Help me do the math. 4.88 gears

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trebor75

trebor75

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This is my current setup in my Duster.

273 Commando - 1965
Cam: Comp Cams Magnum 282S - 282/282 Lift 495/495 (solid)
Edelbrock D4B intake / Edelbrock 600 Performer Carb
Pertronix Ignitor & Flame Thrower coil
Hooker Headers
2.5" Dual Exhaust / Super 44 Flowmaster
8 3/4 - 3.55 - SureGrip
727 auto / Shift Kit
10" 3000 stall converter
B&M Quicksilver Shifter

I have acquired a 742 house with sure grip and 4.88 ratio. I have 14" wheels and hossier dot pro slicks. They are 26". Will this combo redline before the quarter mile? I have taken it to 7000 rpm before without a problem. Anyone tried my combo and had experience. It should be fun to drive around town also I hope. Thanks!
 
I'm sorry. I might have posted this in the wrong section of the forum. Feel free to move it if necessary.
 
The formula I used shows vehicle speed of 108mph at 7000rpm.
Are you sure you want to spin it this high?

BTW, I ran a combo similar to yours back in the early '70s with my 340 Dart Swinger. With a manual-shift reverse-pattern valve body in the 727 I was in 3rd gear by the time I got across an intersection.
Yeah it accelerated great but those gears will be a killer on the freeway - how do you feel about 4200rpm at 65mph?
 
trebor75 said:
This is my current setup in my Duster.

273 Commando - 1965
Cam: Comp Cams Magnum 282S - 282/282 Lift 495/495 (solid)
Edelbrock D4B intake / Edelbrock 600 Performer Carb
Pertronix Ignitor & Flame Thrower coil
Hooker Headers
2.5" Dual Exhaust / Super 44 Flowmaster
8 3/4 - 3.55 - SureGrip
727 auto / Shift Kit
10" 3000 stall converter
B&M Quicksilver Shifter

I have acquired a 742 house with sure grip and 4.88 ratio. I have 14" wheels and hossier dot pro slicks. They are 26". Will this combo redline before the quarter mile? I have taken it to 7000 rpm before without a problem. Anyone tried my combo and had experience. It should be fun to drive around town also I hope. Thanks!
Click to expand...

I had a similar set up, 70 340 4speed with 4.30 gears and 26" tires. Yes it was fun around town but it got old real fast trying to travel any distance.
 
I had an SS with these gears. It red lined at about 100 almost instantly. Fuel killed me. It also roared going down the freeway.
 
Thanks for the help and input. It's not gonna see much of the highway luckily, but I'm also not selling the 3.55 I have now. I've been looking on how the D-Dart Commando was set up and my combo is now not that far from it. I just want to play around a bit this coming summer and take it to the track with the 4.88 and see how it does. Then It's back to the 3.55.
 
I would post them for trade for a set of 4.10's. Going from 3.55 to 4.88 is a huge jump.
 
the old saying for a drag car is 3000 rpm @ 60 mph. Typically, a 4.88 geared car would use a 31" tire. You could fit a 9 x 30" tire in there and go with a 4.56 rear. I run a 4.30 on a 11 x 29" tire. Runs low 10's @ 128 mph; 6800 rpm

I think you would really like the 4.10 or 4.30 in that 273 car on a 28" tire!
 
If you're running much more than 105 mph, you will likely run out of motor before the end of the 1/4 with a 26" tire and a 4.88 gear.

I ran 4.88 gears in my last car for a while with a similar size tire, but it was trapping just under 102 mph at around 6700 rpm.

I'd recommend going to a taller tire...I have 28" tires under my Duster, no fitment issues.
 
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