Hey guys I have a 86' F150 4x4 with a C6 tranny that I just got rebuilt and 9" rear end running 4:10's. Will eventually have 35" tires. Right now I have a stock 351W HO with 170,000 miles. It runs great and I am happy with it, but I would like to start over with a fresh motor since I restored the truck. My neighbor has a 390 and two 429 motors just laying around and I could probably get one for either free or very cheap. The 390 would probably take less work to get going because it has ran more recently and the guy said that its a real screamer. 429's ran about +10 years ago, but I dont think that they are seized. I have three choices: 1.) Rebuild 351W and keep it in truck, 2. Rebuild 390, 3.) Rebuild 429. Either motor I choose will get a cam,headers,intake,better carb, and the heads ported and polished. What motor do you think is my best option? Best truck motor? Most power? Will be a daily driver with occasional trail riding and mud bogging. What will I need to swap in one of the big blocks?

 

If it were I, I would choose the 351W. 1. You have a larger and more readily available selection of aftermarket parts. 2. It would be an easier job, which wouldn't dampen your enthusiasm and would allow you a little more money to spend on power mods. There is always something that you haven't thought of when you start swapping engines, not to say that it isn't fun, but it can get a tad frustrating. Good Luck.

 

Also, you will be shopping for a new tranny with either the 429 or the 390. Bellhousings are different between all three motors.

 

351w all the way, the big ole fe blocks are a little much for todays gas prices

 

stick with the 351. they are easier and cheaper to modify than the other motors. plus the other motors will need new transmissions, because of the bellhousing. plus, think about this. SMOG. how easy would it be to get a 390 or 429 to pass the stupid smog laws these days? also, i believe the 1986 351 was fuel injected, so you would need to get the fuel injection for the other motors. and that wouldnt be very cheap. so i believe your cheapest and best choice would be the 351. good luck.

 

I would go with the 460. They have tons of torque and with the modifications you mentioned it would really move.

 

Sorry I meant 429 but they are basically the same.

 

If you like it fine now, why change? I'd keep my eyes open for another 351W HO and build it. That way you can keep running until you're ready for the swap. There shouldn't be any complications.... like getting another tranny. No adapting hassles and you'd be pulling out a good spare.... or sell it to pay yourself back for the 351 you bought for the rebuild.

I'd be HARD PRESSED to to change from something I am used to and happy with to go to an unknown with possible headaches. Surely a 351 can be built to make you real happy I'd also hate to take a good runner off the road and not be able to use it again until it was finished. Swapping like for like should be fun, fairly easy, and quick. - just my .02


Good Luck!

 

If you want big block type torque and power, why not go with a 351 stroker and you don't need to change much of anything. Summit sells 393 and 402 rotating assemblys for a little over $1300. Port your stock heads or go aftermarket and you are looking at 400 hp and 425 torque.

 

I'm pretty partial to FE's but it would just depend on how much money you want to spend and how much work you want to do. The easiest way would be the 351W route. If you went with the big blocks, I would probably put aluminum heads and intake on the 429 to get some weight off of that TTB front axle. FE's don't weigh as much as 429/460's but I would probably put an aluminum intake on it at least. You could put an aluminum intake along with aluminum heads and water pump and it would basically weigh as much as a stock 351W. If you have smog tests on your vehicle it pretty much narrows it down to the 351W. I know a guy that put a 390 into an 85 F-150. Let us know about the smog testing, funds, and how much work you want to do and we can go from there.

JC

 

u want a bigger motor? bore n stroke the 351 to a 384-385 or what ever Fords go to(im not sure only did a chevy 350 to 383) with a cam, crank, head and porting and forced induction/ better airflow and new 1000+ CFM carb man ull be set for anything!!!!!!!!!

 

while ur at it... put a shift kit in the tranny too... ull be soo much better off

 

First off if either of those 429 are a 4barrel, 71 or older its 365hp bone stock, good cr, good heads (a lot can be gained by a port and polish), good torque too. A simple rebuild along with a mild port and polish, little hotter cam, better intake (like an edlebrock performer, or something similar), about a 700cfm carb, and some headers.

Ideally the 429 is the BEST route for cheap power, as it already has a good 100hp over your H.O. (which were carb'b up to 87) if its a 4 barrel and 71 or older. Also there are as many performance parts for the 429/460 as there are for the 351, plus you can't really make a 640cu in hemis headed supercharged beast of a motor out of a 351w can you .

But if you heart is set on the 351h.o. (which will be the easiest way to go as no tranny swap is needed same with the motor mounts), be prepared to pay a bit more to get the same power as the stock 429, i paid 3 grand for a pro. built one that i have in my flareside (would've done it myself but we didn't have the time to do it), and it's pushing 350hp, but thats with a near stock spec 351h.o. cam (out of an 87), the power came from the extensive head work and 10:1 cr (still gets roughly 15mpg), but i would like to swap cams out for a more aggressive one (i want over 400hp), and a bit better intake for the different power band, and get the carb tuned (it runs rich). But i wish i would've had a 429 readily avaible for when the old 351w in my truck kicked the bucket.

I would stay away from the 390 as its going to be the most work, you have to fab up motor mounts, rig up a bunnch of lines, find an "older", probably move the tranny mount forward or backwards, but if you want to do go ahead its just something that i wouldn't really do.

 

Here's somethings to think about. Both the 390 and 429 have points and condensors wich can get a little old to be playin' with on a daily driver. Unless you convert them to a newer more reliable electronic ignition box set up. And that can costly. Not to mention changing tranny's and complete engine wiring harness. And dependilg on where you live you may not legally be able to run either of those engines in your truck due to inspection and emission laws. So you may want to check on that. It just maybe alot less hassle for you to just rebuild beef up your current 351.

 

Much easier to keep the 351