All Big Six 300 build for towing 12k lbs

Relates to all big sixes

BigBlue94

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An axle swap is definately something i want to do as the dana 70hd is kinda an odd ball. Only one option that i could find for a limited slip/posi.

Also im new gearing. But i feel with out even towing that the gearing should be different. Maybe its just the t18. Im set with my new tire size. would that play into choosing different gearing? I think its the stock tire height
There is nothing really wrong with the D70. Axle tech hasnt changed much since GM introduced the full floating rear axle in the 1930s. Bearings and seals and material quality are where the advancements have come from. The D70 has a 10.5" ring gear, just like a corporate 14bolt or Sterling. But its older tech.

I have an np435 in my bronco that is basically the same as your T18. Being basically a three speed plus granny gear, the gear splits are larger than a 5 or 6 speed. This means you cant always keep the rpms right in that 3000 to 3500 sweet spot. With stock tires of about 31 inches, a 4.10 to 4.56 gear would be what i would choose. 4.10s will give you a slightly higher top speed but less grunt.
 

THE FRENCHTOWN FLYER

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3000 to 4000 rpm is where you need to operate the engine in order to pull the 12K load up a grade or shifting through the gears to accelerate up to speed. The goal is to move peak torque just above 3000 rpm to make the horsepower needed to get the job done.
The engine build I described above makes power from 1000 to 5000 rpm with over 300 ft lbs of torque.
If that be the case I wish to retract my suggestion to advance the stock cam. Leave it where it is and concentrate on my other suggestions.
 

pmuller9

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Thanks for all the input guys! I appreciate it.

So a cam, gear swap and brake upgrade seem to be in order.

Ill just run my motor till it quits, which might never happen.. lol. I recently started using 15w40 oil. A friend recommended using it as i thought i was getting some blow by. Also i put some lucas in there. But after installing the new yfa I think it just dumping an ubsurd amount of gas the whole time. No more blue smoke.
You originally wanted to know where the weak areas of the engine were.
The stock pistons are the weakest link.
The piston skirts break off into the oil pan but the engine will continue to run until the piston crumbles.
Broken 300 piston 2.jpg

We highly recommend replacing the stock pistons with Hypereutectic pistons as part of the engine rebuild.

Stock connecting rods resized with ARP bolts are sufficient.

In order to get the torque moved above 3000 rpm the cam change needs to be accompanied with a ported big valve cylinder head.
Finding a second engine to build and swap out later would be a good idea.
 

fox81

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You originally wanted to know where the weak areas of the engine were.
The stock pistons are the weakest link.
The piston skirts break off into the oil pan but the engine will continue to run until the piston crumbles.
View attachment 8889

We highly recommend replacing the stock pistons with Hypereutectic pistons as part of the engine rebuild.

Stock connecting rods resized with ARP bolts are sufficient.

In order to get the torque moved above 3000 rpm the cam change needs to be accompanied with a ported big valve cylinder head.
Finding a second engine to build and swap out later would be a good idea.
Ok this is the stuff i was looking for.
I will do this for sure.
Im having a hard time finding an extra motor in the seattle area. Im looking into a crate motor maybe from jasper but Id prefer have control over what goes into the build.
 

bubba22349

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I did essentially what you want to do the old school way back in the late 1980's with a almost stock 300 rebuilt to Medium duty specs. Below is the parts combo I used for my 300 swap in a 1965 F-350, it was a real workhorse that could haul heavy loads, tow trailers effortlessly, and it never let me down. I had another 300 six in it that replaced the original 240 Six it was just a budget ReRing it wasn't in the truck very long just a few weeks before I lost that engine when one of the stock Ford cast pistons came apart at 62 MPH so yes X3 don't leave those 1965 to early 1995 cast pistons in your 300 short block if your planing to work it hard. After that experance I built the 300 six below and also every other 300 six there after at least got a new set of aftermarket cast Pistons.

The Short block build was a basic .030 over with aftermarket rebuilder cast Pistons (I used a NAPA sourced Master engine Kit and their machine shop services in Visalia, Calif.) est. compression was about 8 to 8.5 to 1, upgraded the kit to Molly rings, .010 / .010 stock cast crank with an upgrad to Cleveite 77 bearings, rebuilt stock connecting Rods, Melling (standard pressure) oil pump, stock 1965 F-350 6 quart deep oil pan and oil pump pick up tube off the orginal 240 six, stock bearing clearance's, upgraded Melling (MTF-6 RV / Torque) Cam, Aluminum Cam gear / steel crank gear, FelPro gasket set. The final head that I ended up with was off a 300 propane fork lift engine (with stock valve sizes Serdi radius valve seats with 3 angle grind to valves and back cutting). I found this head to use as a replacement when I was having trouble with the two previous early head castings (1965 to 69) that kept wiping out a couple of the exhaust guides this when California took all the lead out of the fuels. I used the stock log exhaust manifold into a 2 1/4 inch pipe and a single turbo muffler dumping right in front of the passenger side tire. Stock intake with a new Holley 1940 carb, the Ignistion was a stock DuraSpark II system and stock wiring harness from a 1977 up Ford 300. The engine performance was excellent for hauling or towing, it ran great on 86 - 87 regular gas and it's pulling torque started from just off idle. Some other things that I wanted to try out on it back then, was using one of the big truck (heavy duty) exhaust manifolds from an F500 / F600 with a full 2 1/2 inch exhaust system, one of the rare Eldenbrock 1V intakes, with a 1968 Autolite 1V and also one of the Carter YFA carb's, (I was going more towards MPG economy). Also planed to try a Brown Loppe 3 speed Aux. Trans (0ver and under) or better yet a gear venders overdrive unit behind the 4 speed trans. If I was building it today would also do some more to the head by pocket porting under the valves and do some mild porting to clean up intake and exhaust ports. This engine build was done for a reasonable cost and was very economical to operate develering 11 to 15 MPG depending on the load being pulled or carried.

About the truck.
The truck was a 1965 Regular Cab F-350 base model (no frills or extras other than a heater) short wheel base Dually Chassis with a 9ft x 7ft stake bed with a dump, stock cab fuel tank & an extra 18 Gal saddle type fuel tank, weight was just a little over 5800 Lbs with fuel and truck bed empty, had the excellent NP435 trans and a Dana 70 rear axle with 5.13 gears. The truck was originally equipped with a 240 six so the gearing was just a bit too low for the extra torq of the 300 that I swapped in it a set of 4.88's or 4.56's would probally been about right for my use, it could take off at idle without touching the gas in granny low. To try and compensate some I put the tallest 16 inch radials available then 255 16 75's. These trucks still had the older 6 Lug wheels so there wasnt much choice in wheels and tires unless you had custom wheels made which i did on my 1956 F-350 and ran the wide 16.5's on it. I never had a tach in it but the truck stopped pulling at 62 MPH (am sure the Speed O was off some too because of the slightly taller tire size being used over the original size but even still it really could have used an overdrive for those empty Freeway trips to be able to cruse at 65 to 75 MPH. Today I would for sure use a Gear Veders OD unit behind that Np435 to drop the RPM some that or swap in a ZF 5 speed or one of the NP4500 transmissions. Your T18 should work seminar to the NP435, if you could find a T19 though these 4 speeds also gave you a Sincro in the first (granny) gear its about the only one of the truck four speeds that is equipped that way.

Today's ideas.
Additional things to change during a 300 six build for heavy duty use in a 300 long block would be the later 1995 1/2 to 1997 Hypertecic pistons with their metric rings, a set of ARP Rod Bolts along with polishing and shot penning, the Cast crank is plenty strong enough and if you wanted you could have the compleate rotating assembly balanced for extra smoothness at speed. Maybe a full set of ARP bolts or Studs especially if you plan to do a Turbo install. A Clifford or Offy C intake with s 2V Autolite 2100 or Motorcraft 2150 carb would be a good upgrade too. You could also have Shielder Cams custom grind you a cam for about the same cost as an off the shelf cam to better fit your trucks torque needs. I like to keep the over bore on these medium / heavy duty use 300 truck engnes to no more than .030 if possable. Today the later EFI exhaust manifolds are the best stock parts over the old log type exhaust manifolds, but you are already way ahead on your exhaust system already so thats great. Good luck on your 300 build. :nod: (y)
 
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fox81

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Did you check with Ron's auto wrecking in Port Orchard, WA?
No luck with rons. I called horseshoe auto wrecking. They said they have a partial motor in an 85 f150 for $425.. Seems pretty steep. I dunno is that what they are going for these days?
 

pmuller9

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No luck with rons. I called horseshoe auto wrecking. They said they have a partial motor in an 85 f150 for $425.. Seems pretty steep. I dunno is that what they are going for these days?
Prices have gone stupid up and down the coast but I still wouldn't pay $425 for a partial engine.

"sdiesel" who lives north of Portland may be willing to sell one of his spare engines.
Send him a private message.
 

BigBlue94

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No luck with rons. I called horseshoe auto wrecking. They said they have a partial motor in an 85 f150 for $425.. Seems pretty steep. I dunno is that what they are going for these days?
300s are common on the Kansas City area U-Pull style junkyards. Long block engines are $150 to $200, if you pull it yourself. Most of them are EFI engines in F-150s
 

fox81

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Can anyone recommend a carb if i switched over to a clifford manifold?
There is an information overload regarding carbs that work for a mostky stock setup.

if i installed a clifford and put a cam in it down the road sometime, what 4bbl carb would be good? Holley 390 seems to be a popular choice but they are expensive. Ive read people using 600cfm carbs and also small 1bbl carbs. Im looking for a 4bbl carb that can give me the most power while still being reliable and tuner friendly.
 

bubba22349

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Yes a 600 vacuum secondary or 390 or 465 cfm Holley all can work, or a Autolite 4100 or Motorcraft 4150 carb too in my opinion the last two will give you just a little more economy over the Holley and the Holley gives just a bit more power over the others. Good luck
 

pmuller9

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You won't need over a 500 cfm 4 bbl carb.
For a new carburetor,
The Summit 500 cfm carb seems to be working well.
The Edelbrock AVS2 has annular boosters like the former Ford Autolite/Motorcraft 4100s and is very adjustable.
I also like the Quick Fuel Slayer or Hot Rod series carbs.

In all cases it is best to install an air/fuel ratio meter to tune the carburetor as many other here have done.
 

sdiesel

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keep looking for a six.
s&j rebuilders has a good reputation in this area for a stock- ish build. ive not tried them but a number of shops here rely in them for an engine that does not come back.
300 are still cheap and available. best is FB marketplace. i bought an efi ( like i really needed another engine) for 100 .00 it had been on for weeks. there is another for 200.00 but even i know when to draw the line ( when i run out of a. money, or b. space)

i have two virgin 4.00 bore blocks both can be rebuilt with only a hone job.
and i have a fresh .060 over block and parts but need assembly.

there a ton of stuff out there u just need to get into the vein.

keep the 70 if it works. if it gives up on you ( spits shims) upgrade to the metric disc brake thing. i have a locking unit from a 70 i just tripped over this very afternoon.
remember too a bigger wheel in the center housing requires more of the engine to turn.
so a 70 hd is not too bad except for brakes.
your GM axle is superior to everything else.
and the dodge version of the AAM 11.5 has even more strength than the GM version as it has additional webbing on the case. there exists a GM. corporate from the late nineties that is super cool with discs and 10.5 ring. gear . perfect for our sixes. heavily webbed and that third bearing on the pinion shaft.

your going to enjoy this little adventure.
its cheap fun.

not as fun as a mistress but much cheaper.
but more fun than heart palpitations,

pick your poison: boats,bikes,women or cars. the 300 is a good choice..
 

Lazy JW

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It takes power to tow 12K.
You would be working the engine between 3000 and 4000 rpm to make the power you need.
At that rpm range you can make good power and still have longevity with the right parts.
Yup.
5.13 gears will get you in the happy zone :cool:
 

BigBlue94

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Can anyone recommend a carb if i switched over to a clifford manifold?
There is an information overload regarding carbs that work for a mostky stock setup.

if i installed a clifford and put a cam in it down the road sometime, what 4bbl carb would be good? Holley 390 seems to be a popular choice but they are expensive. Ive read people using 600cfm carbs and also small 1bbl carbs. Im looking for a 4bbl carb that can give me the most power while still being reliable and tuner friendly.
I bought my 300 with a clifford intake and headers, and a holley 390. It was plenty of carb, and the engine performed very well. Then a leaking head gasket led to a full rebuild, and I put on a Quickfuel Slayer 450 cfm. Much more tunability than the old holley 390, and it uses holley parts. I estimate im making between 250 and 300 HP and its plenty of carb. I get 12 mpg with a lifted 85 bronco, no overdrive, 37" tires, and 4.56 gears.
 

Lazy JW

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... Ive got an 81 f350 dually cab chasis (from the factory) with a 300 in it. dana 70hd with 4.10 rear end. t18 4speed tranny.

Im wanting to tow my mini excavator and dump trailer weighing around 12k. I know its gonna be slow but has anyone hauled this kinda weight with a 300? ...
Yes. Many times. My White Ox has hauled 20,000 lbs CGVW of hay for many years. At least I got to go out empty, but you will be loaded both ways.

Don't get sucked into believing all of this "Low-speed torque" nonsense you read about the 300; this is actually quite a small engine for heavy trucking, it NEEDS to rev up to make any realistic power. Gear it to run down the highway at 3000+ rpm in top gear at 55 mph regardless of whatever transmission and life will be good.
 

sdiesel

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another point about overdrive. it gets used a lot more than imagined . if for example interstate steady speeds and lightly loaded.
one would assume a mini X is not always on back. it may be the heaviest weight u will see unless you haul your own crushed rock.
many many nights will see you return home sans hoe or trailer.
i use 5th gingerly, but frequently, in for example going south from wells NV to Tonapah through Austin i will use 5th even with a camp trailer.
 

sdiesel

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An axle swap is definately something i want to do as the dana 70hd is kinda an odd ball. Only one option that i could find for a limited slip/posi.

Also im new gearing. But i feel with out even towing that the gearing should be different. Maybe its just the t18. Im set with my new tire size. would that play into choosing different gearing? I think its the stock tire height
235/ 85 / 16 is your choice in tires. like it or not.
nothing else is really practical either from a cost point of view
or from a practical pov.
a good toyo cooper, or such in the above sizes will hold up, ride like a hay wagon , and deliver an astonishing lifespan .
the dually, if this is your first, gets stuck on wet grass, and heavy traction tires are of limited value and are noisy if your rolling 6 of them at highway speed.
my next will be D rated mud n snow with a softer inflate to soften the ride a bit.and with these old fords every little bit helps
 

Lazy JW

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another point about overdrive. it gets used a lot more than imagined . if for example interstate steady speeds and lightly loaded.
one would assume a mini X is not always on back. it may be the heaviest weight u will see unless you haul your own crushed rock.
many many nights will see you return home sans hoe or trailer.
i use 5th gingerly, but frequently, in for example going south from wells NV to Tonapah through Austin i will use 5th even with a camp trailer.
Well, yes, if interstate travel is on the agenda.

I made my recommendation on what the original poster actually stated. My White Ox would be an exceedingly poor choice for interstate travel :)
 

sdiesel

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right.
the manner of travel i refer to is the to- and- from job travel. which would,in his area mean a fair amount of freeway travel

also:
Tony's truck parts in Portland has an inline just pulled from a 68. i cannot say if its 300 or 240.
but just spoke with him on a different matter.
its there , complete oil pan to carb.
500.00
 
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