Rearend gear selection

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Hobbestheman

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I have a 68 Dart with the a 273 engine. The engine has been rebuilt .030 over, Egge pistons, aftermarket rods, cam, performer 4-barrel intake. The original 904 automatic transmission was rebuilt to factory specs. I plan to use 8x18" wheels. The car will be a street/highway/fun. I would appreciate some sound advice on torque converter selection (stock or ?), whether to swap the 7 1/4 rearend for an 8 3/4. I have an A-body 8 3/4 with 742 case. What gear ratio would be appropriate? Open or closed gear? Thanks for your input.
 
Stock 68 a904 v8 convertor stall was@ 1800-1900 rpm depending on rear gears installed in diff. (taller gear 1900, lower gear lower stall 1800)
Lon;
 
Dear Hobbes.
-IMHO,You need to focus. You want "street/highway/fun", with a 273.
-Theres nothing inherently wrong with a 273.Its just that its; well, small.
-To have street fun, will require a different chassis set-up than for highway.
-And then theres the somewhat vague definition of fun. And,street fun, can lead to; accidents, property damage, loss of life or body parts, and/or loss of licence,or liberty, in a hurry.Maybe all in one night.
-Now if you wanted to turn it into a nice boulevard cruiser,well that could be cool.
-So,again, I say focus.
 
I would say 3.55 or EVEN a 3.91. The 273 is a great little engine. It's exactly that. Little. The short stroke and small cube displacement are really fighting against low end torque.

Now if you talk about stepping up to a 360, that's a horse of another color. Because of the additional stroke, the 360's best street gear IMO is a 3.23. It is a fantastic all around gear.

I don't get how anyone can recommend a converter for you. No one can possibly know what cam you have. You've not disclosed that information. Hopefully, the camshaft is a mild one, close to stock. If not, it will really be a dog with a 3.23.....and not much better with a 3.55.
 
Do you know if you have a wide ratio A904 or the standard trans gearing?

......................................1st 2nd 3rd
Standard A904 gearing: 2.45 - 1.45 - 1.00 : 1
Wide ratio A904/998/999: 2.74 - 1.54 - 1.00 : 1
 
jerry6 said:
3:55 or 3:23 make good all around gears . 3000 rpm with 26" tire around 63 mph with 3.55 about 69 mph with 3.23 .http://www.bigblockdart.com/forum/speedtire.php
Click to expand...

A 26" tall tire is about equivalent to a 295/50-15. So that means yesterday. Perhaps the email address was put in wrong? I ran 3.91's with 295's and it was liveable at 60-65mph, and fun "light-to-light". 3.73's might be nice too.

As for convertor, there are too many factors at play for that recommendation, and a good convertor manufacturer is gonna ask a lot more questions than what you've disclosed.
 
wow i dont think you will find a 295 width tyre will fit under a darts arches without leaf relocation and mini tubbing. 245 at best

personally, i would re think what you want from your car, as everyone says, your a little short on cubes, so i would be looking at a cruiser rather than racer, but who am i to say whats best for you.
yes a looser converter will help, but without knowing weight of car, cam and carb sizes, head work, and intake, its best to suggest you talk with a converter company
do some chassis work like tie in the frame, and possibly look at ss springs out the back
a nice free flowing exhaust system will help, alot.
and a nice dual plane manifold and matched 4 barrel too.
 
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