Any advice on conversion of 1972 ls5 to fuel injection? Really need some input on this. Thanks.

 

You need to provide a bit more details. What type of FI are you looking at for starters? A Holley sniper is fairly straightforward and been done a million times.

 

My corvette came with a fuel tank meant for fuel injection and even has the fuel pump and everything, just sitting there not being used. Like others, I thought about going fuel injection because it is in all the magazines and car shows and you are told it is better. As I dug into it more, I am seeing a lot of issues with them. They are very finicky and the install needs to be perfect. There are a lot of rules to prevent damage to the ECU. A lot of systems do not come with a fuel pressure regulator and have fun figuring out which one to buy and where to put it. The Holley Sniper has it built in, which is convenient. But it also has the ECU in the throttle body, which can be prone to damage from heat. The Holley Stealth has the ECU separate and can be installed someplace cool. Edelbrock Pro Flo looks good, but require a lot more work, costs more and comes with more. So you can't ease into it with that system. For now I will stick with a carburetor and set things up for a possible future Holley Stealth system. But if the carburetor works well, I may just stick with it.

 

nyciti: Those are the questions I am looking to answer. Which system? Why? What improvements did you see, if any? Would you do it again etc etc etc.

 

Jayk47: Thanks for the input.

 

If you do a bit of search you'll find a fair few threads on this subject.
Including one I put up a couple years ago. "77 EFI conversion."
So, I've been running EFI on mine for about 3 years. Including some very long drives.
Recently I dropped an injector. And it actually took me awhile to realise it as it continued to run very well on the remaining 3 injectors. One new 50 dollar injector later and all is well.
Start up, warm up, and general drivability is so much better than with the carburetor. Don't believe there is a difference in power. Fuel economy is better as well.
I wouldn't dream of going back to a carb anymore than I would put on drum brakes.

 

4-vettes: Thanks for the input. What unit did you install?

 

I've converted all my cars to EFI and I will never listen to a carb is just as good...it simpler in theory. Sorry but that's from folks who don't know how to tune or setup a system. They are not that complicated at all. It's been around since the 80s in computer form in one way or another for GM.

Reasons to go EFI are ease of start in any weather, ability to run you car closer to the edge, comp for variation in gas, altitude and weather. Better gas mileage. And I'm sure a few others I'm missing. Others will argue.

 

I've converted all my classic cars to EFI and I will never listen to a carb is just as good...it simpler in theory. Sorry but that's from folks who don't know how to tune or setup a system. They are not that complicated at all. It's been around since the 80s in computer form in one way or another for GM.

Reasons to go EFI are ease of start in any weather, ability to run you car closer to the edge, comp for variation in gas, altitude and weather. Better gas mileage. And I'm sure a few others I'm missing. Others will argue.

 

I too would be interested in the specific EFI systems you are running if you have had good luck with the system. It seems like every EFI review I have seen indicates several issues, including ECU failure, which means your car is a very large paper weight until it gets fixed. Also if something goes wrong, parts are not readily available at typical car parts stores.

I would also be interested in hearing how much you swapped out for EFI. For example, did you swap out the distributor as well and allow the ECU control timing? And if you did do that, did you modify the timing? Some reviews note that the timing curve with the ECU controlling the timing is very sudden and not linear. With my specific vette, the distributor drives the tachometer by cable, so switching out the distributor is fairly expensive once you account for cost of converting the tachometer to electric as well. I was initialy going to go Edelbrock Pro Flo, but by time I accounted for the tachometer and the fuel regulator, it was $3000. The Holley Stealth seems to allow for many configurations and you can do the transition in steps, starting with stock distributor and upgrading later if you want.

There are a lot of options out there and another thing to consider is the ECU interface/app. I guess Edelbrock and Holley are pretty nice, but some others are not.

 

I've used various efi systems and retro fitted many GM systems. A large key to efi is it's electronic and requires GOOD wiring and GREAT grounds. I can't tell you how many people cut a corner and then wonder why it doesn't work or blame the system. I don't see the value in efi without controlling the timing. In that case I would stick with a carb. To be fair all my vettes are modified so the cable tach isn't something I worry about.

If I had to recommend a system it would be a Holley one, I've had great success with them and their is ton of support on the Holley forum. I run a supercharged SBC in my vette. (See my build). What is your engine and goal for the car? EFI isn't cheap but I think worth it. If you have a perfect running car and don't drive it much might not be worth it.

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Your question is somewhat the same as "how much is a kitchen remodel" - What are your plans and goals? What engine/tranny are you running? Is this a fresh rebuilt high revving big cam motor?

I started putting simple Haltech EFI systems on my big cammed boat engines years ago. The big difference was in not fouling plugs through the "no wake" zones.

I put a Holley C950 system on my fresh crate motor Fastburn 385 around 20 years ago. It is not the same as the modern units that Holley uses and is a batch fire system. I spent a lot of money on it and built the fuel maps myself, but I enjoyed that type of stuff back then. I live in CA and my car was built to be a track car but ended up being a fair weather puff cake fun weekend car. It ran fantastic with the old Holley carb but I took the time to tune that carb. That EFI system at that time was not worth the money. I am now "pot committed" to EFI on that car and will be updating to a new Holley ECU which is a true sequential system and will control the timing. It is still rather expensive at around $2.5k for just the parts.

For comparison, I purchased a complete Gen V LT 5.3 AND 8-speed automatic with the ECU and complete wiring harness for $2.5k for another project. If my Fastburn 385 ever blows up, I will swap it for a more modern LS/LT engine which are just better engines and I am an old BBC guy!

So, what is your setup now and what are your goals/wishes? EFI wont cure a turd engine or bad parts. EFI is not going to give you any real "seat of the pants" performance improvements. EFI can help tame some big cams and help with cold starts (are you driving your old Vette in the snow?)

I just reread the OP's question and noticed that he has a BBC car. If it runs good on the carb, I still wouldn't bother as that LS5 is a rather mild cam. If it were my car and that LS5 grenaded, I would pop a LS/LT in it.

 

Hello there delandjohn,

There are a lot of choices out there so making the right choice is even harder with the various options. There are companies like Edelbrock and Holley that make fuel injection systems and when I started looking I was looking for two things. First I wanted a system from someone with actual experience with fuel systems and not a newcomer with questionable parts. I started thinking about a Multi-port Fuel Injection system and thought that was the best as that is what most cars use in this day. I have a 1968 C3 with it's 427 and there are certain limitations that I was stuck with unless I wanted to buy a new hood or other major parts. I needed a Carburetor replacement to be in the precise spot the carburetor was mounted in to use the hood I have. I am using a factory L88 Hood on my 1968 and I really did not want to step back to the original Big block hood.
The systems out there using a Multi port all use an injector per cylinder and a simple throttle body. These require the ECU to be mounted someplace away from the parts and have more complex wiring harness'. One concern was putting a EFI system on a 1968 without making the engine look like it was an EFI engine. This made me look at the throttle body systems like the FiTech and the Holley Sniper as they would be easier to install and not make the engine compartment look like it was out of a new car. Some people wonder whether a throttle body system can get even fuel distribution that a Multi Port system could deliver. Then I remembered all the Chevrolet vehicles made with the twin injector throttle bodies like my wife's old Chevrolet Pickup had. They had even fuel flow and worked very reliably for close to 300k miles. In the whole time we owned the Pickup truck we never touched the fuel delivery systems and it worked great and got good fuel mileage. I was particularly interested in the Edelbrock Pro Flow IV system which was about $2400 just for the kit. It had a new intake manifold with injectors installed and the throttle body. The technology looked modern but it was going to be a task to install and set up even with the self learning features.

The most important thing for me was then "What happens after I buy a system and the installation is done but I have problems with the software or something else". I like many of us had heard lots of horror stories about EFI systems that did not ever work properly and the owners either had to have it towed to a specialist who then charged you dearly to fix the problems they were having or spent many hours of time on the telephone waiting for someone that had the knowledge to help them. After speaking with a few friends and mechanics I started looking online for dealers that supported the customer AFTER the sale. This is when I learned about EFIsystempro down in Florida. They offer the best price and 2 years of tech support without having to contact Holley Tech Support.

I had my 1968 which was running okay with the carburetors but had issues starting in the colder weather. I suspected that to switch to an EFI system I was going to have to buy a new fuel tank as well as the other parts. Starting at $2400 another Fuel tank put the total at over $3k and it was getting harder to justify and get permission to dump a lot of money into what appeared to be a money pit on wheels. I then gave myself a budget of $2500 to buy a system IF I could find one that I could afford at that price. The day I called EFIsystempro I was ready to spend $2500 but after after speaking with the salesman I was told that I could simply change the fuel tank sending unit with a Holley In-Tank Module that included the sending unit, Electric Fuel Pump and Fuel pressure regulator. This meant no $600 for a fuel tank and that made me more interested. The system I wanted was a Sniper but in keeping my replica L88 engine looking like it should I went with a Holley Stealth Sniper which looks just like a Holley Double Pumper and had the electronics inside it. With the Stealth Sniper there were very few wires to install. 2 Power wires, a new Temperature sending unit that went in my intake manifold's unused hole, a new Oxygen sensor wires and a wire connecting my MSD 6AL and MSD Billet Distributor ignition system. The salesman gave me a total parts price of close to $1700 so I actually saved several hundreds of dollars buying a Holley Stealth Sniper and the Holley In-Tank Module. I was shocked at the fact I was heading for way less than I had intended to spend. I was still concerned about the after the sale tech support when the salesman told me that if I bought from them I would get 2 years of Post sale support from their own In-House Holley Tier Three Tech who would ensure that I got my system and had it working before I was done. I went ahead and bought the system using PayPal to spread the cost for a few months. I received a e-mail from the Tier Three tech before the parts arrived and we spoke for a few minutes getting to know each other and talking about my intended project car. Before getting off the phone the tech gave me his cell phone number, his email address and told me that I should call him if I had any problems. The tech then went on and gave me some great advice on how to get my system working right from the beginning. He suggested that I connect the system and only do the fuel Injection part of the install first so I didn't compound the problems by connecting the ignition system to allow the Holley Software to control the timing of the engine as well. My system arrived two days after I ordered it and was complete with everything I needed to make my Corvette Fuel Injected.

That advice was followed and it was a very smart move. Today I am involved in helping people with their Holley EFI systems and problems they are having. By installing the system in stages you avoid strange problems that can occur. My engine still uses the MSD Ignition system and has timing control. It is wonderful to have the engine running this way. Using the Holley EFI Software you can set up the timing curve and the fueling curve as well. My system was self learning and after getting it installed I had 60 psi of fuel pressure at the throttle body. Having the Fuel Pressure Regulator inside the tank I don't have or need a Return Line. It took me less than 1/2 hour to install and wire the Fuel tank components. The In Tank module used a piece of the Holley Hydra-Mat so sucking air at low fuel levels is not an issue. I was shocked at how simple it was to install the wiring for the entire system. The toughest part of the install for me was drilling a hole in my exhaust system to install the O2 sensor. They had included the right size plates for my 2-1/2" exhaust pipe so the clamp on or weld on plate was simple to install with no leaks. The entire system can be installed very quickly and getting the car started was a breeze, enter the engine size and number of cylinders and cam type and she started right up. It idled a bit fast so I set the idle and then adjusted the IAC valve according to what the Tech Chris told me to do and the car was ready to start driving. The only part I ordered afterwards was the progressive linkage for the throttle body, the original has all four injectors with all four barrels opening at one time and that was a bit too much for my 4 speed Corvette. The progressive mimics the throttle action of the Double Pumpers and makes it easier to get rolling without lighting up the tires every time.

In the end I would strongly recommend the guys at EFIsystempro for anyone who is thinking about an EFI system. The newer Terminator and Stealth Terminator are now available and have more inputs that allow you to program in any way to choose. My Stealth Sniper does not have any Knock Sensor input. I have a MSD Knock Sensor installed in my Corvette and will be adapting it to work with the Stealth Sniper. The Holley Software allows me to install a Nitrous system, either Wet or Dry very easily and is controlling my water/methanol injection system for my engine. Using 12.25-1 Compression I have it set up to run a hair on the rich side to prevent any issues but getting everything working turned out to be much easier than I expected it to be. Holley has been making carburetors for a long time and they have also been making EFI systems for many years. The equipment I purchased is of great quality and I suspect it will last a long time. The support I got was not needed anywhere near as much as I was afraid of before the installation. My fuel system holds pressure for a lot longer than my C4 Corvette's factory system can. Unlike my factory EFI system on the C4 the Stealth Sniper is very adjustable using the hand held touch screen or a laptop. I keep a laptop in the car hooked up so I have data from the road trips I take with the 1968 C3. One bad thing that the Sniper serious doesn't have is a real time clock, it has a timer that starts when the system is turned on but it doesn't have files for each day or from each drive on the same day. The newer Terminator series does have a real time clock setup so Holley is making advances as they move on down the road. I love my Stealth Sniper and unless I remove the original drop base for the L88 intake system you can't tell I have a fuel Injection system on the Corvette. If I were doing it from today the only difference in my case would have been going with the newer Terminator series. If you call the folks at EFIsystempro they will help you decide on what they think would be the best for your Corvette and they will advise you carefully. If you really want GREAT "after the sale" service there is no other choice in my mind.

P.S. I do not work for EFIsystempro nor do I receive anything from them for these recommendations. I do it because I have had an awesome experience with their help!

 

I'm cheap so I have done swaps using GM EFI systems. They do work well, and I like having the automatic transmission control integrated. I wouldn't run a carb again, tuning without lifting the hood is rather handy.

 

its very expensive and not worth the cost unless you can find someone to tune it and goive you a good fuel map. Find a local person that can tune it first, then look at getting one./

 

I would have to disagree with that statement above as I have installed my first one and it worked great and was very straight forward. Between the well-written Installation Manual and the software being "self learning" most installations are truly quite simple. I was protecting myself by purchasing a system from a company that had an expert available to help you throughout the installation and tuning. Today even after a couple price hikes by Holley the Stealth Sniper is $1237.95 and the fuel module is $393.95 making the system $1631.90 That is not "very expensive" in my book and I am "cheap" in comparison to many Corvette owners we read about here on the Forum. Getting the systems set up is again not that hard to do as the system is "self-learning" and after it learns the basics you can turn off the self-learning and just enjoy the Car. They even offer a Sniper designed to work on a car equipped with a Quadrajet, it is a bit more expensive but you wouldn't have top replace your intake manifold.

But on the Forum and other places where I regularly help the owners of new Holley EFI systems, most of the guys are pretty much able to get it up and running without having to scratch their heads very hard. Holley has spent a lot of time and money to make it easier for us to install and enjoy the benefits of a EFI system. As you and I have spoken before I am still using the Edelbrock RPM Air Gap dual plane intake which I am using with my Holley Stealth Sniper. I have no whistles or any strange issues using this intake. I am running a very high compression L88 and even with that the Stealth Sniper's self-made fuel maps are doing great. I can very easily go in and modify them IF I needed to but I haven't so far. My Ignition system is not the "optimal" for the Holley EFI systems timing control but I still run my MSD 6AL ignition that sounds like a welder when firing a spark plug. It would have been easier to install a new Holley distributor but I don't need to as I like the really HOT spark that the MSD systems is capable of making.
I have seen and helped debug these systems installed on Chevrolets, Fords, Chrysler's, Mazda's, Jeeps, VW's and even a few Holden's. They make a Sniper for a lot of very unusual applications and they are all simple and inexpensive. I have helped people in a dozen different countries and they were all successful. I do get a bit peeved when people give up easily but it happens, with help not very often however. I am going to put one on my Boat just so I don't have to deal with the old carburetor it came with.

The Holley Sniper's one "weak spot" is that they are "sensitive" to EMI or any electrical noise that is induced into the wiring by not keeping the Power wires and Sensor wires separate. While building village power systems using large Solar PV Systems, Wind turbines and Diesel generators we used our own computer controllers and then I learned not mix "power" and "sensor" wires in the same conduits or wire molding. On a Corvette with the Fiberglass Hood we don't have anywhere as much trouble as the cars with metal hoods. The power wires are few and keeping them away from the Ignition system only makes sense. If you run the Coolant temperature sensor wire across the ignition wires there can be issues. The Terminators are a bit more expensive but have a separate ECU and can control transmissions along with many other features.

 

This is the reply that keeps me in check.

One could easily dump $10K into a Gen 1 SBC, and still not have something as nice as a cheap junkyard LS swap.

 

YOur not going to get any bettter gas mileage , any more power, and any more reliability. You will be able to turn the key without pumping the gas. Thats it. My quadrajet got better mileage on my small block and it wouldnt work on my big block dual plane. It works best with a single plane like all the factory manifolds.

 

I don't know Rogers. my small block definitely gets better fuel economy with my EFI compared to both the over complicated quadrajet and the Holley.
I can put the car in high gear at low speeds going up a steep hill. Never could do that with a carburetor.
I've had mine on a dual plane and a single plane manifold.
Really can't tell a difference.
And the OP asked what system I am running. Guess he didn't read my thread.
I'm running the Summit MAX 500 system. Made by FiTech for Summit Racing. basic EFI system that has a remote ECU (Not mounted on the throttle body). and does NOT run timing. I have a DUI HEI that does that brilliantly.
A lot of people on here say you want the engine management system to run the timing.
I say keep it simple.
As per finding help tuning. I find it much easier in today's world to find tuners experienced with EFI than it is to find a carburetor expert. Most younger Mechanics/ Tuners have little or no experience with carburetor's.

 

Glad it works for you. What was the final cost of everythimg. The fuel tank , pumps, filters , fuel lines, labor hours, tuning, intake changes, system. Ik ow there is a lot of associated costs and it isnt cheap. I wanted itfor its self tuning for cross country trips.
That isnt really feasible at this point