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Author Topic: Can a 400 be made to get reasonable gas mileage  (Read 8618 times)
junkyardjeff
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« on: October 23, 2015, 10:20:06 pm »

I have a 460 in my 66 F100 and it really likes the fuel so I was wondering if a 400 could be made to get reasonable gas mileage,many years ago I had a 78 F150 with a 351-M that had a rv grind cam that would get me around 16 to 18 on the highway so I was wondering what could be done with a 400.
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quickshift
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« Reply #1 on: October 23, 2015, 11:04:24 pm »

NO......stay with the 460 and research various builds and results.
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84Cougar,88HO,Eddy RPM/700DP, 1.7RRs, shorty's, 8.8/4.10s,T-5/Hurst Pro Billet, K/C clutch...bla,bla,bla

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junkyardjeff
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« Reply #2 on: October 23, 2015, 11:16:51 pm »

I thought the 400 would be a easier swap then a smallblock since I could use the existing trans,I am getting about 12 with the 460 and need to get better since I want to be able to drive it more. I was originally planning on doing some serious  and hauling with the 66 but picked up a newer truck to do that with so change of plans with the 66.
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« Reply #3 on: October 24, 2015, 01:14:15 am »

I'd look into what would be necessary to make the 460 more efficient. A modern camshaft matched with a well tuned carb could do wonders.

There is also the possibility of a overdrive trans. While none of the options are cheap, they would be effective.
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Doing more with less, or something like that.
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Outlaw Bill
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« Reply #4 on: October 24, 2015, 08:35:41 am »

Stay with the 460 the 400 will not have better fuel economy.
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blue04.5
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« Reply #5 on: October 24, 2015, 10:20:50 am »

Would a turbo help, or would that take mpg the opposite direction?
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knucklefux
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« Reply #6 on: October 24, 2015, 12:38:55 pm »

the last 351M i had any dealings with got about 8 mpg and was a turd.

an optimized camshaft, overdrive transmission (or manual, if not already equipped), and different rear end gears would be the key things to improve MPGs.
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David Claflin
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« Reply #7 on: October 24, 2015, 12:49:21 pm »

A local guy swapped a 400 for a 460 in his F350, and picked up mileage. He put a good timing chain set on first as the emissions 460s had the cam retarded pretty far. WIth a good intake, carb, exhaust and ignition there's no reason the 460 should make you want to swap it.
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junkyardjeff
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« Reply #8 on: October 24, 2015, 02:43:28 pm »

Its a mid 70s motor with D3 heads,performer intake and did have a Edelbrock 750 carb which got changed to a 600,I might have too tall of gears so I will be removing the 2.75s and going with 3.00s as I might be lugging it with the 31 inch tall rear tires and will see if that helps. Motor was rebuilt and since it ran better then a untouched 77 460 I did have I presume the timing was changed but I really have no clue on what was done to the motor and probably has a stock cam.
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Outlaw Bill
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« Reply #9 on: October 24, 2015, 05:45:05 pm »

New pistons with today's thin ring pack will also help to reduce friction and increase fuel mileage.
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TeamZmotorsports 25.2 outlaw drag radial stock suspension 1991 Mustang
Thank You to the following for their help
TeamZmotorsports
Marcella Manifolds
Schoneck Composite
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"Stupid is as stupid does", "You can't fix stupid"
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junkyardjeff
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« Reply #10 on: October 24, 2015, 08:23:06 pm »

Its a Jasper reman so its probably not what it could be.
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quickshift
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« Reply #11 on: October 24, 2015, 09:54:15 pm »

Its a Jasper reman so its probably not what it could be.

.....

Look here:    http://www.460ford.com/forum/index.php  or   http://www.460ford.com/forum/showthread.php?t=119213

If you explore the 460ford forum further ,you can find mileage builds as well.
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71 Comet, 289,351w heads,RR's,12.5 TRWs,ported torker/750DP, Liberty Top Loader (2.78), 9"/6.00s, tubbed,ladder bars,11.9xs@110 ..bla,bla,bla
84Cougar,88HO,Eddy RPM/700DP, 1.7RRs, shorty's, 8.8/4.10s,T-5/Hurst Pro Billet, K/C clutch...bla,bla,bla

Never shoot your mouth off unless your brain is loaded.   If you're not laughing...you're not living!
quickshift
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« Reply #12 on: October 24, 2015, 10:06:55 pm »

A local guy swapped a 400 for a 460 in his F350, and picked up mileage. He put a good timing chain set on first as the emissions 460s had the cam retarded pretty far. WIth a good intake, carb, exhaust and ignition there's no reason the 460 should make you want to swap it.
I did this on my 77 F-250 high boy when the 400 broke and then decided to replace the 360 in my F-350 flat rack dually. My 78 F-350 CC hauler came with 460 but the timing chain change, EDDY 750, re curved dist and Headman Elite headers really brought it to life.....and better mileage to boot.


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71 Comet, 289,351w heads,RR's,12.5 TRWs,ported torker/750DP, Liberty Top Loader (2.78), 9"/6.00s, tubbed,ladder bars,11.9xs@110 ..bla,bla,bla
84Cougar,88HO,Eddy RPM/700DP, 1.7RRs, shorty's, 8.8/4.10s,T-5/Hurst Pro Billet, K/C clutch...bla,bla,bla

Never shoot your mouth off unless your brain is loaded.   If you're not laughing...you're not living!
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