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Dec 20, 2003 | 07:48 PM

92 305 BIRD

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Joined: May 2003

Posts: 186

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From: BAKERSFIELD

Car: 1992 Firebird

Engine: 305 TBI (LO3)

Transmission: TH-700R4 w/Shift kit

gear questions

ok im getting 3.42's put in and my posi is on its way. how much should my et drop just an estimite i have 2.73's right now.

Dec 21, 2003 | 04:06 AM

D Stroy H8

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Joined: Jan 2002

Posts: 1,370

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From: Las Vegas, NV

Car: 1990 Iroc-Z

Engine: L98

Transmission: 700R4

Maybe 2 tenths.
Maybe 3 tenths.

I wouldn't hope for 3. Hope for 2.

Dec 23, 2003 | 08:11 PM

Zepher

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Joined: Feb 2000

Posts: 7,964

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From: Norfolk, VA. USA

Car: 86 Trans Am, 88 Formula

Engine: 95LT4, 305TPI

Transmission: T56, T5

My friend had a 91 305 TBI and he ran a 14.7 @ 93mph.
He had headers, 3" catback, Carb intake with TBI adaptor, 14x3 open element air cleaner with the K&N Xtreem airflow lid, LT1 cam, 3.42 gears, and a prom I made for him to remove EGR and the Speed Limiter.

If you still have the speed limiter on your car, you will have an actual top speed of 97 or so mph. Speedo will be reading 115mph at 97 I think.
So you'll need a prom to remove the speedo or get a 3.42 VSS gear for the tranny.

Dec 25, 2003 | 08:41 PM

TKOPerformance

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Joined: Dec 2003

Posts: 2,391

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From: Newark, DE

Car: '86 Camaro, '02 WRX, '87 K5, '67

Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder

Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed

Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00

I think you will see more like a full seond drop in your ET. I went from 2.73s to 3.55s in my Mustang and went from a best of 16.80 to a best of 15.99 with no other changes. That's also a bone stock restored car on skinny tires launching off idle and keeping my foot out of it through half of 1st gear.

It's probably the best mod you can make for the money.