302 vs 351
Cargo Master
Joined: Apr 2003
Posts: 2,408
Likes: 5
From: Parkesburg PA
I woud say not because it's bigger, but I've never owned one. If you want better gas mileage get an OD trans from one of the later trucks and leave the 351 to some hot rodder.
BTW what's bad? I had a Suburban that got 9mpg. My 86 F150 302 gets 13 - 14mpg. That's with EFI and OD (Auto).
David
BTW what's bad? I had a Suburban that got 9mpg. My 86 F150 302 gets 13 - 14mpg. That's with EFI and OD (Auto).
David
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
302s are more for hotrodders because its a hi rpm power maker. the 5.8 is more suited for heavy rigs because it produces torque lower in the rpm range. this is what improves fuel efficency because you dont need as much peddle to move and the motor isnt working as hard.
But bigcountry what have you done to try and get better mpg so far? when was your last tune up? whats the condition of the carb? what trans, tires , gears are in your truck and is this 2wd or 4wd?
But bigcountry what have you done to try and get better mpg so far? when was your last tune up? whats the condition of the carb? what trans, tires , gears are in your truck and is this 2wd or 4wd?
Senior User
Joined: Oct 2005
Posts: 449
Likes: 0
I had an 84 F-150 4wd with a 302 2bbl. carb., c-6 transmission. It got about 13mpg. around town. (not really town, but suburbs) I decided to switch from the 302 to a 351w and it never saw more than 11mpg again. The power was a little better with the 351, but not much. The only time it made much of a difference was when pulling a load, but I'm sure that was due to the higher torque of the 351. In my opinion, it was not worth the effort or the aggrivation. Keep in mind, both engines were kept to stock specs with no modifications.
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Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
to get better mpg a good tune up always helps. a 4bbrl carb/intake will also improve if you keep your foot out of it.
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Elder User
Joined: Jun 2004
Posts: 747
Likes: 2
From: Pelahatchie, MS
I've got an 86 F-150 4x4 with a 351W HO, a 600cfd Edelbrock, 31" tires, a C6 tranny, and a fresh tune up. It's running really good, and the last check said 9.8mpg. Mostly interstate driving on that tank, 75 mph. I'm not really happy with that, but I don't see how I can improve it...... It was barely doing 8mpg with the old Holley 4180 on it.
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
efi will always get better mpg then carb. if you can increase the vacum on the secondaries so they are harder to open on ya unless your really barred your foot. this may help as well. also running 75 even with your setup is gonna use more fuel anyway.