400 cid Fuel Mileage - Ford Truck Enthusiasts Forums



1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck

400 cid Fuel Mileage

Reply
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 02-28-2011, 09:34 PM
hunterlee15 hunterlee15 is offline
New User
Thread Starter
 
Join Date: Dec 2010
Posts: 4
hunterlee15 is starting off with a positive reputation.
400 cid Fuel Mileage

I'm looking at a 1979 F150 4x4 for my 16 year old. It only has 47,000 original miles on it, but it has a 400 with a 4 spd and I am concerned about the mileage it will get. Would swapping the 400 for a 351 or 302 improve the mileage noticably? Or is there maybe another route to go to improve the mileage, i.e. changing trans? When he's older and can afford the gas, we could always go back to the 400. Thanks for any suggestions.
Reply With Quote
  #2  
Old 02-28-2011, 09:37 PM
Vinford's Avatar
Vinford Vinford is offline
Postmaster
 
Join Date: Aug 2004
Location: Williams Lake B.C.
Posts: 3,234
Vinford has a good reputation on FTE.Vinford has a good reputation on FTE.
Quote:
Originally Posted by hunterlee15 View Post
I'm looking at a 1979 F150 4x4 for my 16 year old. It only has 47,000 original miles on it, but it has a 400 with a 4 spd and I am concerned about the mileage it will get. Would swapping the 400 for a 351 or 302 improve the mileage noticably? Or is there maybe another route to go to improve the mileage, i.e. changing trans? When he's older and can afford the gas, we could always go back to the 400. Thanks for any suggestions.

If your worried about fuel your buying the wrong type of vehicle for him.
Reply With Quote
  #3  
Old 02-28-2011, 09:55 PM
JustBlaze's Avatar
JustBlaze JustBlaze is offline
Senior User
 
Join Date: Sep 2010
Location: Upstate NY
Posts: 241
JustBlaze is starting off with a positive reputation.
I doubt a 302 or 351 would get better mileage in a 4x4. They would have to work harder. The 400 makes a ton of torque down low and that helps with mileage.
Reply With Quote
  #4  
Old 02-28-2011, 10:58 PM
cowboywanabe's Avatar
cowboywanabe cowboywanabe is offline
Exiled South Dakota CL
 
Join Date: Nov 2001
Location: Grapevine, TX
Posts: 36,229
cowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputationcowboywanabe has a superb reputation
My truck has the 400, it was rebuilt, has about 12,000 miles on it... The best I've gotten was 12mpg on a 200 mile trip across Nebraska. No wind, it was summer time, and I stayed under 65mph. The engine is stock except for the edlebrock intake and 4bbl.

I don't keep track of the mpg's when I'm running around town.
Reply With Quote
  #5  
Old 03-01-2011, 08:49 AM
Fat&Bald Fat&Bald is offline
Senior User
 
Join Date: Feb 2004
Location: VA
Posts: 185
Fat&Bald is starting off with a positive reputation.
My 78 F250 (400\4 speed\Edelbrock intake with Holley 4 barrel\4.10 gears) typically got 10-12 mpg around town or highway, with a load or without. The gas mileage dropped off at speeds higher than 60 or so. You will not likely improve the gas mileage by going to a 302 or swapping the trans to an AT.

I've recently swapped to a Q-jet on a rebuilt 400 with a different cam so I'm hoping for an increase in mpg but even then it may only be a couple mpg.

A high school kid with little income is going to have a hard time keeping that truck on the road.
Reply With Quote
  #6  
Old 03-01-2011, 09:06 AM
MikePacey's Avatar
MikePacey MikePacey is offline
Elder User
 
Join Date: Dec 2010
Location: New Carlisle, Ohio
Posts: 585
MikePacey is starting off with a positive reputation.
If you put on a straight up timing set and headers with dual exhaust you'll see a mileage increase not sure by how much. What is your rear gear ratio? 3.54? 4.10? If you run a 4.10 run a big tire to lower the overall gear ratio. Or just swap to the 3.54. The more volumetric effiancy your engine gets the better mileage you will get since your engine is working less. swapping cams to one a little bit bigger then the stock one will help. Running like a little 600 cfm 4bbl vaccum secondary carb will help because you can adjust it better. And the vaccum secondary helps because you will run on the two front barrels till you stomp on the throttle. Lighten the truck up. For every 100 pounds you lose you gain 2% in fuel mileage.
Reply With Quote
  #7  
Old 03-01-2011, 09:12 AM
ibleedblue1385's Avatar
ibleedblue1385 ibleedblue1385 is offline
Posting Guru
 
Join Date: Mar 2006
Location: Parma, MI
Posts: 1,213
ibleedblue1385 has a great reputation on FTE.ibleedblue1385 has a great reputation on FTE.ibleedblue1385 has a great reputation on FTE.ibleedblue1385 has a great reputation on FTE.
Quote:
Originally Posted by JustBlaze View Post
I doubt a 302 or 351 would get better mileage in a 4x4. They would have to work harder. The 400 makes a ton of torque down low and that helps with mileage.

What he said. Assuming the engine runs smooth and clean you should be in the 10-12 mpg range.
Reply With Quote
  #8  
Old 03-01-2011, 12:37 PM
hunterlee15 hunterlee15 is offline
New User
Thread Starter
 
Join Date: Dec 2010
Posts: 4
hunterlee15 is starting off with a positive reputation.
400 cid Fuel Mileage

Thanks for all the feedback. Some pretty good food for thought. May leave this truck in the garage for a build myself later on!
Reply With Quote
  #9  
Old 04-15-2016, 07:54 PM
30odd6 30odd6 is offline
New User
 
Join Date: Apr 2016
Posts: 1
30odd6 is starting off with a positive reputation.
unbelievable milage for a 400

I know this was years ago, but I just signed up. as for fuel mileage with a 400, I was just amazed at what I made mine get. I have a 78 f150 4x4 with granny gear powered by a true stock 400 with a 2150 2bbl. i decided to see what I could squeeze out for mileage with the motor running at optimal power (never go lean! I know that robs hp and mileage, not to mention harming the engine). I have opened the exhaust to 2-1/2" with mufflers as far back as possible, did away with most of the vacuum, set timing to around 12btdc initiallly and checked total timing to 34btdc and adjusted vacuum advance with the 1/8" allen inside to coincide with how fast it gets there ( I ended up with 15btdc at idle), carb overhaul and tuned by vacuum (which is about 21psi, I went back and forth with timing and vacuum). anyhow, I ended up getting 17.987 mpg!!!! and still have the horsepower to not use a chainsaw....just hook the chain to a tree and pull the whole f$#ker out!!! lol . one added thing, because it was a test, I know these engines loved leaded gas, so I used 91octane and added a bottle of 104+. so, if everyone keeps saying that you can ony get 8-10mpg, they havenet worked hard enough to get the 18mpg....even without the 10-4+, I will get over 15mpg....I LOVE MY TRUCK !!!!!
Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
A quick mileage question. cowboyacg 6.7L Power Stroke Diesel 8 10-10-2016 03:14 AM
what gears for a 400 c6 half ton. youngone1234 1973 - 1979 F-100 & Larger F-Series Trucks 4 09-03-2016 05:48 AM
plastic timing gear in 400 WHRAVEN 335 Series- 5.8/351M, 6.6/400, 351 Cleveland 6 07-23-2013 08:34 PM
6.9L diesel in my 1980 Bronco? ErrorS 1978 - 1996 Big Bronco 10 06-22-2010 12:20 PM
351/400M Gas Mileage fe4ever 1973 - 1979 F-100 & Larger F-Series Trucks 2 01-22-2001 01:49 PM


Go Back   Ford Truck Enthusiasts Forums >

Tags
1979, 400, 400cid, 4b, carb, cid, f250, ford, fuel, gas, gasoline, lifted, location, mileage, milelage, modular, mpg, type

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump


All times are GMT -5. The time now is 11:21 AM.


This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.