Can the 300 EFI cylinder heads work all right using a carburetor intake manifold & carburetor.

Understand the carburetor heads are 76cc, while the EFI heads are 65.9cc, stock, but the EFI head incorporates a feature in the dome that creates a swirl to the intake air charge.

 

Ford has been making the 'swirl' or fast burn chamber for longer than the efi model has been around. I have one that was made in '82.

 

The later EFI head can be substituted for the carbureted head. The compression ratio will increase by ~1/2 point.

Some use the 240 head to accomplish the same thing.

 

An EFI head can be used on a carb engine but why? Swirl is nice but not at the expense of flow. A 240 head has the same chamber size and can be ported to flow almost double an EFI head. That will more than make up for any gains from swirl.

 

Recently performed some calculations using after market "Seal Power', D dish shaped pistons
using Mr Gasket and Edlebrock head gasket.

Mr Gasket, 4.22" OD x .02" compressed thickness
300 carb head, zero decking, CR = 8.5
300 EFI head, zero decking, CR = 9.2
difference: 0.7
240, zero decking, CR = 9.1

Edlebrock, 4.1" OD x .047" compressed thickness
300 carb head, zero decking, CR = 8.1
300 EFI head, zero decking, CR = 8.8
difference: 0.7
240 ,zero decking, CR = 8.6

The Edlebrock gasket will take up more warp then the Mr gasket.

Are the exhaust and intake ports identical between the EFI head and carb head or is the carb ports larger or smaller flow area.

EFI cylinder head has the "heart" shaped dome that introduces swirl,
while the carb cylinder head has a "D" shaped dome.

What is the advantage of using the EFI cylinder head?
There must have been a reason for the design change.

Is the 240 head "D" shaped.
Appears this engine was manufactured from 65-76.

EFI head uses bolt down rocker arms, while carb head uses studs.
Do the studs loosen up?

 

The 240 has a kidney bean shaped chamber. If you are raising the cr then I would use the Felpro gasket, the hp one that costs about $48.99 on Summit. I would also think long and hard about your head bolts that have held torque for how many years.

There is a site that sells the head bolts new, as well as some other great and hard to find items when rebuilding these engine, like the cam thrust plate, the dowels for the head, and the keys for the crank shaft timing gear, etc. Iirc the site is head bolts dot com.

 

It's not the shape of the chamber on the EFI heads that makes the swirl, it is the cast-in restrictions around the valves that limit and direct flow to create that swirl effect. Leave the EFI heads for engines with EFI.

The 300 head is so undervalved and breathes so poorly your first thought should be "more air flow". Go look at a head off a 351M/400. Check out the size of the ports and valves next to a 300. Like a garden hose next to a drinking straw. Or me next to Peter North. The 400 has the same size cylinders and plods along at the same RPM range as the 300.

Perhaps if you search Frenchtown Flyer's posts at FSP you can find a technical explanation for why Ford made the change. Part of it is probably due to differences in how carbureted and fuel injected engines flow and mix fuel/air. The fast burn is a lot more manageable with electronically controlled timing and a knock sensor as well.

Are you planning an engine build? If so, what vehicle is the engine going to power and how do you plan to use it?

Smaller chambers have some advantages but if you're building an engine for a truck you may be better off keeping the 300 head and finding some pistons that will put the compression where you want it at whatever deck height.

The engine I've got at the machine shop right now is an example. I ported a 240 head that I'm using and once all is said and done the CR will be ~9.7:1. Higher than I'd prefer but not tragic since the Bronco is a toy, has a 5-speed, and mostly won't be used to tow. Running premium gas is acceptable. What's $20 a tank when you're hauling ****? With a 300 head and 9.1:1 compression it might run on regular. Something to think about.

 

Baron, you never asked Raven about his application. If he is building a mild street motor, to run on regular gas and get good fuel efficiency, the efi swirl head will be what he needs, certainly better than the 300 smog head, and should be fine with a carburetor. That's what Flyer told me when I asked about the efi head.

 

The truck will used as a farm truck. It is a 1973 F250 with most of the original brown paint worn off from weather with FE390, C6, 4:10 rear, rated at 8100# GVWR.
The 390 only runs on 6 cyclinders, since two cylinders only have ~ 30 psig pressure from static test. Don't want to put a nickel in this engine.
Like the 300 because it develops about the same torque as my 351W/C6/Holley 4 bbl/3.55 rear that was in my 1985 Bronco that I owned from 1987 to 2012 and put about 450K miles on it.

Purpose of the truck will be to haul 1000 gallons of water in a portable steel tank mounted on a dually single axle truck frame about 8 miles round trip to and from the watering hole.
on flat ground, mainly on hard dirt road.

Another purpose is to haul a 2500 lb Ford tractor to the tractor show once a year, 200 mile round trip. The tractor will mounted on a wood flat bed with the box removed.
The loaded truck must go up an 8% grade from Grapevine,CA (sea level) to Gorman,CA (4500 ft elevation. better known by the locals as the grapevine. Trucks even on the east coast even know about the Grapevine.
Have to go down the hill ,also, to the tractor show.

On the Felpro head gasket thing, FEL-1024 HP, the compressed volume = 8.77cc, while the compressed volume on the ,Mr Gasket 1132G, compressed volume = 4.57cc.
However, the Felpro gasket is more foregiving on a warped head and not so flat block deck. If the head is surfaced and the block decked the Mr Gasket should seal, OK.

The truck will also haul new sappling trees from the Nursey to the Orchard for planting once a year. And may some concrete blocks to build another green house and maybe more fence posts, etc.

Seems like the 300 EFI head would work on the 1980 short block. Has the same push rods but would need new rocker arms since the EFI cylinder head has bolt down rocker arms. The EFI runs right on the edge of detonation with CPU controls to maximize power output.

Don"t know if the EFI head would work with carburetor application.
Want to keep the engine simple as possible.
Currently building an engine test stand.. will most probably end up testing both EFI & carburetor cylinder heads before installing engine into truck.

Can always back off on the timing with a bad batch of gasoline with carburetor engine. Had a two piston melt down on my Bronco going through Cedar City ,Utah at high altitude.

Got 1/2-20 x 1/2" set srews to plug up the air injection holes in the cylinder head.

 

No reason the efi head won't work fine for carburetion, actually should be particularly good with carburetion. A single carb on a long straight-six manifold has a challenge in getting a homogenous air/fuel mixture to every cylinder, and a head that imparts swirl addresses exactly that problem. Go for it. It's what I'm doing for a 300 that's going in my work truck. I want a carb for that, even though it's less efficient than efi, because it's SIMPLE, has no electronics, fails gradually rather than instantly, and is fixable in a parking lot or whereever. A business vehicle has to be absolutely dependable. The Dura-Spark ignition is electronic, but I carry an extra module and pickup.

I picked up an Offy Dual-Port intake manifold cheap ($75 with a Holley carb) from an FSP member, to try out on this work truck. The Dual-Port is not a performance manifold, but with a small 390cfm Holley spreadbore it theoretically should give a little more bottom-end and mid-range throttle response and fuel efficiency than the old Ford manifold and 1bbl carb, just what I want in a truck. The swirl and the higher compression of the efi head, plus a set of efi exhaust manifolds flowing into an upgraded exhaust system should help even more. if you improve gas mileage on a one-ton truck from 9mpg to 11mpg, that's over a 20% improvement. The added power will be welcome, too, for this old tub.

 

An advantage of the EFI head is that it requires much less spark advance for optimum performance. So if you are not using the computer to control timing and are planning on using a DS distributor then you will have to retard the timing - something on the order of 10 degrees - and experiment to get the best spark map.

I think it can be made to work well for your application, with some experimentation.

 

Just a little minor correction but I'm pretty sure the 240 was only built until 1974. Unless they offered them as an industrial engine after that. As far as I know they were available in fullsize cars from 65-72 & Full size trucks from 65-74.


And here's my take on the EFI head. If it's all you have and need to get the engine going, use it. But they are prone to cracking and have severely shrouded intake valves. So any benefit they give you is eliminated by the restriction of the flow in an unready restrictive head. And less dependability then the carbed heads.

My opinion is likes BaronVonAutomatc is. If you are completely rebuilding a 300 then stick with the carbed head. If you want to raise the compression go with a set of pistons that will get you the compression ratio you are after.

If you aren't doing a full rebuild but want a slight compression bump the 240 head is a better choice. It's going to flow better then the efi head and be less likely to crack.

 

The 1980 300 is currently supported on three concrete blocks outside in the dirt.
Plugged the air injection ports, yesterday, with 1/2-20 x 1/2" set screws with Permatex high temperature thread sealer.

Checked the cranking compression with stock heads with plugs removed.

Results: 165,165, 175,175,165,180 psig

Sort of happy with these results.

Going to calibrate the pressure gauge because these numbers seems too high.

Did an intake valve study using the "Autozone" parts data base
Intake valve diameter from 1965-1972 = 1.779"
1973-1976 = 1.752"
1977-1984 = 1.779
1985-1993 NOT available
1994-1996 = 1.783"

Must be something up with the 85-93 cylinder head?
Data base for 3.9L (240) shows same intake valves as 4.9L(300) between 1965-1975, 1975 showing the last year for the 240.

What is up with the 73-76 cyclinder head?

If choosing a 240 cylinder head to bolt to 300, would choose 65-72, only... NOT 73-75 with smaller valve diameter.

 

[QUOTE=seattle smitty;14056253]"...a small 390cfm Holley spreadbore...."

That one didn't make it past the editor. I could of sworn the 390 is a square bore.

 

And surely you know more about it than I, because I haven't picked up the carb yet, and have never owned one of those. I just had the idea that it was a spreadbore (smaller primaries than secondaries). My bad, good catch, and thanks! Still, that 390 seems to get the biggest show of hands as the carb that goes well with an Offy Dual-Port to be used on a heavy truck motor. Or am I wrong about that?

Fordman, there seems to be disagreement on whether the efi head cracks any more often than the others. If I recall correctly (and since he has shown up here he can say yea or nay), Flyer, who was or still is a FoMoCo engineer, said he thinks there's about the same amount of iron in an EFI head as the others (if somebody has one of each, he could just weigh them). Did I get that right, Flyer? Meanwhile, Fordman, I'm trying to remember if you are the FSP member who is a full-time auto mechanic and has himself "seen it all;" certainly that would give you great cred. In any case, WHY do EFI heads crack, and can anything be done to keep them from cracking? I want to know, because I've got a couple of people watching for an EFI head for me.