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Discussion Starter · #1 ·
I messed up the 4.10 gear in my car. What is the tallest gear I can get away with with my single plane and cam? I would like to run a 3.31 or a 3.55. Can I? Combo is as follows:

*289 casting 454 bored .030
Scat cast crank std rods and mains (new)
Scat forged rods std 6.135 length (new)
Forged Keith Black pistons for 10.1 compression (new)
*60204 Lunati hydraulic flat tappet cam (new)
*781 stock gm heads with a little clean up work and stock valves
Isky 8005A springs with Crane gold roller rockers (new)
*Holley strip dominator intake (used)
*Holley 800 DP mechanical secondary carb (factory refurbished)
*Std Petronix electronic ignition (new)
*1 7/8” headers with 3” collectors (on car now)
*2 ½” full exhaust 40 flow masters (on car now practically new)
*M-21 Muncie 4 spd (on car now)
*GM 12 bolt with 4.10 gears (on car now
 

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With the Muncie, I don't think you would want much less than the 4.10s. That's just my opinion though.

I'm putting together an engine with pretty similar specs to yours. Have you run the car at the track yet?
 

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FWIW, I have a buddy that is running a bored/stroked 455 with a 4 spd and 3.55s in a '68 GTO. I rode in that car. It felt just right. It also had ludicrous TQ from 1500 to 5000 too.:D:D
 

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Discussion Starter · #4 ·
My concern is the single plane intake. Running damn good now noisy lifters and all at least good enough to shear the bolts on the ring gear. I need to get back to at least a 3.73 to drop the spacer which is part of the problem for the bolts shearing in the rear......but will my setup like the 3.73/3.55 or will the single plane fall on it face until the revs get back up? Or I could get the thicker 4.10 gear which I would like to get away from if I can. Any more opinions?
 

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I don't know what the specs on your cam are, and I may be waaay off here, but I'd say that unless you're running a race grind with LSA of 108 or smaller, you will have enough powerband to run 3.55s with a single plane no problem.
 

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3.55's will work just fine behind your combo. Down the road when you get some extra cash get an rpm airgap or stealth dual plane.
 
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