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08-06-2004, 04:30 PM
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#1 |
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Registered User
Join Date: Nov 2001
Location: Ft.Worth, TX
Posts: 35
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Rear end swap?
My truck is a daily driver. It has a 250 and a 4.11 rear end. The mileage is pretty lousy (about 13 mpg). I'm looking at accepting a job that would require me to drive 230 miles of highway a couple of times a week. The old girl is wound-up awful tight at anything above 50 mph, and this stretch of road is a 70mph zone.
If i were to swap to a better ratio (like a 3.08) would my mileage be significantly better or would it not make much difference. Thanks
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72 Stepside 250 w/ 3 on the column DFW area |
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08-06-2004, 04:35 PM
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#2 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
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A 3.07 gear would make it much more bearable on the road...like 2500 RPM at 60 MPH (or close to that) but IMO. you'll be lucky to do much better...maybe one or two MPG.
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08-06-2004, 04:38 PM
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#3 |
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Registered User
Join Date: Jul 2004
Location: Amish Wonderland of Central PA.
Posts: 31
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Mileage would improve but one thing you must consider is that you will have increased wear on your clutch. With a 3:08 ratio, it will take alot more rpm and clutch slippage in order to get rolling from a standing start. You could almost forget about starting on a hill.
A 3:42 ratio would be far more friendly.
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Dennis 68 GMC SWB Custom 1/2 ton, 2WD, 350 V8, PS, PB, 3-Speed, 3:08 12 bolt rear, tilt, tach, vac, cruise and more. . . . Last edited by dennis111; 08-06-2004 at 07:20 PM. |
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08-06-2004, 05:24 PM
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#4 |
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Young Gun wth Fast Inline
Join Date: Jan 2002
Location: Idaho
Posts: 1,475
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If he has a 4 gear granny i dont think he will have any problems with a 3.08 rear. I mean it will be sorta powerless at the top, but what does one expect. I would be surprised if your mileage improves at all, your pushing a small stock inline pretty hard at 70mph which is definatly doable.
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1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!! |
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08-06-2004, 05:47 PM
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#5 | |
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Registered User
Join Date: Jul 2004
Location: Amish Wonderland of Central PA.
Posts: 31
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Quote:
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Dennis 68 GMC SWB Custom 1/2 ton, 2WD, 350 V8, PS, PB, 3-Speed, 3:08 12 bolt rear, tilt, tach, vac, cruise and more. . . . |
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08-06-2004, 06:17 PM
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#6 |
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Fixing my 67, & loving it
Join Date: Jun 2004
Location: Bridge City, Texas
Posts: 524
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I am puting a 350 trubo on my 250.It has a 3.73 posi in it now. Would a 3.08 be to much for it?
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08-06-2004, 07:18 PM
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#7 | |
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Registered User
Join Date: Jul 2004
Location: Amish Wonderland of Central PA.
Posts: 31
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Quote:
You might miss the bottom end spunk though. I don't think I would do it if most of my driving was in town. If you are building a highway cruiser, I'd go for it.
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Dennis 68 GMC SWB Custom 1/2 ton, 2WD, 350 V8, PS, PB, 3-Speed, 3:08 12 bolt rear, tilt, tach, vac, cruise and more. . . . |
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08-06-2004, 07:37 PM
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#8 |
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Watch out for your cornhole !
 
Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
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I'd do it. I believe the relief of going from a 4:11 to a 3:07 will be very profound. It will drive like a different truck.
A 6 cylinder has inherent torque over a V8 anyway. I bet if you said you had a 283 V8, no one would say a thing bad about the swap. The 250 is not that much smaller, but it's an inline and they are torquier. I think you'll be pleasantly surprised. The Tx Firefighter Super Secret Project (TM) that's going to be debuted soon has a 250 inline 6 with a 2.73 rear gear.
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I'm on the Instagram- @Gearhead_Kevin |
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08-06-2004, 07:45 PM
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#9 |
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Fixing my 67, & loving it
Join Date: Jun 2004
Location: Bridge City, Texas
Posts: 524
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There needs to be a Firefighter group here too.
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