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gas mileage

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Scott2

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I'm going to be replacing the original rearend in my truck, and am looking for some advice on the best gear ratio. I have a 350 v8 in it. basically I don't want to loose any of the "get up and go" it has but want to save on gas mileage. What would be the best gear ratio to get. I'm going to mostly be traveling around town but sometimes be travelling on the highway. I would be willing to give up the "get up and go." If I do have to do that what can I do down the road to the engine to get the "get up and go" back. Thanks a lot for the help.
 
It's a 3 speed and I'll try to find out what it's geared. It does have the original rear end in it though. I just know it's turning far to many rpms and gets about 12 to 13 miles to the gallon. my tacometer is broke so I can't give any specific rpms at a specific speed.
 
Not to disuade you from your plans, BUT,,

I think you can get exactly what you want by swapping to an overdrive transmission and staying with the rear ratio you have now.

I considered the same rear end swap, but was convinced to do a 700 R4 swap instead.

I went from a granny 4 speed with 3: 70 rear getting 6-9 mpg ( with a tired 305) to getting 12-16 mpg with a crate 350 and 700 r4.

What is nice about this setup is that 1st gear launch is about the same as it was with the 2nd gear launch of the granny. Getting on a freeway is a joy. Hit the ramp, get up to speed in no time, and with electric lockup, goes into overdrive smoothly above 44 mph. It reduces the engine rpm by about a third. The average engine RPM stays constant at 1500-1800 when driving normally on surface streets to about 1200 crusing at 65.

You get the best of both worlds, good launch and around town driving and low rpm crusing at freeway speeds.

DV
 
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