Howdy guys, I recently recieved a 1973 F250 camper special with a 390 in it. Im looking to do a peformance upgrade (175hp just isn't gonna cut it! like to be in the 300-350 range) just not really sure what is the right path. Like to keep motor, but if a swap is needed please advise.
Thanks guys.

 

No, problem... Research many of the 390 parts from 60-72. There is a wide variety of Carbs., Intakes, Cam, Heads, Pistons, Headers and Ignitions. Several manufature are even putting out new aluminum heads. Almost all 360, 390, 427,428 parts are interchangable and the FE series are great workhorse motors. I'd start with an aluminum 4v. intake and carb, electronic ignition, cam, and headers, besure to use an early (pre 72) timing chain an gear set so the cam is not retarded 4 degrees. Depending on what gears and trans, it will be able to light the tires up.
Btw... torque will make the F250 accelerate, not HP.

 

390 huh? Check the stroke.

How much you get out is going to depend on how deep you go into this motor. What's the budge and are you considering a complete rebuild?

Your motor has several power-killing features. First, as with most FE motors, the exhaust manifolds are very restrictive. A set of quality headers is the answer. A set of cheap headers is the answer for a while...

Next, and especially in this motor, is compression. Ford used 410 pistons in the truck 390 to lower the compression height and compression ratio. This allows the motor to harmlessly flail and thrash at WOT all afternoon on long hills with large loads. Using mid '60s 2bbl "Regular Fuel" or 4bbl model pistons is the fix. Requires rebuild, and you need to check your combustion chamber size etc to determine the CR you will end up with.

The cam. Not sure on the specs, but my guess is it's pretty mild. An RV type cam or similar along with springs that will work past 3500 rpm is the answer.

Intake manifolds and carbs can be stock Ford 2bbl or 4bbl, with about a 650 CFM vacuum secondary 4bbl carb the usual answer.

Of course, there is always more and details details.... But that's the short version.

You might get by just turning the air cleaner lid over and cutting off the mufflers, but that only goes so far....

 

sloth1304 Welcome to FTE. Are you sure your 390 isn't a 360. HP numbers is not where it's at in a truck, it's torque. The FE series engine are torque monsters.

Some of the little 4 bangers brag about 200+ hp but they won't pull the hat off your head. You truck weighs at least 3 times that of one of those cars, and will pull all 3 on a trailer, while getting about 6-7 mpg.

For a heavy truck like yours you don't want it turning much more than 3,000 rpms on the road if you want to keep gas in the tank.




John

 

'73 camper special, I'm willing to bet it's got a 390 in it

If it's running good, throw a 4bbl intake and 600cfm carb on it, and headers. It'll wake WAY up and you'll be very happy with it.

When it comes time to really HAVE to rebuild it, go as far as your wallet can take you

 

Well, since this is not a Chevy, chopping the exhaust and turning the air cleaner lid won't work.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

FE parts are not as cheap and plentiful as small block parts, but they are out there, new and used. <o></o>
You can do headers or if you can find some GT exhaust manifolds and a true dual exhaust you will be fine.
Install a pre 72, timing chain and gear straight up, instead of the retarded gear used to pass emissions.
Finding a 390 GT cam or one of the same specs is not a bad choice, but there are tons of choices since they have been around so long, many manufactures are even retooling for the vintage racing crowd. <o></o>
Intake manifolds are usually kinda pricey, but will shave many pounds off the front end, and give an increase in performance. Be ready to get some help to lift the cast iron intake off the motor, it’s a heavy chunk.<o></o>
For ignition the Dura spark off a 74 and later FE will work, or any other electronic ignition will help in that department.<o></o>
Bumping up compression to somewhere around 9.5 is always recommended for all of the junk smog motors made in the mid 70's and 80's. (not that they were really junk, but just detuned so much to pass emissions) (This is going to require pistons, but they are easy to come by. And a factory type windage tray is also good for a few hp.

Good luck, the 390 has been a great motor for many years.<o></o>
<o></o>

 

I don't know on a 1973, but I had a 1976 Camper Special engine in my 1977 F150. It was a 4bbl engine from the factory. I had to rebuild it as I got it in pieces and the cylinder walls were rusted. I went .030 over and I don't know which pistons the machine shop ordered for me, but it ran great and delivered decent gas mileage empty on the highway. Yes, if it isn't a 4bbl a 600 is great, that's what the 390GT engines used. I had a set of dual exhausts I designed put on it and even with the stock manifolds it worked well. According to Archion, someone now builds a system like I designed for Ford trucks, it runs both pipes down the right side to clear the front tank.

Let it breathe, 4bbl and duals will help immensely. Welcome to FTE!

 

Gotta agree with most of what has already been said. First, make sure it really is a 390 by checking the stroke (wooden dowel thru the plug holes in 1 & 4, with it at TDC will give you a good idea whether it's a 3.50" or 3.78" stroke).
If it has a 2bbl, stepping up to a 600 CFM 4bbl can wake it up, and help the highway MPG a bit, especially when paired with a freer flowing exhaust. Headers help a bit more, but I view them as a personal preference thing. They can be annoying on a street vehicle.
An RV type cam will help a little, but the low-ish comp ratio of 68+ FE's give diminished returns with any given cam.
If rebuilding the engine is planned, bumping the comp ratio into the mid 9's will give great results, even with a stock cam, but even better with a mild-ish aftermarket. There's a lot of options out there, but keep the lift below .500 and duration under 270, and it will even be auto trans/power brakes freindly.
Best of all, a 390 built with this CR and a mild cam, topped with a decent 600 CFM carb, and backed with a free flowing exhaust will typically get the same, or better highway MPG than a totally stock "smog era" (68+) 390, but give way better power, and heaps more torque.
If that's not enough torque for you, look into the 445 stroker kits at survival motorsports. One of those, and you can be in the 500 lb/ft range from 2000-5000 RPM, while still able to run pump gas, and it can appear totally stock on the outside.

 

LOL..... What?????? I added a set of headers too. Come on should be good for at least an extra 100 hp.

 

Buzz, slick looking FE!!!
Not trying to offend!
Back in the day, the definition of Chevy race truck was inverted aircleaner lid, glass pack muffler and a Sun Supertach. LOL... I may be showing my age...

 

What I didn't mention earlier, the Camper Special had a different cam, basically a torque cam for hauling a slide in camper. As for performance, mine would light the tires without a lot of effort with a 3.25 gear running LT235 75R15 tires. If you want specifics on quarter mile times etc. you'll have to ask my son, between that and the '71 Colony Park wagon and his '65 Corsa 140 he apparently had a lot of fun in high school.

 

Welcome.

What kind of budget are we talking here? We need to know that first before we can prioritize parts.
Either way you're going to need pistons. The factory slugs in the 68+ trucks net a very low compression. You simply aren't going to make the power you want with them.
Once you have those then the rest is easy. Just a little better breathing.

Headers provide the best bang for buck power increase. The stock logs (all of them, GT included) are terrible. Without headers all other changes will be minimized because it can't exhale. This means you'll be doing a complete exhaust system. A 3" exhaust will get you the best power, but a 2.5" system should be OK. A flow through non louvered muffler is going to make the most power, but will also be louder than a chambered design. It should be noted that SOME (not sure which as this is secondhand information, but from reliable sources) flowmasters have a considerably negative effect on power via dyno tests.

4bbl intake and a 600-650cfm carb. Independent tests have shown Holleys to make a bit more power, but you know, whatever you're comfortable working on. Many 4bbl intake can get you to that sort of power, so you have a lot of options here.

Then a mild cam, something similar to Comps 268H should be enough.

A post 72 timing set, and a recurved distributor and your set. You can use a Duraspark II off of the 74 and later trucks, MSD, Mallory, etc. The high dollar stuff won't make any more power than the DurII just so you know. Many people myself included run high power (450-650hp) FEs with an MSD box and coil to a DurII dizzy. Works well and saves money.

You're better off doing the work to the current engine than a swap. IMO. The power level your after is easily achieved with what you have. You'll have to do similar upgrades to any stock 351/400/429/460 to make 300-350hp anyways.

 

Sleepy445FE.
Did you really mean "Post 72" timing set??
Have you ever driven a stock 390 GT in a 4000lb vehicle?? The GT mainifolds make a noticable improvement!! Even with standard heads, and the factory 2 1/4" dual exhaust. They may be more difficult to find now, especially compared to new headers, even the vintage Ford muscle parts books noted an extra 20 hp over stock.

 

Ha good catch. No that should be PRE 72 timing set. The 390 GTs gains were do more in part to the GT/CJ cam I think than the manifolds. In Jay Browns book the dyno shows them to be right on par with the 68 log manifolds, maybe a TINY bit better (<5hp). The CJ manifolds are an improvement, but still not even close to headers.