the cam power curve (wish I did).
For that, with 30" tires, 4.11's could work. Since the car is light, the 3.90's would work too. In your case, since the power curve is unknown, finish the car first, and then drive it. The real-world performance will tell the tale on the power curve.
351w, alum. heads, comp cam, roller rockers. C6 transmission. 17" wheels right now, but wanna go bigger eventually. ????
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