Well, it'll be slow, but here goes nothing.
I'm building this motor for pulling, and just the cool factor of the 300.

What are some performance things that will accomplish what I'm after here?
I'm a complete newbie to the I6's... Its going in a 78 F250 and the heaviest load I can think of pulling with it is a 15,000 lb hay trailer.
May have to ****** start a mid sized tractor but who knows...

Any help would be great.

 

I'd say it's a great choice of engine to build up for the work you're doing. If you're pulling wagons around the farm, hauling and such it's perfect. 15k is a lot of weight, the 300 will move it just not in a big hurry... I wouldn't suggest going on the highway with it. Most 3/4 ton pickups of those years weren't rated for that much weight. However running back country roads you should be fine if you take it easy. Truthfully a bone stock 300 six is about as tough and reliable as they come. Speaking from personal experience, they will take a tremendous amount of abuse. The one thing I have learned about these engines is gearing is a critical part of making them perform. IMO they work best with a manual transmission behind them, more specifically an NP435, BW T18, or T19. The 300 six coupled with an old cast iron granny 4 speed and 4.10 gears (especially in a 3/4 ton or heavier 4wd) is an unbeatable combination for farm work.
If you're doing a ground up rebuild I would start with a mild RV cam, it will give you better off-idle torque. Stock crank, rods, and pistons will suffice; go with good quality bearings and piston rings. For bearings I prefer Clevite, for rings I like either Hastings or Sealed Power... high volume oil pump is a must. You could do some mild P&P work on the head and gasket matching never hurts. One thing I noticed that really wakes up the 300 is breathing. Ditch the stock one piece single outlet exhaust manifold and either go with headers or a set of EFI manifolds, the EFI 300s used a 2 piece manifold set up it was a huge improvement over the old set up. For what you're doing I think I would go with the EFI manifolds over headers, simply because cast iron manifolds are more durable than headers. Another thing is to ditch the stock 1bbl carb for either a 2bbl or 4bbl, there are adapters to install a 2300 series Holley 2bbl on the stock intake. Some will argue that they don't help performance, I from personal experience say they do... the difference was night and day. The best way to go is with either a Clifford or Offenhauser DP aluminum intake and a 4bbl carb, but it's more expensive to set up. If you ask me inline sixes score really high on the cool factor. They're tough, torquey, and won't let you down.

 

I too would suggest a mostly stock engine. I had a modified one in the truck in my signature, and the stock one I have in my crew seems to be more driveable than that one. The first was more powerful, but the stock one starts better cold and has a smoother power band.

I would suggest keeping the stock log manifold, EFI exhaust as previously mentioned, hotter coil, and then just drive it.

Not sure what gears your axles have, but before spending the $$ to regear, try it first once you get the engine in, and then go from there. Also, converting your transfer case to twin stick will help with gearing on the farm. It gives you low range without 4wd.

 

It seems the 3/4 ton trucks with a manual trans more often got 3.55s, and the autos got 4.10s. My 77 F250 4x4 351m has the granny 4 with 3.55s, one of my buddies has an identical truck but with a C6; he has 4.10s.

 

Here's the kit I'll be purchasing soon (Hopefully! $$$) without the headers though : Offenhauser 6019-DPK

That kit along with a cam and some port and polish work and it'll be a real sweet pulling engine. As mentioned before, gearing is of utmost importance as well! 4 spd with the granny all the way!

 

Well guys.. I'm gettin lucky here... A lot of my chassis wiring, fuel lines, brake lines, and most of my suspention was gone through not too long ago and so far it looks like I'll be gettin torn into my motor soon!

Just gotta find me some dang motor mounts...

I have got to get me a motor stand so I can get it up off the tires its sitting on now...

 

There's a guy at Fordsix.com forum who you should talk to. I think he goes by Lazyjoe, or some name with 'lazy' in it. He has a truck for farm use, and hauls a huge hay trailer.

Good luck.

 

If you are just going for brute power and low speeds, please consider the clifford performance cam size 264. It still holds 2 world records to this day, and you get an average of 80% torque off the line. That mod with a minor manifold and upgraded carb, a slight exhaust modifcation(you can push all air you want in but if you cant get it out just as fast whats the point), also look into re-gearing, i have a 3.08 in my stock 95 EFI, it pulls like a bat at of hell. Dont even see a difference when i hit the gas. But i also do more highway with loads than hauling, i can pull roughly 8k on highway doing 65 and not be pushin more than 2.5k with od off of course. But with what you are doing, and if you are truly going to go all brute force with low speed and dont care about mileage or driving it so much in town, than go with a 4.56 ratio. My buddy has 5.12 front and rear on his truck and granted he cant go more than 80 without pushin 3k, he can beat most bone stock mustangs off the line to 50mph. But it all depends on the true application. I would go 4.53 just because it seems more practical because you will stay in the LOW rpm range on a farm with that load and not to mention with that cam mod they compliment each other as long as you stay in the low range. With the carb i would consider a 4barrel over a 2 barrel as long as you do the exhaust mod. from personal preference and experience i found clifford long tube headers to free up ALOT once i got rid of my EFI manifolds, 20hp and 26tq dyno numbers) and i also put 2.5" al way out back into 3.5" echo tips no muffler or cat, breathes like a champ but not legal in most states (noise and emissions).

If you have any questions just ask, but good luck!

 

I would be leery to put anything Clifford on my 300, other than headers and intakes. But internal parts--it's not going to happen.

A while back some of C's cams go out that the journals were not polished. They went through cam bearings w/in 30 minutes. And then the owner had a hard time returning them. C's 264 has low duration (206 @ .050") with relatively big lift (.485" IIRC). You can buy an Isky 262 cam, and put on bbc roller rockers and get the same numbers. And Isky is one of the top cam makers in the industry.

 

With the Isky can i get more power quicker with that 262 vs the 264? Im looking for pure off line power up to about 3k rpm range. Not looking to push 180 mph but still get up to 110 in less than 5.5 sec easily! Whould you recommend the pistons they offer or the chrome rings? or anything? and if not why and can you give me some recommendations?

 

Best compare the actual cam specs and not rely on the advertised numbers. "262 vs the 264" are advertised and mostly meaningless.

 

FWIW, the stock cam has 268 degrees duration. And it's sick retarded, like 10 degrees.

For a hay hauler the Isky 248 or Comp 252 is the way to go.

 

Not so much looking for a hay hauler but somthing that goes from 0 to 110 in less than 5 sec preferred, looking to drag 1/8th soon and i want under 5.5, doable but i need to do math. Which cam would you guys recommend?

 

I was at the NHRA gatornationals and I spoke with a comp cams tech and told him what I was doing with the truck (DD and work horse) and he recomended the 260 for me, I don't know yet. But I do know I like the comp techs, they were very nice and easy going when I met'em at the races.

 

"...somthing that goes from 0 to 110 in less than 5 sec..." In what vehicle do you want to do this in?