dirtcrew51m

302 tired, looking at a 351w, also hoping to convert to mass air, staying auto trans, is there any difference in power and mileage compared to the 302? If I can get a little more power with basically the same mileage, I would be happy. Or just redo a 302 and leave it. This is not a daily driver I just use it when I need it.

fircatfanatic

my 351 has cams with a 4 speed behind it but it pulls 10 times harder than my 302 auto and gets apprx the same gas milage

Oldrusty

When I replaced my 302 with a 351,I gained almost 2 mpg and a noticeable power jump. You will also want a computer for a 351 that also matches your tranny,and a flexplate for a 351.

dirtcrew51m

Thanks. I might have a 351 lined up, also a maf harness.

waih136

What are you guys getting for mpg's? I"m only getting 8-11 with my 96 351 and i know that's low. Still has wicked power though and all i've really done is add k&n filter to it

dirtcrew51m

I dont use it that much so the mileage isnt a real concern, but I like the power of the 351, I really want a 460 but then I would have to find a trans and the frame mounts, unless I can find a donor cheap, the 351 would bolt right in.

Oldrusty

Last time I checked it was almost 16,thats with it loaded pretty heavy.

nemesiss45

7.6 mpg last time I filled up... but I'm still working through some issues... she'll be doing better when I am done.

Mass0wnage

I hope you got Major issues! Really hope when I get done putting this 5.8L together in my 93(swappn a 5.0 out) that my mileage don't suck like that!

Leaving the smog pump out so yeah, prolly gonna blow lol.

nemesiss45

Well, the thermostat was stuck open, which, if I understand correctly, would have been making it run extra rich, so that should help already... and since I don't know how long that was going on before I got the truck, it might have boned the ox sensor and cats... I don't want to spend money on new cats, but at least I could go high flow if I have to replace em.

I'm not expecting too much... my father in law has had a 5.8 forever, and he says he's always gotten 10-12

I'd think removing the smog pump would gain you some mpg... but I've heard it will ruin your cats eventually.