I have the opportunity to buy a f-150 from a friend that would come with a 351w(currently not in truck). I am looking for opinions on what I should do, build a 347 stroker using the 351's crank and getting a 302 bored .40 over, or rebuilding the 351w with headers, intake, and mild cam? Which one will get better mpg, the truck has 35s on it, I would like to put a 4 or 5 speed with overdrive behind the engine. Also, would a pair of 2bbl carbs work and get good mpg if they were on a progressive throttle linkage?
Brett

 

first you can't use the 351W crank in a 302 ....


go with the 351W then stroke that to a 393 408 or a 427..... it's a truck you need cubes...

 

351 wins here easily. There's no way you can build a 347 for anywhere close to what a stock rebuild of the 351 will cost, and the 351 will easily outlast the stroker. With an HO cam, 9:1 pistons and 4bbl carb you'll have a fine truck motor for a couple hundred thousand miles.

 

look into a zf 5 speed manual to swap in as well and get some gears like 4.56 or 4.88's to handle the tires.

 

351 for sure for reasons already mentioned.

 

ZF is hard to find...and there ain't nothin wrong with an M5OD...

JR

 

your joking right. the m5od is ok but not worth placing behind a 5.8 if you tow or plan to wheel it hard. everday driving would probably be ok though.

ive seen 300-6 and 302's eat the m5od so i can just imagine what a 5.8 would do.

the zf can be found in f250 & F350's , just get one with a small block bolt pattern.

 

Since it's already coming with a 351w, I'd use what you got. That'd be a good base to start with. Not that a built 347 stroker wouldn't run just as good as a built 351w.

 

What kind of mpg would I get with the 351w if I did headers, 2.5 exhaust, single plain intake, mild/rv cam, and a 4bbl carb(500-600cfm), or could I get better mpg with a pair of 2bbls?
Brett

 

With 31" tires and 3.55 gears?
Brett

 

No I'm not kidding...a buddy of mine has a 97 F-250 with the Mazda...it was a auto to manual conversion....he runs 36 inch humvee tries with factory gears and he wheels her pretty good...still puts up to the abuse...same as the 94 Bronco on 40 inch groundhogs and a severly modded 351w RV motor...

JR

 

Once you setup the carb or carbs with the appropriate jets for the motor's demands, it'll use the same amount of fuel. In other words the carb does not determine the fuel consumption, the motor does. For milage expect single digits offroad, 10-12mpg around town, and maybe as high at 14mpg at moderate hwy cruise speeds.

 

Not at all. 347 will out perform a 351w. Even with the cheapest stroker kits available the 347's rotating mass is 15-18 lb's lighter. Remember your physics Force=Mass*Acceleration or A=F/M

Reduce the denominator (Mass - 25-33% lighter in 347) the second equation and watch your acceleration ramp up. Not to mention the huge bearings in the 351w.... lots of frictional energy lost there.

As for reliability of the 347. This all comes back to the assembler. Oiling issues = poor assembly. Wrist pin blah blah...

Check these links :

1. 351 w vs. 347 based stroker

http://sbftech.com/index.php/topic,7864.0.html

2. 347 vs. 331

http://sbftech.com/index.php/topic,6087.0.html

 

^I don't know if you are disagreeing with me or not. I said it would run just as good. I would have said 'would run better' but boy, wouldn't that start a flame war with the 351w guys. They, fairly, have the arguement that you can 'stroke the 351w, too'.

But, since he already HAS a 351w, it'd be much cheaper to just go ahead and build it with the parts he mentioned for a good, torquey engine.

I am somewhat partial to the 302, and I know a 347 stroker is a bad *** engine.

But, again, I dunno if I used bad wording or not, but I didn't say the 351w would be 'better' than a 347 stroker.

 

Would 3.55 gears be good enough for 35s? I think I'll stick with the 351w, but that still leaves me with the issue of figuring out what carb setup.
Brett