yeah i remember starting cars with carbs in the winter.they didn't start anywhere near as good as fuel injection.no contest there.carbs were not improperly tuned either.it was easy to flood them too if you pumped too much.you'd could end up with flat batteries due to cranking too little without using enough fuel or flooding it by going too far.you really had to know your car and hope and pray you didn't face parking into the wind lmao.yeah nope.efi took us to great places as far as this goes.

yeah it's purely nostalgia.

it's not a DD.just a toy.more power than i know what to do with,regardless of it drawing in fresh cooler air or not.id never notice a difference.

 

Of course, I can't specify where Lead Head found his info, but he may not be far off. The Wikipedia entry puts the horsepower anywhere from 114 hp net in 1978 to 170 hp gross in 1965. The EFI engine introduced in 1987 was rated at 145 hp net.

https://en.wikipedia.org/wiki/Ford_s...rth_generation

Well, I agree! Seems like we can have something in common.

I'm going to qualify my support on this one.

First of all, I would be a lot more inclined to agree if we were talking about anything but a 300 six.

In my opinion, the strength of the 300 six is in the long stroke which gives it a lot of torque potential. The weakness is in the head design, which flows poorly. Coupled with relatively few choices in camshaft profile, it becomes quite difficult to see performance gains simply through the induction system.

Simply swapping EFI for carb is not likely to make 30 hp difference one way or the other, but the last carbureted 300 six made 122 hp and had that dreadful feedback carburetor system. The EFI 4.9l made 145 hp. There was more to this engine than the EFI. There was a redesigned exhaust manifold with much better flow. I don't know what the flow numbers would be on the EFI system, but I expect they would likely be much better than the carb and manifold that preceded. Swapping backwards to a more restrictive intake will reduce horsepower, even with the better EFI design exhaust manifold.

I have owned 3 of those 300 6 cylinder engines in the past. All had their unique characteristics and story. First one was a swap into an 80's E150 van replacing a 351W. That van pulled just as hard as the Windsor, but top speed was restricted. 75 mph was pretty optimistic, even without a load. Next one was a 4.9 with EFI in a 92 Bronco. Probably the best running engine of the lot, but performance was far short of spectacular. Gas mileage in particular was pretty disappointing. Still, that truck could pull anything. Last is a 67 F350 that I currently own. Simple and basic. I rebuilt the original carb, but I have never been able to get it to run quite right. I have been informed by our local carb guru that the power valve in the rebuild kits is of inferior quality and likely responsible for the inability to tune this carb properly. But it does run and I use the truck for dump runs. Always starts, but I often have to run with the manual choke pulled out slightly.

 

The 4.9/ 300 received a lot of other changes to the engine itself that accounted for some of those gains. The exhaust manifold design was much better, the cam was better, and the compression was better on these years compared to the older carbureted versions. So, it wasn't just because of EFI that the 300 gained power. If you take a later 300 engine that had EFI, and swapped to a carefully selected carburetor and intake, you *should* have roughly the same amount of power.

For example, go and look at those same power ratings and you will see the 1984 -1987 F150 with the 351 and 4-barrel carburetor made the same amount of power as the 1988 - 1993 version that had EFI.

NOW we are getting back on track. I agree with you here in that it is not cost effective to swap from EFI to a carburetor. But you didn't say that earlier; you just told the original poster he would "lose power." Leaving out that variable changes the meaning entirely.

"5 hours to tune a choke?" Seriously? It took you 5 HOURS to loosen the 3 screws enough to rotate the choke cap? Don't be ridiculous. A carbureted system will need a choke adjustment to start well from extremes of -20*F to 100* F. And that is where EFI clearly has an advantage. But all we are talking about here is a 2-minute choke adjustment with a screwdriver, certainly not 5 hours that results in 10 - 30 pumps to make the engine start.

"10 - 30 pumps" to start is ridiculous too, and SEVERELY misleading. If you were experiencing those kinds of troubles, something else wasn't right. Unless, of course, your vehicle was allowed to sit for weeks. If so, that is a fault of the design of the fuel pump, not the carburetor. As you know, an EFI vehicle will have an *electric* fuel pump. If you replace the mechanical fuel pump that is found on a carbureted system with an electric fuel pump, that problem will be eliminated.

I agree with everything here except the very last part about not having the same all-around driveability. All other things being equal, there isn't much difference between a properly functioning EFI system and a well-tuned carbureted system.

 

The 4.9 camshaft was the same for all years carb or efi.

I grew up when there was no efi, our cars started fine regardless of weather, and didn't suffer from reliability issues, matter of fact, they ran for nearly a couple decades, completely untouched, and the fuel economy wasn't that bad. Most problems with carb engines, lead back to the engine being modified, by someone clueless with big ideas. Don't recall a huge sigh of relief when efi arrived.
Switching an efi Ford 300 to a stock carb setup, makes no sense. You will lose power.
But if you want to add the aftermarket intake, carb, headers and a better cam, even something small like a 260, then there's no comparison to a stock efi. There's factors, other than tuning software, that make a modified efi 4.9 less desirable. Major being no intake options, and there's a great chance your efi head is cracked, and you don't even know it. There is or was a cast iron aftermarket option, that addressed the cracking issue but otherwise, it was a stock port/combustion chamber head.
The reasons why I like, maybe even prefer efi, have absolutely nothing to do with power potential or economy of, as with fore thought, both can be made to perform.

 

I do know someone who did a 300fi swap to a carb but it was because the 300 in his 78 f150 blew up and he didn't want to swap the wiring and fuel system into his beater truck. That was understandable, that being said, he had pinging problems all the time unless he ran 89 or higher octane. I'm guessing its because of the higher compression of the later FI engine that now didn't have the proper fuel distribution with the long runner carb manifold. It ended up fragging the number 6 piston in the end, then he dropped in another junkyard old carb 300 and had no problems. Will that always be the case? I don't know but that is experience I know of. And no I don't hate on carbs, I have a quadrajet on my hot rod lol. You get more flack for that then doing an EFI swap haha.

 

Interesting thread.

I'd run FI on my weedwhacker if I could.

That being said...

Which a certain old car mag I read once called "essentially mechanical fuel injection". Kudos & reps to you on the courage/skill to use it.

 

Less courage and more "nobody thinks they're any good...that's what I'll use" mentality. I'm an advocate of trying to help when I can. But also know through personal experience that the human brain learns better from finding out for yourself what doesn't work, faster than learning what does work.
I was the 11 year old that got caught drilling jets in the lawn mower to get it to run right on isopropyl alcohol, when dad couldn't figure out why it would flood on gasoline.
If the guy wants to convert to carb let him, he may be skilled enough to make it run good. But, odds are he will run into problems and he will have to work those out to its a learning curve. Or he will just drive it around with the problems till he is tired of it and get rid of the truck.

 

I don't get the ideas that carbed vehicles are harder to start in the cold. I lived in northern Alberta in the 80's and never had an issue with many different cars and trucks i owned at various times. Most vehicles were one or two pumps of the pedal, my chevy trucks used to be three or four lol.

I can see a sequential port fuel injection on a same engine boosting hp, there is no way the old fuel injection boosted 30hp with nothing else.

All that said there is no reason to switch a newer truck over to a carb other than for simplicity.

 

Regarding cold starts, I agree with Lariat and with the people that say a carbed engine is harder to cold (and hot) start. Yes, a properly set-up carb starts well under all conditions. But I've never driven one. Even back in the late '70s and '80s when I was driving brand new carbed vehicles there was always some condition it didn't like. With my dad's '79 Suburban it was cold. You had to pump it the right number of times. Too few and it didn't start. Too many and it flooded. With my '85 F-250 it was hot starts. The only way it would start after a hot soak was to pump it a couple times (which flooded it), and then hold the pedal to the floor to clear the flood.

And to say nothing about elevation changes. Living in Minnesota that wasn't an issue. Until we'd go to Colorado skiing or hiking. A flatland carb does NOT like to run (let alone start) at 12,000'.

And then there's the inevitable situation (in Minnesota, at least) of the heat stoves rusting out so you don't get the heat you're supposed to get after cold starts as the engine warms up.

Are all of these conditions unsolveable with a carb? Of course not. If a carb is set up correctly you can avoid all of that (although you do need to rejet when you change elevation that much). But they are almost never an issue with a factory EFI.

I will grant that a carb has a better "limp" mode. When an EFI system has problems they tend to be major driveability issues (or won't run at all) while a carb will slowly get worse without stranding you unexpectedly. But, on average, driveability is MUCH better with a factory EFI than it is with a carb.

 

OK, I get it.... stick with EFI. To me Carbs are familiar and easy, BUT I do like a challenge and would like to keep it as original as possible. That said, OK I have replaced all the vaccum lines, new relays I have pulled the tan/green line (EEC ground) and tracked it all the way no breaks...When I apply power I get power on all lines going into the EEC & FPRelays, I also get power into the Inertia switch but nothing to the pumps. I have constant 12v on the EEC ground, It should only be about 3 seconds when the switch is turned on, right? I am going to go back and check all my grounds, then the inertia switch. Then tes the Pumps by jumping them directly. It is frustrating because I bought a new computer and its the same issue. The truck will turn over strong, just no gas. I have time.... I had just hoped to have it running this summer. On a good note, I have been getting parts from a salvage yard and have restored the entire interior. I have evn found the Wood grain trim with no damage, and there are at least one or two more sets in the that salvage yard. If anyone is around western MD and has a free day to play with wiring feel free to stop by!

 

Something I'd like to add, not directed at anyone, is that you can take the number of people that say they can tune a carb and cut that at least in half.

The number of adjustments on a carb is probably greater than the number of people you know that can use them effectively. It's more than just choke, idle mix and idle speed. Getting g the optimal fuel curve from your choice of carb can be a chore.

 

just put a new 750 on my '68 429.

 

If I couldn't get a Quickfuel, I'd get a Holley. But I can get a Quickfuel so...

 

I am checking all my wiring Harnesses... Can anyone tell me where to get a Pin-Out Diagram for the wiring harness connector in the Firewall? Also, I am checking Grounds. I know of 4 primarily in the engine compartment, 2 from the Harness connecting behind the Headlights, 1 connecting to the fender near the EEC, 1 from the Cab (near the heater housing) to the engine, 1 from the engine to the frame, and the Negative cable from the battery to the frame.... am I missing any?

 

An additional one I add on Fords ... Between Motor and Transmission, this resolves poor starter ground issues.

This is what I say about grounds!
Grounds Grounds Grounds ...

In general ...

Ground cable between Battery and Motor. (Some Fords go Battery to Frame to Motor)

You should have ground straps between ...
Motor and Frame
Motor and Cab
Motor and Transmission
Frame and Bed
Cab and Hood (on some models)
Frame and Core Support

Think that covers it ...

And to quote Tom (tjc transport) "you can never have too many grounds. just not enough."

-Enjoy
fh : )_~