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3.73 --or--4.56

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Post  johndickjr August 11th 2011, 2:18 pm

i can not decide on if i should use 3.73 or 4.56 gears, motor is a flat top 429..i am using stock car rods ..solid roller cam, 2500-6800 , ported big vale doves and a blue thunder intake, tires on my car are 31-10.5w ,

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Post  Curt August 11th 2011, 2:23 pm

Is this a drag only car?
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Post  johndickjr August 11th 2011, 2:36 pm

Curt wrote:Is this a drag only car?
yes drag only car, we run mostly 1/4 mile and some 1/8 mile races , i dont plan on shifting high rpm, will have to test to see where car like to be shifted at , probably around 5500 range

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Post  Curt August 11th 2011, 2:45 pm

the shift point isn't as much as a target as the finish line rpm. My goal is to shift at 200 rpm over peak HP. But with the factory rods, you should get the highest gear available to cross the finish line at the desired RPM.



But for sure if you have the two gears mentioned, the 4:56 will be your best choice.
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Post  lghting94 August 11th 2011, 3:08 pm

What transmission?
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Post  johndickjr August 11th 2011, 6:50 pm

lghting94 wrote:What transmission?
c6

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Post  johndickjr August 11th 2011, 6:51 pm

leaning toward 4.56, which is a tad high , but im thinking it will be ok, since i have 31 inch tall tires

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Post  Curt August 11th 2011, 6:55 pm

Actually it wont be. You will be very close to 5500 at the stripe unless you're making a ton of HP on that almost stock motor. Transmission won't make any difference except on the line, you'll be at 1 to 1 at the big end.
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Post  richter69 August 11th 2011, 7:23 pm

weight of car and converter?
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Post  johndickjr August 11th 2011, 7:49 pm

Curt wrote:Actually it wont be. You will be very close to 5500 at the stripe unless you're making a ton of HP on that almost stock motor. Transmission won't make any difference except on the line, you'll be at 1 to 1 at the big end.
5500 with what gear? wallace rpm calultor says with a
4.56 gear
6500 RPM 131.46 MPH
6000 RPM 121.35 MPH
5500 RPM 111.24 MPH

3.73 gear
5500 RPM 135.99 MPH
5000 RPM 123.63 MPH
4500 RPM 111.26 MPH

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Post  johndickjr August 11th 2011, 7:50 pm

richter69 wrote:weight of car and converter?
converter is a b-m 2500---unsure of car weight...with a bbc and a glide it was 2790

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Post  richter69 August 11th 2011, 8:18 pm

tight converter I'd go with the 4.57.
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Post  johndickjr August 11th 2011, 8:33 pm

richter69 wrote:tight converter I'd go with the 4.57.
ok..will do

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Post  richter69 August 11th 2011, 8:43 pm

good choice, with the tight converter and short stroke, tall tire...........it would be a serious turd in the 60' dept with the 3.73.
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Post  johndickjr August 11th 2011, 8:50 pm

richter69 wrote:good choice, with the tight converter and short stroke, tall tire...........it would be a serious turd in the 60' dept with the 3.73.
going to run this motor and build a bigger motor over the next year... r u coming up to the labor day race in Tulsa...

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Post  richter69 August 11th 2011, 9:24 pm

what race?
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Post  johndickjr August 11th 2011, 10:25 pm

richter69 wrote:what race?

3.73 --or--4.56 LaborDay_2011

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Post  crittersf1 August 12th 2011, 8:13 pm

4.56 is the better choice of the two
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Post  whitefield August 13th 2011, 12:35 pm

In my opinion I would not use the stall it is to tight .We did a similar build about 12 years ago for a friend of mine with a 3000 stall and to much gear and it ran low 8s and high 7s. with a c-4 trans. changed the gear to 4.11 and a 3800 9.5 and went 7.20s later tuning and cam change it went 6.90 all 1/8th mile car and all motor.

Good luck and in my opinion I would put 4.11 or 4.30 gear with 3500 stall to 4000 stall .
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Post  johndickjr August 13th 2011, 10:53 pm

whitefield wrote:In my opinion I would not use the stall it is to tight .We did a similar build about 12 years ago for a friend of mine with a 3000 stall and to much gear and it ran low 8s and high 7s. with a c-4 trans. changed the gear to 4.11 and a 3800 9.5 and went 7.20s later tuning and cam change it went 6.90 all 1/8th mile car and all motor.

Good luck and in my opinion I would put 4.11 or 4.30 gear with 3500 stall to 4000 stall .
i don't have a 3500-400 converter..and i don't have any other gears...hav to use what i have, poor boys have poor ways

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Post  whitefield August 15th 2011, 9:26 am

I understand ! Cool what rearend do you have a 9in or 8.8?
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Post  johndickjr August 15th 2011, 2:08 pm

whitefield wrote:I understand ! Cool what rearend do you have a 9in or 8.8?
8.8, full spool..35 spline axles...9 inch ends (no clip eliminators)

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Post  dfree383 November 10th 2011, 1:48 am

So sell both sets of gear and get the correct ones...... or swap someone for the right ones?

What about sending the converter back to get it stalled? cheaper than a new one and it get it right?
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Post  IDT-572 November 11th 2011, 6:45 pm

If you don't get the converter to leave at about 200 above torque peak, the gear ain't gonna help a bunch.
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