One of the downsides of being a fan of cars made between 1972-1995 is that more often than not, one look in the engine bay is all that is needed to remind myself why these cars are so derided. Even in the best forms they both aren’t a match for late-model stuff and are mere shadows of what they were prior to. Government regulations, EPA panic and a weird taboo on performance made for some lackluster and frankly forgettable vehicles. Nowadays, reverse engineering can do wonders for these castaways. We know that familiar platforms had a lot of the old setups and that tuning tricks worked the same regardless of the era, but what a lot of people have tended to do is trash the running gear in favor of the quick answer. I’m just as bad, but there have been times that I wonder if that is such a good idea. It might not be cost effective, but there’s a certain something about building up the stock mill to maximize the potential it could have, provided you are realistic about the goals.
And as luck would have it, I have the perfect start for this mini-series: the Ford 4.2L V8. A 255ci smog lump if there ever was one, the 4.2 suffered from a combination of poor heads, a strange bespoke intake/head port shape and one of the sorriest V8 power ratings to ever befall Ford’s proud Mustang. I already hear the cries of “just find a 5.0!” in the distance, but there are a few things that intrigue me about it: it’s based upon the Windsor architecture, so there’s hope for modifications. The small bore and stroke could actually mean some entertainment, in a similar vein to a 289, so if you coupled either 260 or 289 heads onto the 255, that would also allow a wider array of intake options. Add a roller cam, a decent balance job with the rotating parts, and would 300hp/300tq be out of the question? I’m a driver, not a mechanic or engineer…you tell me!
They had tunnel port heads, didn’t they? I have to wonder if there’s enough meat in those for a gonzo port job. If I hit the water jackets, I could always swap on more conventional heads. Then fab up a cross ram intake with a set of independent throttle bodies, put a really wicked cam in it, and have a rev it to the moon screamer.
Small displacement doesn’t have to be a bad thing.
Were it my project, I’d have the heads shaved, chambers ported and polished and larger valves put in to allow better breathing. Find a nice intake that flows well and fits a decent enough carbureter. Complete the package with good rocker arms and springs and an angry cam. On the bottom end, go for lighter conrods and pistons to help it spin freely.
If the cards are played right, such a build could make an engine that loves to rev high. Combine that with nice gearing, and it should be a fun car.
The problem with the 255 is the only head that fits is the stock head. All the current heads have wider valve spacing so the valves with hit the cylinder walls.
Flat plane crank with a lightweight rotating assembly, sky high compression and run it on E85.
I don’t know enough about Ford heads but I’d think some small chamber, small valve Cleveland type heads would be pretty good for RPM flow NA.
Just because you can doesnt mean you should…..
Seems the heads are the weak link…figure that out and you could be on your way to making a little power…but probably still less power and torque than a V6 from an Edge or a S197………
This…At least the first part.
You really don’t want to waste any money on a 255. The bores are so small that no other Windsor heads will work, so the 255 heads had to have tiny valves to fit the bore. No other manifold will fit the heads, and there aren’t any aftermarket manifolds at all. There’s just no reason at all to mess with it.
This seems like one of those cases were to make it run, you could get imilar power and a better curve from a 302 or a 5.3L or such
Airflow, Compression, and Camshaft, in that order. In order to increase the airflow, you need more displacement, so you need to toss out the 255 and build a 347!
In all seriousness 300 horse is way out there for that engine. Yes it is based on Windsor architecture but the bores are only 3.680″. 289, 302, and 351 heads are all based on a 4″ bore. As stated above, putting better heads on would not work because the valves would hit the bore. The engine is a thin wall casting so you can’t really bore it out more than .030”.
Porting the stock heads along with putting slightly larger valves in, milling the heads and putting in a cam would help with output but 300 horse is a long stretch for those tiny heads. My best guess would be 180-190 horse, if you have a streetable cam in there.
Going that deep into a 255 would be a waste of time and money for the horsepower gained. For a street car, where you don’t have to adhere to a displacement limit, bigger is better.
I believe the most cost effective thing you could do for that car, is go down to the Pick n Pull, and get a 5.0 from an Explorer for $300. Put a 4 barrel intake and carb along with your Duraspark distributor (be sure to make the ignition curve correct and change the drive gear for your new combo) on top, get the FRPP headers for fox bodies that fit the GTP heads and go have some fun. For about $7-800 total you can have a car that runs good and can actually get out of its own way. Then if you want to later, upgrade the cam, do the larger valves and such, it would actually be worth it.
If you want 300 horse from that 255, nitrous might get you there, but you better have the fuel and ignition spot on.
In the end, it’s your car, time and money, do what you wish with it. I just think you’ll have more frustration than fun with the 255. The 5.0 from the Explorer will drop right in, everything but the fuel pump bolts right on, and if you tune it well, most likely have better fuel mileage than that old 255.
Just my .29¢
EPA EPA -isn\’t that what Grandad Simpson was bellowing in the Simpsons movie?
I\’m sorry, but I found all the rest of the comments sent me to…… zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
They sell horsepower additive in 10 lb. bottles and they sell oil-dri in 20lb tubs.
I vote you blow it up and replace it with a 2.3 turbocoupe engine.
the 255 is a debored 302, therefore I would add a 1/4 inch stroke, use 289 heads with slightly smaller valves for cylinder clearance , up the compression to say 10.5:1 and of course add larger hydraulic cam, high rise 289 intake manifold, holley 650 cfm carb, headers-1-5/8 ” dia.
if you have to keep the 255 call On3! and get a turbo. Other wise the P motor is a good choice for cheap jy push rod power. Better yet the cost of the new 5.0 cammer from the f150 is coming down get one of those.
Some of you guys seem to have that 255 confused with Fords old Indy pushrod motor. The 1980 style 255 is best put on the tailgate of a pickup that is back up rapidly to a river or scrap pile. The heads are hardly Tunnel ports, the ports are so small you could run those 3/4″ diameter ProMod pushrods without offset rockers.
NO NO NO NO NO NO NO NO NO
I had a 255 in a Ranger once. EFI’d even. Swapped an E6 headed 302 in it’s place and it felt like I strapped a JATO booster to the roof.
DO NOT WASTE YOUR TIME AND MONEY IT’S NOT WORTH IT.
We built a 258 cu. in. small block Chrysler, same bore and stroke as 255 ford, put it in a 72 dodge crew cab. It ran a 15.16 et at 92 mph in the 1/4, and ran 121 at Bonneville, with a cam grind from a 271 hp 289. with a bigger cam it ran 126 at Bonneville. You make the call. As Smoky said No one told me it couldn’t be done.
The only effective answer to the one off restrictive heads is a power adder. So, steel crank, hbeam rods, forged Pistons. Polish the combustion chambers and place stainless valves. Roller cam with medium lift ( .490 ) no more than 275 duration and add twin turbos . Problem solved!
The 260-early 289 factory heads with the small valve package WILL fit the 255 3.680″ bores… With a decent port job and a good induction system, Roller cam,etc.. !3. to 1 compression, custom Diamond pistons, I belive i could see 300 hp… on the engine Dyno. Im a well known engine builer here, I see no problems doing a build up. I even have a spare 255 or two.