Fuel Injection - explain this to me like I am 6 years old

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Pawned

Pawned

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I am now getting 12.5 mpg on my 71 Duster 318 4bbl. It literally runs fantastic, finally.

I have been thinking about installing electronic fuel injection. Price is an issue for my wife at this point in time. Would like to keep it at $1,000 or less.

Does this sound do-able and would it be worth it? Would it dramatically help my mpg? What advantages is Fuel Injection.

I know very little about it and have not really started to educate myself on it. I know that on my other cars there are injectors for each cylinder, and the after-market seem to use one injector in place of the carb.

If it makes sense to do, I will at that point learn what I need to know.
 
Multi port injection is the more fuel efficient choice.
Throttle body type is much easier/cheaper to install but to my knowledge it has its limitations.without a good knowledge of efi i would work towards a more fuel efficient tune.
 
I would go on a limb and say that an overdrive transmission would be your biggest bang for your buck for fuel mileage.
 
A 318 with a Thermoquad can get get 20 mpg freeway in a light car with tall gearing.
 
explain this to me like I am 6 years old

Would it dramatically help my mpg? depends how well that carb is really tuned.. many think they are experts tuning a carb but in reality the car feels great but it isn't dead on.. if the carb isn't set up perfect (a carb can not be tuned perfectly at all times due to different weather conditions and altitude...etc.) then you can and will see improvement in MPG and power.


What advantages is Fuel Injection. easier starts.. it seems to mellow a cam out some, air/fuel adjustments in mili-seconds so you'll always have the proper mixture which is something a carb can not do..

gonna be tough to do for just a thousand dollars.. the fuel system can be pricey..
 
Got to be careful when spending money to increase gas mileage. A lot of the time its cheaper just buy the extra gas.

Id be lucky if I can drive my car 40 weeks out of the year. And even if i spend a $100 a week in gas and save 10% by going efi it will take me 10 years to break even more likely 15 years. I bought rhe holley sniper and fuel tank etc... $4000 Canadian so far. Still have to install it.

I mainly bought it for driveability reasons
 
don't know much about your car, but a simple 318 4bbl should be way better than 12.5 mpg. Find your issue. I've had built 360's with 3.91 gears that have done around 16 mpg.
 
Ok 6 year old, pull up a stool: EFI uses gas squirted into the intake in a very controlled manner instead of it being drawn in by the rush of air through the carburetor. EFI constantly checks the exhaust to see if there is any unburned fuel left and if it sees any it will reduce the amount of fuel being squirted (called a duty cycle) in to keep it very close to perfect combustion. The 2 different ways to do this is to squirt fuel into the intake manifold where the carb used to be, or squirt it down where the intake valves are so there is very little distance to travel. This is the prefered way to do it as the "mist" that the injectors create does not like to travel past turns and obstructions that are in a standard intake mainfolds runners. The shorter path makes it easier to burn as it is still very finely misted, while the longer path tends to recombine the mist into larger droplets, and that happens alot in a cold manifold on initial startup. You can pull a complete system minus intake for $250 from some other make (eg. Ford) also as long as you get all the sensors and get it from a motor thats about the same HP as yours is. Carbs are nice and simple and can run great, but EFI is about perfect in burning all your gas. So kids, do you have any questions? Ask your mother.....
 
everyone you talk to will say EFI won't make more power then a carb and its more about efficiently and drive-ability. but like that video shows thats only when the carb is perfect to your present conditions.. i think they could have messed with the carb a little more and got the power to match the efi but the next day when it was say more humid out and temps were different the carb would be off and th efi would be dead on still..
 
I agree with the idea of fuel injection. The easy starting and ease of operation I guess is What I am looking at. But in the same instance my 273 commando will be left stock with the carburetor. I am spoiled driving newer cars though
 
If you are only getting 12.5 mpg, something in your car is way off.
Hell my old boxy power wagon gets 14.5.
 
The Rochester model 220 TBI system is pretty easy to adapt to other engines. The typical small block throttle bodies flow about 500 CFM so it would be fine on a typical street 318. If you can find a late 80's GM truck as a donor, and do most of the work yourself you should be able to get it up and running for under $1000. Here's a good source of info "START HERE"--Fuel Injection FAQ--"START HERE"
 
A big advantage of typical fuel injection systems is the closed-loop feedback. Here's a good video on tuning an EFI setup and a carburetor.
 
Comments in the quote
Pawned said:
I am now getting 12.5 mpg on my 71 Duster 318 4bbl. It literally runs fantastic, finally. So what cam is in it? What gears? what Stall?

I have been thinking about installing electronic fuel injection. Price is an issue for my wife at this point in time. Would like to keep it at $1,000 or less.Not much available for that

Does this sound do-able and would it be worth it? Probably not an probably not.
Would it dramatically help my mpg? That depends on why your carb is so far off
What advantages is Fuel Injection. After the tune is in; driveability, fuel economy, engine life, lower maintenance

I know very little about it and have not really started to educate myself on it. I know that on my other cars there are injectors for each cylinder, and the after-market seem to use one injector in place of the carb.

If it makes sense to do, I will at that point learn what I need to know.
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As others have said.
 
Well that makes it official, your tune is just out to lunch.
And if it's a fat carb, she probably ain't making any power either.
Has she still got the factory single exhaust?
What carb and what intake,and what type of air-cleaner housing are you using?, or what did it come off?

That mpg number you quoted; was that steady-state hiway? and; With what rear gears,and What roadspeed or rpm?
With 2.7Xs say,and a 904, and 65=2285rpm (26s), and a 1971 spec engine with minimal leakdown, your mpgs should be at least 50% better.
To get hi-number mpgs with a carb is as easy as leaning it out until it misfires or surges; Then figuring out why it's doing that, correct it, and continue until it melts or breaks something. This costs you nothing but time and dirty fingers, and maybe a few low-dollar parts.
Geared for 65=2285, I'm thinking 20 is easily doable.And she'll have still more left in her.But you'll have to feed her fresh cold air; and then there'll still be more left in her.
 
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you can get a used FiTech 400hp/600hp system for under $800. They pop up on the FiTech Support facebook page all the time when guys upgrade or get frustrated dealing with the nagging problems.

If your mpg is struggling, then you have a problem. From my own experiences, going EFI won't solve problems, instead it will just amplify them. Before I installed my FiTech, I took my time and dialed the carb/timing in to the best of my ability. I just wanted a safety net to throw back on in the event I totally lost my mind since it was my first attempt at EFI
 
So how is it you have a totally stock 318 with a 4 bbl? A 71 318 had a 2 Bbl Carter BBD. What intake and carb are you running?!?

As other have mentioned, your MPG is way low. You may think it is running "fine" but there is probably room for improvement. Things to look at:
First: VACUUM ADVANCE is it hooked up, and does it work?
Second: Mechanical advance. Does it?
Third: Static timing. What is it set at, and is the mark on your damper any where close to reality?
 
Most of what you guys are saying is going over my head. I have not worked on a car in 45, years before I got this one. I have done all the work myself, short of rebuilding the engine, I would have done that myself but the shop was many months faster than I would have done it

Truthfully I am not into racing the car so I have not bothered to learn about the cam and such.
I have a MSD electronic ignition and the vacuum advance appears to be working just fine. It is hooked up to the port on the right of the carb. I do not remember which on that is, at this moment

The carb I am pretty sure is an Edelbrock 1406, I recently added new rods and jets on a friends suggestions, runs 100% better.

I did some additional tuning yesterday, seems improved. I was able to increase the vacuum about 13 lbs I am also having a hard time keeping my hand held tach operating. seems I have to open it up and do cleaning and soldering more than I should have to
 
273 said:
A lot of the time its cheaper just buy the extra gas.
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INDEED! You can buy a LOT of gas for $2000. Will fuel injection make your car start better, improve throttle response, and most likely improve gas mileage? Yes. But ultimately you have to ask yourself if it is worth the cost to you. Plus, do you only drive it occasionally, or is it a daily driver?
 
That 1971-318 was rated at about 9.2 or 9.5 compression ratio IIRC. The idle vacuum should be greater than 18 at 700rpm. It should idle down to 600 in gear, and I'm guessing, still better than 16". And these numbers are for the factory timing specs, which I think was TDC. The factory cam was a 240/248/112 with an IVC of 50*. If I got all that right, then

Static compression ratio of 9.2:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is 161.70 PSI
V/P (Volume to Pressure Index) is 133...............................................133

At 162psi, that 318 should run gangbusters, peaking at about 22inches or better with just a bit of rpm.
Assuming a decent LD, and a free-flowing exhaust;
Throw a bit of timing at it, then start leaning it out. Before you know it, you'll be at 16/17 mpg. Then bring the minimum running temp up to 195,and feed her some fresh cold air, and pick up another 1 or 2mpgs. Then try and get the cruise timing up to about 54* of timing at 2250 , and then your point to point should be approaching 20mpg. Then start leaning out on the cruise step until it won't hold a steady speed, then give her a bit back and Voila, I see 22mpg on the horizon.

But I gotta warn you;
If your compression is down, Or your LD is bad, or your exhaust is plugged, or your Dist is sick,or your tires are flat. or your brakes are dragging, or your tranny is slipping,Or your dragging the tires sideways down the hiway,or your running N50-15s at 20psi sticking 2 inches past the body-line,, well then maybe 12.5 is all she's got in her.
 
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AJ/FormS said:
Throw a bit of timing at it, then start leaning it out.
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The "book" says the timing should be a TDC. I have mine set at 10° BTDC because it seems to run so much better. Plus I seem to remember someone on FABO recommending going to 10 BTDC, and I liked it.
I think the idle vacuum was at about 15 at 650-700.
I have done some more tuning and leaning it out. I just need to get it on the road to figure out the mpg.

I truly do appreciate the information. But I am a retired electrical engineer and have not worked on a car (on even paid attention to the workings of the cars) for about 45 years. I think that would be about 1973.
That is why I titled this explain this to me like a 6 year old
 
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