I got a 78 ford f150 4x4 with a 351m in it, im looking to put a better motor in it, mine smokes pretty good on start up and until it warms up, im pretty sure its the valve seals, and most recently a ticking from the bottom end. Its hard to tell exactly where its coming from its where the motor and the tranny bolt up. I was wondering what you guys are running in your trucks.

 

Well, new pistons and a crank will get you a 400M or you could swap in a complete 460. I have a 351M in mine, but I've thought about going to the big block since its not my daily.

 

why not go with a 351w that is EFI? Good reliable power, better mileage with efi, and readily available

 

thats a pretty loaded question. I as well have a puffing 351m. that i would like to change. Its all in how you use it.. how it will be built what your looking for it to do and how deep your pocket is. isn't there a quote here somewhere.. speed is a question of money.. how fast do you want to go " or something resembling that. haha. half ton 4x4 you say.. do you have a really heavy foot.? whats your transmission? that may hinder you in what you build.. although i think you'd be a big block C6 or bell housing. ( correct me if i'm wrong someone ) if you want a nice stout 302, you can get cheap power from them... or do a mild build on a big block and have moderate hp but way more torque for cheap. but you pay at the pumps. If built correctly all ford motors are reliable. ( hehe ) I like the idea of an FE block but 460's are tempting.. a peppy 302 will be cheap an plentiful for parts. sky's the limit.

 

Hey southern boy, you truck sounds exactly like mine...puffs on start up, but my motor has a 650cfm holley 4bbl, performer intake, hedman headers, and recently put a straight up timing chainset in it! and wow that chainset was like adding a 100 hp! i didnt think a measly 351ci could move 6500lbs like that! I plan on (during spring break) rebuilding it with a new 400 bottom end..and a nice comp cams high energy cam to wake her up even more. I think you should go the route im going, because a 400 without smog junk is almost has the same power to weight ratio as a 460...but with less weight so youll also have better handling, and you wont have tranny mating issues, motor mounts...etc. Its much easier to upgrade your 351m than it is to throw in a 460

 

i would drop in a big block thats what i did in 78 after the my 351m stacked the main bearings on top of each other.... L&L Products sell complete kits for what you need to put big blocks in your truck

 

I have a c6 behind the motor, im looking for some power. I dont mind about the gas money, i plan on putting bigger axles under it, and eventually 38 swampers. Whats this straight up timing set ? Im looking to keeping the same tranny, but at winsor is very tempting. What all engine sizes will bolt up to the c6 housing? I wouldnt mine keeping the original motor, and punching it out to a 400. I just dont know if it worth it in the end. Ill have some money to spend on a motor.

 

351M --400--460 ,the same .I put a 460 in place of the 400 in my 79 bronco.It had more power and handled better. Fuel usage was the same with the 460 ,holley 4/b as the 400, 2/b,but better performance. I used the 400 motor mount towers by making an adapter plate between my 460 block and some mid 60s 390 passenger car motor mounts. I have a 460 in my 79 F-100 ,doing the mounts the same way on the 302 mount towers. Cost was allmost nothing using all new parts.They held up 10 years on the bronco before I removed them and put them in my f-100. Or you can spend money for a change over kit if that works the best for you.

 

just put the 460 in you will be glad you did why bore and stroke a 351 when you can drop in a 460,now you can go from mild to wild

 

460 for sure. Bolts right to the existing trans and is one of the best mods I have done to my truck.

 

I agree with many others, do a 400. If you want a high horsepower with higher compression, use 351 C pistons with bushed 351M/400 Rods on a 400 crank.

429/460 are great engines, but heavier and then you have engine mounts and accessory mounts to find and exhaust to work out.

351C or 351 W will require transmission change.

In 1992 I had about 75K on my '77 351M, it was October, I was going to drive near 600 miles to visit with wife's brother and family in Ga., see the King's last race at Atlanta, and pick up a ShopSmith MkV and so I took the truck, loaded up the wife and puppy, and off we went. Noticed oil gage was low, but had oil, and no noises so I figured sending unit shot. Down in Chatsworth I stopped at a NAPA and grabbed a unit. Drove on to BIL's at Carrolton.

Installed sending unit after unpacked and settled in, and on Sunday we drove the truck across back roads to the track and watched Alan Kulwicki win the chjampionship, Bill Elliott win the race, and Richard have a fiery wreck early on but re-enter race later ... than back to BIL's house.
Oil gage still low so figured gage was bad as no lifter noise, motor was quiet.

Monday, loaded up, loaded up the SS MkV and accessories, said good bys, headed home. Went up through Ellijay and across Brasstown and through Nantahalla and then up across the Smokies hitting the Va. line after dark and then set cruise on 60-63 and come up 81 getting home near midnight.

Tuesday I unloaded everything and then drove to buddy's shop to see if he had a spare manual gage I could borrow. He did, I hooked it up, I had 4 psi oil pressure. Oh Crap! I tippy toed home afraid I would hear a knock any sec.

Pulled around back, set front tires up into two steel wheels, then raised truck and dropped panhard rod and oil pan. Pulled one main and one rod and crank was good .... but top of rod shell was worn and bottom half of main was way thin into copper.

Went to NAPA, miced them on the side, looked in book, had STD bearings. New rod and main bearing shells in hand and a new pan gasket and melling hi vol oil pump and went home. Machinist (Brownie) asked how many miles, I said 75 thousand, he said it was due on a 351M.

I replaced the shells one by one at a time, each pair, front to rear. Worst worn bearings in my 351 were the mains closest to the front, I remember I could move the crank up and down some by grasping the harmonic balancer.

I was just hoping to get a year or two out of it. Here it is 18 years later, but only 27,000 miles later, hot she runs steady 60 psi on a manual gage hooked up with a tee so stock works too.

We've talked about it since, and he said most 400s didn't do it for some reason, he didn't know why. I think it's a balance issue myself.

I got me a good 400 within a few months then and it's on the stand in the basement now, block is done, cleaned,, crank polished, new bearings and rings and pistons and freeze plugs, painted pretty Ford Blue.

When I swap it, if I don't sell it first, I'll use the heads off the truck because I had just replaced them too prior to that trip due to a burnt valve I caused in trying to lean out the carb to improve gas mileage .... went too lean. I was building my house then and needed to swap heads fast so I got a set off a T-bird 351M and they have 16 new guides and 8 new exhaust valves and with only 20 some thousand, should be good to go with just a good cleanup.

I stopped trying to get better mileage, just fattened the jets back up on the 1850.

Sorry .... got carried away ..........

 

tbear853, my 351m was the same way. I figured there was no way the oil pressure gauge was working. But when the engine was completely cold and I revved it, the gauge would BARELY move. I'm talking like 1/64 inch! When warm it did not move at all. No engine noises either. I swapped it out when I found almost no compression on one cylinder.

My uncle has a 78 Ranger that he bought in the 80s. Its a 400 so they did do it as well though maybe not as often? Him and my dad were well aware of the oil pressure problems so then went on a very long test drive to get it good and hot. The oil pressure stayed good. Well the ride home was like an hour and when they got home there was no oil pressure. He installed new main and rod bearings with a high volume oil pump. And close to 25 years later he still drives and it still has great oil pressure.

 

Hmm decisions, thanks to everyone for all this good input.

 

I'd say keep the 335 series in there, with a 400. Dollar for dollar, you can essentially match a 460 until you start talking strokers...then it's 460 all day. If match a stock 400 to similarly equipped (smogged) stock 460, you'll notice the the 400 has right at 90% of the hp and torque as a 460. Desmog them, and the difference remains constant. Add equivalent parts and you're still talking the same gap. Difference is, the 400 does it lower in the rpm range...which is where you want a truck. Most of this info has been posted on Project Bronco, Bubba's M-Block, or TMI's site, or he's posted dyno charts. Honestly, I don't see many of these trucks going past 3-400hp for a street rig. IMO, on a 6000# rig, 30hp isn't that much of a sacrifice. And if your area is anything like mine, everyone thinks their 460 is gold and bad engines start out at $500...so figure that in to your costs, where as I can pick up a 400 from free to $100 all day. On top of that, my 460's have always gotten 8-10mpg's, and my 400's have always gotten 10-14mpg's. Now you say you don't buy these trucks for mpg's, I agree...but I'm a numbers/money guy and the 460's just don't make economical sense to me.


But that's just me, I always support the underdog and protect the red headed step child.

 

Depends what you want or need.

351W or a 351W-based stroker. Great bang for the buck and really good aftermarket support.

A 460 if you haul or tow alot.... FE generally means "freaking expensive".