Challenge: build up a 255 ci engine

[MurPHy]

So, does anybody have a photo of a 255 cylinder head? I'd like to see what we're talking about here.

[Marz]

I don't think anybody bothered since you can't build them up like a 302.

Basically it's a waste of money. Hell, if you get lucky and take your time looking you can find a really good deal in a complete 5L. I paid 100 bux for a 1990 5L from oil pan to upper intake. All I did was wait for the right opportunity and jumped at it.

[cb84capri]

does anyone know what the compression ratio of these motors was, and for that matter that of the later thin wall non roller 5.0's as well? i just looked through my 84 capri manual and it doesn't say...

would 289 heads work with this motor for sure? i just found that article i mentioned in my previous post, this is it below:

http://www.mercurycapri.com/showroom...sabapage1.html

cale

[Boss 429]

[quote="cb84capri"]does anyone know what the compression ratio of these motors was, and for that matter that of the later thin wall non roller 5.0's as well? i just looked through my 84 capri manual and it doesn't say...

would 289 heads work with this motor for sure?


The 1980 255 Engines had C.R. of 8.8,the 1981- up engines had 8.2 because of a change in the head com. chamber (more CC's in 1981). Yes the early 289 heads/and 260 ci. heads with the smaller intake valves (I think 1.680 dia.) will clear the small bores,and then any SBF intake manifold will then work. the stock crank is cored for weight savings, (save your dampner,as it must stay with crank),but the NHRA/AHRA stock class 5.0L. drag racers use these cranks,with no problems at near 300 HP levels. remember these engines are 50 oz. of unbalance. not 28oz. Gregg/Ohio

[85T-TopGT]

I had an 81 Cobra way back when. It had the 255. I swaped it out for a 302. Still had that high geared rearend. You could peg the needle (85) in first gear. Had to be running about 40mph in first when I nailed it to get a good start on people when racing. Anyway....I have always had a lot of interest in the little 255 too. As long as a persons goal isn't to match the power of a built 302 I don't think it would be a waste of money. Swap the heads for 289's and have fun with a unique little motor. With a T-5 and some decent gears might be good for a grin or two and get little boost in fuel millage as well. Like I said just be realistic about the horsepower potential from the start and it wouldn't be waste of money. Have fun.

[Clarko]

The 255 and the 200 I-6 have the same bore I just found out.

[samickguy15]

Nothing like bringing up a ghost, but did anybody ever build up a 255???

[zak]

I wonder if the GT40P heads would fit - you would need to borrow a GT40P head and a 255 head gasket and see. Maybe by stepping down the intake valve diameter to 1.78 (new smaller vale seat inserts) it might be workable, maybe coupled with the 86 intake and 14 lb injectors. With fuel prices spiraling upwards, the reduced friction and lighter weight might be useful. The latest 302 aluminum block from FRPP is only 20 lbs lighter than a cast iron block, IIRC.

255/302 *x ~ 300 hp would be over 250. Get some 1.5 inch primary short headers.

About half the internal friction is piston/wall, so figure a 7% fuel economy boost.

How much lighter is the 255 long (or short) block than a 302?

Just some thoughts - zak

[306gt]

I had a complete 255 from carb to pan in the shop. I threw out everything except the crankshaft. The intake ports are more oval shaped then round. I was laughing at it as I took it apart. I new exactly what it was when I first saw it. The cranks are light weight and have a 3.00" stroke just like a 302. They have hollowed out rod journals.

[grtskydog]

I still think it would be cool for someone to try it. Yeah, I know...spending someone else's money. Check this out: http://www.carbdford.com/viewtopic.php?t=8062

According to that, the 289 (non HP) heads have the same size valves as the 255. The 260 heads have even smaller valves. If your goal was to have some fun and make a little more power, I don't see why you couldn't do this.

It reminds me of the discussions on the Ranger sites about "how to make more power with my 2.3" to which everyone responds "just put a V6 in it." I have a 2.3 Ranger and wouldn't mind fooling with it to get a little extra power. It's not always about the 1/4 mi or the dyno, this is just fun tinkering for some.

[outsider]

at the local drags there was a ford pinto with a 255 with 289 heads
dang thing would haul butt.

[grtskydog]

There ya have it! I wonder how much power they were able to get out of it.

[Dean_T]

Something else I didn't see mentioned: Ford also lighten the block for the 255. This is why the 3.68" bore can't be punched out to 4.00" If you think the lifter valley and the main webs of the stock 302 are wimpy (they are), then the 255 is kleenix. Sometimes I wished I'd kept the '81 ex-cop 255, it would have been fun to shoot it with nitrous and see how long it would last before something breaks.

I seem to recall back in my college days a guy I knew had an '81 Capri with the 255 and he went through two of them at least. He drove it fast but I didn't think in an abusive manner.

It's depressing to find out the 255 had more compression than the '78/'79 302.

Dean T

[outsider]

i haven't seen it but my uncles says that pintos gone high 8s low 9s in the 1/8 mile.
i thought it was interesting how he noted that it screamed like a chevy sbc. i guess that would be due to the light crank an probrably lightened rods and pistons.

[grtskydog]

Something else I didn't see mentioned: Ford also lighten the block for the 255. This is why the 3.68" bore can't be punched out to 4.00" If you think the lifter valley and the main webs of the stock 302 are wimpy (they are), then the 255 is kleenix.

Hmmm. Didn't even think about that angle. I guess sometimes Ford gives you a no-win situation...think 7.5" rear, metric wheels, and "central" fuel injection.

[theuglystang]

light rotating assembly
better heads
solid roller cam and valvetrain
VERY good balance job

9000 rpm.....

[cb84capri]

i heard a long time ago somewhere that the 255 cranks were weak. i wouldn't trust it.

cale

[outsider]

the crank has been proven to be a good performance peice. lot of racers are spinning that thing to the moon.

[Mad Max]

never looked into the 255 as performance motor

Does anyone make forged pistons for the 255 or are the cast pistons the only thing that's available?

[Dean_T]

If there are forged pistons, the Ford Six guys should know about it since the 200/250 I6 share the same diameter pistons.

Dean T

[Mad Max]

are they the same piston or do they happen to have the same bore size?

[killrfords]

..................I feel this strange sensation to find one now!?

[Dean_T]

are they the same piston or do they happen to have the same bore size?

I don't know how they differ but I think I've heard of a few Ford Six guys using the 255 pistons for some reason that eludes me right now. If I have time, I should probably to a search on fordsix.com for 255 pistons.

Dean T

[Mad Max]

..................I feel this strange sensation to find one now!?

me too.

I think of it as a challange like tring to get 400hp thru a 7.5 without it blowing up

[mustangpro]

Hey this is cool. There's an 82 V8 Capri in a barn next door. I've been meaning to stop by and check it out, but the 255 has always held me back. Think I'll pay them a visit this weekend.