Increasing MPG in a 460 - 460 Ford Forum
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post #1 of 18 (permalink) Old 02-11-2008, 09:06 AM Thread Starter
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Increasing MPG in a 460

I have a F250 1978, it's taking around 6-7 mpg.
i don't know if its normal.

It has 4 BBL Holley.

any ideas on how to increase the MPG?
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post #2 of 18 (permalink) Old 02-11-2008, 09:45 AM
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Well 460 and the word econo don't go together. :lol:
I think there may be some getting better milage.
Holly carbs are not an econo carb. You might get better milage out of a stock carb or an Edelbrock carb.. Maybe a little different timming setting and drive it with a light foot ... All tho they may not get very good milage they are consistance (same milage loaded or empty)
Tim
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post #3 of 18 (permalink) Old 02-11-2008, 10:53 AM
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If you want better gas mileage, go to www.mpgresearch.com. Lots of interesting ideas from small mods to indepth internal mods. All depends what you're willing to do.
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post #4 of 18 (permalink) Old 02-11-2008, 11:05 AM
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Edelbrocks are "easy" but aren't known for being thrifty..

If one would bolt on my Cougar I'd use a Qjet properly built by a reputable builder. Small primaries and massive secondaries.

Yes, they came stock on some Fords in the early 70s.
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post #5 of 18 (permalink) Old 02-11-2008, 11:18 AM
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Several things you can do, providing the engine is stock and untouched. First, Advance the cam to zero or better if you can find a timing set that will allow 4 deg advance. Stock cams are severly retarded. Second, The Holley 4180 is jetted too lean jet up 2 or 3 steps. Stock 4180s should have something like 622 close limit jets, try a 65 in the primary. Check float level and power valve, try a 6.5 p/v. Third, recurve the distributor to allow more initial advance and centrifical to come in full at 2800-3000 rpm, taylor the vac. advance for your new curve and application. Do all the usual crap like tire inflation, rolling resistence, free flowing dual exhaust, etc. Do this and you should get close to 12 mpg or better. The above will only work for you if the engine is in good condition and has good compression, low leakdown.
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post #6 of 18 (permalink) Old 02-11-2008, 11:43 AM
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Check the floats on the 4180, when I picked up my '87 it too was getting about 6-7. Turns out the moron I had bought it from had timing set @ TDC and the floats were way way high, just pouring gas down the holes. After setting timing @ 8 BTDC (per emissions label) and setting the floats properly I jumped from 6.8mpg to 9-1/4, and I think there is still a considerable amount to gain...
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post #7 of 18 (permalink) Old 02-11-2008, 03:07 PM
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Put a two barrel on it such as a Holley 2300 series with a four to two adapter. Hey, at least you can stuff the little pedal to the floor and still be on two barrels only.
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post #8 of 18 (permalink) Old 02-11-2008, 06:03 PM
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Edelbrock carbs with electric choke are set up slightly leaner from the factory than those with manual choke. Lean at cruise is a GOOD thing so long as it doesn't misfire because it's so lean. That's the best way to get good gas mileage. Also inflate the tires to their max recommended pressure, make sure the alignment is good, make sure brakes aren't dragging, make sure there's lots of ignition advance at low throttle, and put in the straight up timing chain.

If they can get you asking the wrong questions, they don't have to worry about answers.
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post #9 of 18 (permalink) Old 02-11-2008, 06:46 PM
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Quote:
Originally Posted by beltfeed
Put a two barrel on it such as a Holley 2300 series with a four to two adapter. Hey, at least you can stuff the little pedal to the floor and still be on two barrels only.
Absolutly backwards thinking.

If you need a carb that would allow a 460 to turn 4000 RPM, your looking at a minimum of a 500 cfm 2bbl. So your looking at a 2bbl carb with a venturi and throttle plates the same as a 1050 cfm 4bbl.

Now, if you need 500 cfm in a 4bbl, you can get buy with 2 primary throttle bores that are capable of only 250cfm, and use a progressive linkage, and have the second set open only when needed and or about half throttle. So most of the time your pulling high velocity air through a much smaller passage, with better atomization and distrobution.

A 4bbl with a driver that can keep a steady foot, is going to be about 3 times more efficent than a comparable 2bbl.
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post #10 of 18 (permalink) Old 02-11-2008, 07:23 PM
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look into doing a 5 speed swap such as a zf trans. I have a 91 f350 dually and an efi 460 ext. cab and pull down a consistent 14mpg. never worse than 11 towing

the boss is back . I didn't know it ever left!
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post #11 of 18 (permalink) Old 02-11-2008, 08:16 PM
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Bone stock old & tired 1985 F250/T19 4-speed/3.55 Dana 60 over here; managing 12 mpg hwy. I think more is possible with some engine mods. And even more with a 5-spd.

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post #12 of 18 (permalink) Old 02-11-2008, 09:08 PM
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$

Just for discussion. I use a Holley 4160 450 CFM unit on my 468 cubic inch Ford 385. Very similar application to the topic. It runs OK, but ask yourself, how much time does your engine spend at engine speeds over 2500 RPM or less! If memory serves me correctly, the primary of a reasonable 4V carburetor (450 CFM to 600 CFM) is smaller than a 2V carburetor, lets say in the 350 CFM to 500 CFM range, hence improved gas mileage with the change to a 4V, all things equal! One thing that we should keep in mind, any F-Series, especially older models that are less aerodynamic, is like pushing a sheet of plywood through the air! IMO, trucks that are made to work, are not necessarily economical, relative to economics!

Dave.

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post #13 of 18 (permalink) Old 02-11-2008, 09:09 PM
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kim

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Posted: Mon Feb 11, 2008 7:46 pm Post subject:

beltfeed wrote:
Put a two barrel on it such as a Holley 2300 series with a four to two adapter. Hey, at least you can stuff the little pedal to the floor and still be on two barrels only.

Absolutly backwards thinking.

If you need a carb that would allow a 460 to turn 4000 RPM, your looking at a minimum of a 500 cfm 2bbl. So your looking at a 2bbl carb with a venturi and throttle plates the same as a 1050 cfm 4bbl.

Now, if you need 500 cfm in a 4bbl, you can get buy with 2 primary throttle bores that are capable of only 250cfm, and use a progressive linkage, and have the second set open only when needed and or about half throttle. So most of the time your pulling high velocity air through a much smaller passage, with better atomization and distrobution.

A 4bbl with a driver that can keep a steady foot, is going to be about 3 times more efficent than a comparable 2bbl.

Thanks for the math 101 class Kim.

Now I can explain a true and tested method for you. A few years back I put together a mild 355" Chevy motor for a full size four wheel Blazer. Crower beast hyd cam, headers, mild port work, etc. Turbo 350, 2400 stall conv, 3.73 gear 35" tire. Surely not a rocket set up for a 4000 pound plus truck. I ran a 780VS Holley, a 600VS Holley and a two barrel 350 Holley. Which one pulled the best, the 780. Which one got the best mileage the 350 two barrel by a long shot. The 350 could get 18 MPG average, the 600 got 14 and the 780 got 12 with the same driving style. Was the 350 2bbl a dog, not really and you could get 5 grand out of it . Being the truck would need more gear and or motor to stick you in the seat the small carb really didn't come in to play that bad. It could still lay down a nice 40' burnout with the two barrel. And pull a 5000 trailer at 75 with no problem. Now if you want to drive without ever opening the secondaries sure the 600 would get better mileage. But I prefer to get on the expressway at 60 not 40 by pushing the pedal down.
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post #14 of 18 (permalink) Old 02-11-2008, 10:52 PM
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Darn my "79 Motorhome (23 1/2")with a 460 makes 14mpg (at 60mph)when I'm not pulling the trailer as long as the wind isn't blowing ! Pulling the race trailer loaded the whole unit weights 21500lbs and unless I running late it will still get 8-8 1/2 mpg , running late to get to the track I've got the mileage down to 3mpg ( I'm the Tech director there )I'm swapping the motor out with a 545 stroker (TMD cheap $789 kit)with a set of ported D3's -226-234 dur@.050 .525-.553 hyd cam-1.73 harland sharpes-stealth 8012 and a set of 1 3/4 ceramic coated headers, it would be in by now but one of my bud's just bought a new DTS engine dyno and I've sort of volenteered a motor to play on it ,and I'm going, why not see what this puppy will make for torque ! 2500-5000 rpm
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post #15 of 18 (permalink) Old 02-12-2008, 05:30 AM
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Have a look at my F100s specs below under this post.

I run a 780 vac.sec. Holley with #72 jets in the primary side, I hav HEAPS of advanced dialed into my Mallory (about 12 degrees on the timing light from memory) and no vacuum advance.

And I get 19, yes 19mpg at 60mph - ok we use Imperial gallons here but that should still equal about 16.5 to 17mpg for a US gallon. (and yeah, it's 'only' a 429 I guess!!)

A long way from anywhere

'70 429
Isky 270 cam
Roller-rockers etc
Torker & 780 Holley
Headers
Petronics and Mallory ignition.
Shift-kitted C6
2.75 4-spider 9"
All in '55 F100
Top speed: 131mph
Best e.t.: 13.93
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