too slow 63
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Joined: Nov 2004
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too slow 63
I need some advice. I have a 63 f-100 with a 233ci motor and a 3 speed manual tranny. Most of my driving is at highway speed (60mph-70mph), the motor has to turn too many rpm to keep out of everyone's way. I have a 460ci (machine work is done, needs to be put together), a 400ci (needs rebuilt), a C4, and a C6. Would you suggest using one of these combinations, finding a 302, changing rearends? My concerns are fuel economy, (could I get 15mpg from the 460), the initial, the operating cost, drivability and reliability. Thanks.
Posting Guru
Joined: Jan 2002
Posts: 1,836
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From: Elizabethtown, PA
My first instinct is to look at your rear axle ratio (you didn't post what it is). This is the easiest solution to your problem. The automatics will all suck more gas as they have more drag than the manual. Going from a six to a 460 will also not help mileage. What you're trying to address is the rpm's you are turning at highway speeds. The slushboxes you have are both 3 speeds, so it's pretty much the same as the manual you have now. The only auto trans that will help you is something like an AOD that has a overdrive cruising gear.
I really think you are looking for a higher gear (lower numerical). Going from a 3.25 to a 2.73, for example, will lower your revs at 70 mph.
I really think you are looking for a higher gear (lower numerical). Going from a 3.25 to a 2.73, for example, will lower your revs at 70 mph.
Junior User
Joined: Nov 2003
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my 63 originally had a 383 rear ratio. changed it to a 350 ratio and was able to go at highway speeds at a reasonable rpm. I was going to raise it even further to a 300 ratio but i was never going to use it as a tow vehicle again either. for towing I wouldn't go with more than a 325 ratio, although I'm thinking that would still be too high. If I remember correctly, the 3:83 was the standard ratio for 63's.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
Mike, Folks didn't drive pickups over 50 when yours was built, (a different time all together) Your engine is small and sounds worse than it is. As mentioned the rear ratio is in the 3.75 to 4.10 range most likely. Swapping in a 3.50 rear will help things a lot and will be the cheapest thing to do as well.
The best bang for the buck would be to go to a 4.9 or 5.0L EFI with overdrive. The larger engines have a lot more power but need more oats.
John
The best bang for the buck would be to go to a 4.9 or 5.0L EFI with overdrive. The larger engines have a lot more power but need more oats.
John
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