Fuel Injection vs. Carburation

Has anyone else gone the route of foregoing normal aspiration in favor of fuel injection? I am taking a long hard look at all my options for this car and I certainly want the best drivability and performance I can get out of my Cleveland.

Thoughts and suggestions on a system?

Personally.........

I think injection is a nice idea... if you had all of the components at hand.

For a part-time driver car, Dad's Tiger knocks down 20+mpg and it is bone stock with the addition of a controlled leak for a 4V carb and cast iron intake. It has zero issues, whether driveability, heat, starting, etc. Keep in mind, too, that the modern ethanol BS in the gasoline is not friendly to standard carbed components.

My 5.0 is also bone stock. It too knocks down some nice, 20mpg-ish cruising mileage. It too has no issues.. But, I can see if/when something does malfunction (IAC valve, throttle body, injectors, O2 sensor, etc.), the repair cost will surely be more than any carbed repair that I can think of.

Again, IMO, if you're a gadget freak, go for the injection. If you're a cheap, old skool sucker like me, stick with the carb. I really don't think there's a clear cut answer.

Mr. Mac - Fuel Injection is one modification to my 351C that I would like to try as well. It is just so expensive. I have read several good reviews of the Professional Products Powerjection system: http://www.summitracing.com/parts/PFS-70026/

Mesozoic has a EFI system on one of his vehicles and he may have some advice on the matter.

Let us know how it goes for you.

This reminds me of an old thread where downwardspiral made his own fuel injection setup.

http://www.7173mustangs.com/thread-megasquirt-2-v3-on-351c?highlight=megasquirt

My thoughts...

I had a throttle body injection (holley projection) on my mustang for a while. Ran pretty good overall. From a drivability/mpg point of view here is my order (worse to best)

1. Carb

2. Throttle body injection

3. Port injection (simultainious)

4. Port injection (batch)

5. Port injection (sequential)

6. Direct injection

My recommendation is if you are going to go fuel injection, go big. Don't just do Throttle body injection (TBI). While you may be able to tune it 'better' than a carb it still suffers from the same basic problem: Wet Manifold. Both a Carb and TBI mix the fuel into the air as it enters the intake manifold. Since the path to each Cyl is a different length and has curves the mixture that reaches the cyl is different for each cyl and will also vary with RPM. They try to design it so the paths are the same as possible and the curves as smooth as possible but in the end they are different. This means you tune to the most lean cyl. Every other cyl is getting 'a little more' fuel. So while you can get some improved drivability with TBI (somewhat depending on the kit, what inputs it has, who tuned it) you still have the wet manifold.

Wet manifolds are not a problem with port injection. The injector is right at the intake port. (Some would argue this is still a 'wet' system compared to direct injection). But you can shoot the exact amount of fuel needed right at the intake and get a much more consistent mixture from cyl to cyl. sequential is the preferred method since it times the fuel shot for each individual cyl.

Of course, our year motors were not designed for port fuel injection. That doesn't mean it won't work but a more modern engine is optimized for port fuel injection. The head design will take into consideration the location of the injector and will, all things being equal, be better than a head/engine that wasn't designed for port fuel injection.

That all being said, if I was going to return to fuel injection I would go port fuel injection and focus on a system that is sequential. The downside is they tend to be expensive, you will not recover the cost in increased mpg.

Also, there are carb setups (webers) that, while wet manifold, are configured in such a way that it is minimized. And the look really cool too..

Anyways, that's my 2 cents. I am not an expert. I have run carbs and Throttle bodies on my Mustangs. I have done a lot of research on this but don't have any hands on experience with port fuel injection on a 71 to 73 mustang.

The cost/benefit ratio is not there unless money is not an issue and you are going to drive the car 12K a year for a long time. Just an opinion. Chuck

The cost/benefit ratio is not there unless money is not an issue and you are going to drive the car 12K a year for a long time. Just an opinion. Chuck

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+1 You're right on the money Chuck!

The cost/benefit ratio is not there unless money is not an issue and you are going to drive the car 12K a year for a long time. Just an opinion. Chuck

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I agree. Buy the proper carb for your application, get a wideband O2 meter and learn to tune it. You can actually get better mileage on the highway with a carb than with fuel injection.

The 'best' tuned carb will not get better milage than the 'best' tuned sequential port injection on the highway. The difference may be negligable but the wet manifold will make it all but impossible to deliver consistent air/fuel to all 8 cyl. Now, I am splitting hairs and it all is dependent on each system running as well as it can.

However, I totally agree that carbs are the way to go with our old iron. Port injection is going to run you a couple of grand if you do most of it yourself and almost double for a 'kit'. There is just no pay off in performance and no guarentee of results.

I have been doing a bit of reading both here and elsewhere and am starting to wonder if I shouldn't just proceed from where I am and just swap out the stock intake for a better one. I currently have a set of 2V heads (which I read have better low end torque) and that Holley sitting atop a Ford intake manifold (I'll try to get my son to get pictures of it all for verification of exactly what parts are installed). To be honest, right now I really don't know what I have as everything came to a screeching halt when they told me my job was going away and to go find a new one!



For a streetable Cleveland with decent take-off power I'm thinking that just cleaning it all up (to include a carb kit) staying with the 2Vs and adding a better camshaft and intake might just be the ticket to success. Or should I drop down to a 650 CFM Holley? Questions, questions, questions!

Well, it certainly is a Cleavland. Looks like someone put a later model air cleaner on it. When you say 'that holley' what are you referring to?

Performance is usually a 'package deal' with most parts getting matched up to CID/Stroke and the camshaft. For example, too much CFM on a stock cam will kill performance but might be the right size for a bigger cam engine. Once you swap out cams you are looking at springs. Once you are looking springs you are looking at replacing the crappy stock valves and it just goes on from there. Make sure you know which cam you are choosing and the lift on it. Most will tell you if you can run stock springs or not.

At first look at the carburetor sitting on the intake it appears to be a Holley 750 but I need to clarify that by its part number. As for the rest of the engine I already planned on a complete head job (new valves, springs, rockers, guides, seats, etc.) for this motor. A local shop here can do it all for about $600 (plus or minus depending on parts). Then the block will get completely reconditioned and new cam bearings, freeze plugs, yadda, yadda...

I am going to have to take my time and do this as the money allows but I won't just rebuild it on a shoestring budget as I want it to last. My plan is to drive this car, maybe not daily but it will see some miles each year!

If you are going to swap out the cam bearings then swap out the cam too. Take the fuel injection money and get a hyd roller cam. Match the valve springs to the cam. Get some really good valves.

Figure out which cam you want based on how you are going to drive (and how often) and then pick out the rest of the parts based on that.

If you are going to swap out the cam bearings then swap out the cam too. Take the fuel injection money and get a hyd roller cam. Match the valve springs to the cam. Get some really good valves.

Figure out which cam you want based on how you are going to drive (and how often) and then pick out the rest of the parts based on that.

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All already in the works! I was looking at a .570 lift/282 duration Comp (SK32-238-4 $260 with new gears and chain) cam with mechanical flat tappet lifters, new push rods, valves, rockers, stem seals. Not radical by any means but should provide a fun ride.

Beefy cam! You should sign up on the 335 engine forum:

http://www.network54.com/Forum/119419/

They are focused on Cleveland performance. With that cam you will need an adjustable valve train and you would benefit from the 4v heads as a lot of your power will be in the upper RPM.

X2 on the 351C forum recommendation.

As a rule of thumb, tis better to undercam than overcam.

I'd guess that cam will require more compression as well. May require block decking as well as pop up pistons with the 2V heads.... the list goes on and on...

My Dad used to refer to decisions like this as "lighting the fuse". You need to know when to light it, and when to pinch it off...

Hey, as TheJ mentioned, I converted my car to efi. I went with megasquirt, which is one of the most universal and not so beginner friendly. I love it and am not interested in carbs anymore lol. I was a beginner and I did it as more a learning experience.. I soldered the boards together and modified some circuits to work with my car. Its definately feasible but it will take a while, and alot of time reading the megamanual. The car runs better than it ever did, I'm not sure what my gas mileage definately is because my speedo is off from a gear change. I am estimating it to be 15ish with 3.90's (3300ish RPM at 55) and it was running a little rich. I broke something in the steering and havent had the time or money to fix it so I haven't been paying much attention to the car.

I am estimating it to be 15ish with 3.90's (3300ish RPM at 55) and it was running a little rich. I broke something in the steering and havent had the time or money to fix it so I haven't been paying much attention to the car.

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Wow, I get 1/2 that! (3.50 gears and a tri power) I guess three carbs is worse than one FI.

Well, I figured out what's sitting on top of my intake! It isn't the 750 I thought it was, rather a 600 double pumper! At least I now know what it is. Now I just got to figure out if that's what I want to keep on top!