Would like some recommendations on what to do with my 390.

Background: I bought a 72 F250 camper special last fall with the intention of pulling our camper and horse trailer (approx. 7-8K lbs). I currently pull our camper with a tow package equipped Expedition (5.4L, 373 gears). It pull it ok but i wouldn't want to pull with anything less. So, I'm wanting this 390 to at least match the power/torque of the 5.4. So, i'm going to need roughly min 120 HP + torque gain.

Current state: Im working on getting the 72 on the road (rockers and exhaust are bad). So, I'm going to have to address the manifold vs header issue quicker than what i was expecting to.

Recommendations: So, i was wondering if anyone had any recommendations for me as to what to do with this 390. My main goal is to get as much early RMP torque as I can get using the stock heads (for now). First phase was starting with installing a RV cam, aluminum intake, 4bbl carb, recurved distributor. I though of replacing the heads maybe next year if it warranted.

So, is my thinking on track for what I want out of this 390 and if i'm keeping the heads stock and not going for overly aggressive HP gains, are headers warranted at this point? Would I see much gain for the $800 i'll be putting out?

Just to be transparent, I've added power steering to the truck and starting on the drum to disk front brake conversion. This truck also has a 373 rear end

Thanks in advance

 

Headers are always a good idea for the FE.

Shorty Sanderson headers will eliminate the stock bottleneck and give you the least trouble fitment wise.

With 7 to 8,000 lbs, I think you could use the dished car piston with the 1.77" (approx) compression height. This was said to be good for 9.5 in the regular fuel 390s in '66 through '70.

Pickup 390s used the 410 piston, with approx. 1.66" compression height and had low 8s for compression with a sunken piston.

Ford and everyone else used low compression for pickup motors--even lower for medium duty trucks--to avoid meltdowns at sustained WOT loads.

One thing on the heads is to make sure the hardened seats are still there as that's important for durability especially with a load.

RV cam, Performer manifold, 600-650 CFM carb, recurved distributor--all good ideas.

There are numerous 390 builds in the FE forum along with folks who can give you particulars on each part.

One high dollar item would be a roller cam. That reduces greatly the chance of quick wear/outright failure of flat tappet cams due to oil and metalurgy problems.

 

Your application is why Ford started putting optional power disc brakes on F 250's in '68 and optional 460's in pickups in '74. IMO, look for a complete good running lower mileage 460 with the automatic (fan to driveshaft) out of a mid 70's Super Camper Special (not getting any easier I know). Grab the larger 460 radiator as well.

 

Well. Funny you should recommend that. I have another 79 I'm building and it has a 460 with a c6. I had thought about taking it out and putting it in this truck

 

what transmission do you have? i wouldn't want to do this with a C6... not that a C6 couldn't handle it from a durability stand, but because its going to rob a ton more power than the 4r70, 4r75, or 4r100 you had in your expedition. 3 gears without any lock up and no overdrive so you'll get even worse gas mileage that you do unloaded. not knowing what you have behind the 390 and honestly regardless what's there, i'd probably swap in a nv4500. you'd have a good strong transmission with overdrive and none of the loss from old automatics (if you have an auto)

headers and heads increase HP at higher RPMS and in many cases it robs low RPM power which is what i think of wanting more when towing.

if i were going to swap in a 460, i'd want one with a zf5 or a 4r100 with the only downside being you need a computer for the 4r100.

not saying you can't do this, but i have my doubts your 72 will be a better towing experience than the expo unless you did a diesel swap other than having a cool old truck to do it with.

 

Truck is an automatic.. c6 transmission

 

Trans is equally important as stated above. An appropriately built 390 (or any motor) and a c6 won't match the modern ex.

What you want to have is quite expensive, aka resto mod.

What is your budget? That will determine your path here. Cheapest way would be to replace the whole drivetrain with something from junk yard.

What shape in the 390 in now? bolting parts on the outside will only get you so far. Can bolt up a modern 6 auto (6R80) with an adapter. ($5k)

I suggest a 7.3L gas godzilla and 6R140 takeout combo ($10K)

 

a modern torque monster with an adequate 6,8, or 10 speed would be amazing, but it would also be the most expensive option like smokey says.

a manual behind the 390 will make that feel so much more powerful even though its only decreasing power loss. i wouldn't be surprised if a c6 results in more than a 30% loss to the wheels so maybe with a good manual you are only losing 15-20%? idk. the 460 would have more power and torque and you have better trans options with overdrive, but regardless, if you wanted to put money into any motor to make it better at towing i wouldn't be overly focused on opening up the intake and exhaust as both upgrades tend to push your power curve up in the rpms. i'd look at stroking it. any increase in stroke increases torque (which is obvious if you think about it... if your crank is a bolt and your current stroke is a ratchet, stroking it is like putting a cheater bar on the end of your ratchet. the biggest issues with increasing stroke is increasing the possibility of piston slap and cost. increasing piston slap isn't likely a concern in a tow vehicle because you aren't going to be turning 5-6k+ rpm where its most likely to be a problem and cost isn't too much more than what you have in your current planned mods.

if i were going to the trouble of pulling the 390 to put a stroker kit in it and i already had a 460 sitting around, i'd be putting that stroker money into a good trans for the 460 and dropping that in. if i had a little more money i'd be looking at 12v or 24v cummins swapping it with a nv4500 or nv5600. or if i wanted to keep it ford a 7.3 idi from a 94 so it's already turbo'd anything more modern than that would be awesome, but more complex and quite a bit more money. a 7.3 powerstroke would be awesome but those people think they have gold and price them accordingly. a bullet proof'd 6.0 would be an easy fit, but you're 5k in just bullet proofing it correctly and you have tons of electronics. i think a coyote swap would give you the power you want, but i doubt you can do that for anything less than 10k and that would likely be hard to do at that and the godzillia would be even worse.

with all that said, i'd follow whatever you plan to do... its also your truck and your money so do what you want to do. i have a 75 f250 with a 390 and a c6. there are 3 trucks i've owned that tow worse. a an 86 bronco with 302, 91 4.0 ranger, and a 99 jeep cherokee 4.0... my 06 5.4l f150, 08 4.6l f150, 14 5.0 f150, and my 19 d.7l f250 all towed exceptionally better with atleast twice the mpg's

 

Having towed our 10k lb fifth wheel over several states with my '65 F250 with a stock 390 and now a stroked FE, I'll give my ideas for dream setup and let the OP dial back the cost as needed...

- Tranny: If staying automatic I'd get a Ford 6R80. There are adaptors and control modules available. If switching to manual, I'd look at Tremec TR4050. Behind my FE I have an NP435 with a Gear Vendor overdrive. I like it a lot, but if starting from scratch I'd go with a Tremec TR4050.

- Rear: I'd switch to a 4.10
- Distributor: Recurved was mentioned but I'd get one with a lot of adjustment room and dial it in to my preferences for what ever customized engine I was having built. Timing curve (imo) is about engine parameters and personal preference.

- Engine: Stroke it to 4.25 inches. Find an engine builder experienced in FE's and get a roller cam. Do not waste time and money buying a cam off the rack or based on recommendations from folks not experienced with FE's. Besides avoiding possible cam wear, a roller cam allows use of modern oils which I believe give better fuel economy based on results with my '65. Get a modern piston ring pack for better sealing and less friction. If staying with 390 cubes, a performer 390 will improve torque and power for towing and may still be better than a performer rpm even if stroking for more cubes. The performer 390 will outperform the performer rpm in the lower cubes and at lower rpms.

- Fuel economy: I can't speak for mpg with automatics behind FE's but towing 10k lbs with a manual on the freeway I got 8 mpg with the 390 and a little over 7 mpg with the stroker FE...in other words, competitive with a 3.5 ecoboost when pulling 10k lbs.

Again, this is the dream setup and very pricey. It will hang with and many cases out pull everything in factory pickups up to around 2010. The current godzilla and especially the scorpion platforms, on the other hand, with 10 speeds are plumb over the top.

 

the tremec 4050 is like the nicest shifting truck manual transmission you can get. if you want to go manual and you can make it work with your budget you should. if you need to go cheaper, people have successfully mated a nv4500 to an FE and the zf5 came stock behind a 460.

with the autos i've never seen anyone make any decent trans with a locking torque converter work behind a FE. that's not to say it hasn't happened, just that i've never seen it. i'm sure 65ford is right about a 6r80 and the newer 10 speeds, but you can bolt up a 4r70, 4r75, or a 4r100 to the 460 you have without the need of any adaptors.

to compare 65ford's mileage behind his 390 and mine with a c6 and 3.73's, i get 9 mpg unloaded and 5-6 towing a ~7k camper obviously the C6 is robbing a ton of efficiency

 

A 4R70/75/4R100's are Mod motor transmissions so you must have an adapter. Unless you have a 5.0 Explorer or a diesel with an 4R100. The E4OD was used behind 460's till 1998 F-250/350's.

 

sorry you're obviously right richs2659... we were talking about an expedition earlier and must have been stuck in my memory.