EFI conversion questions

[Huicho417]

I have been thinking about the Holley Sniper EFI conversion for some time now. Recently I converted my 318 from the original 2 bbl carb to 4bbl 1406 Edelbrock. It runs great now, but I do have to do some tuning from time to time as weather changes. My curiosity is mostly to avoid the tuning from time to time and to possibly get better mileage. Also, every video that I see seems to yield some very positive results with startup.. Has anyone done this conversion, and what have been the outcomes?

I know I will have to convert my mechanical pump to electric, just not sure the best place to mount that. It would be great to see pictures of the install if anyone has done it. My current fuel line is 5/16" supply and I have added a 1/4" return to get rid of vapor locks (which by the way did work). The EFI recommends 3/8" supply so not sure if i will have to change the sending unit and steel line size.

Thank you in advance for your suggestions

 

[gkent]

3/8" line for a Sniper ?!?!

 

[JimKueneman]

My opinion, don’t do it. I did it on my 318 Coronet. Quickly you learn the fuel delivery system needs its own engineering and costs much as the EFI unit. If your carb is tuned correctly there is no MPG gain. Auto learn is a marketing gimmick. This only applies to steady state constant throttle Air Fuel mixture. All other drivability adjustments need to be figured out. Factory engines spend thousands of hours on dynos to get these adjustments dialed it for all conditions. If it dies on the road what do you do? Tow it home and send it in for repair for weeks one end or buy a another one. I have built 3 cars since and have put carbs on them. The ONLY improvement is the EFI car will start instantly after a hot soak and the carb cars need the loving touch. I carry a carb kit, float and fuel pump in the other cars and in an hour I can likely be back on the road with out EFI. Was not worth the time and money invested in my opinion. Better off getting an air fuel ratio meter and put O2 sensor bungs in the exhaust and dial the carb in precisely .

Few that have spent the $$ and time to get their EFI working are going to say it’s not worth it after the fact. I have 2 fresh 318 cars side by side in the garage and the difference is not worth thousands spent and hours spent on the EFI in my opinion.

 

[451Mopar]

Don't think of EFI as a carb replacement, more of an entire fuel system, ignition, and gauge/sensor replacement.
The EFI will get clogged easy if trash/rust gets to the injectors and regulator, so a good clean fuel system with EFI filter is needed.
My first setup used the external pump with pre-filter and post filter, and it worked fine, but the appearance and sound were not a good as an in-tank pump setup.
The in-tank setup seems quieter, and looks cleaner and more simple as the pickup sock acts as the pre-filter. Also being in the fuel the pump should run cooler.
All my EFI setups use a return line. I haven't tried a setup with the regulator at the pump.
On the TBI all-in-one units like Sniper and Fi-Tech, I run a thick base gasket to try getting heat away from the unit where the electronics are. Having the fuel cycle through the unit using the built in regulator and return line should also help keep the unit cooler.
Compared to a carb fuel system, don't expect the fuel pressure to be steady. The regulator pressure is referenced to manifold vacuum. The idea is to have a constant pressure across the fuel injector so the injector rate remains constant.
If using stock type intake and manifold with the heat crossover, you could likely block the heat crossover too.
The EFI needs an O2 sensor in the exhaust system, and the exhaust system should not have any exhaust leaks.
The EFI will monitor the O2 Sensor, the Engine Temperature, Engine RPM, the intake air temperature, the manifold vacuum/pressure, and throttle position.
Most of these units can also data log the sensors.
I like that many units will control the ignition timing. It allows a high control of the ignition advance curve.
The ignition signal from the distributor occurs around 50-degrees before the set base timing, and the ECU delays the spark out the correct time to acheive the programmed ignition timing. Because of this the distributor needs to be locked out of having any advance, and the rotor phasing needs to be modified.
On my Fi-Tech in the Charger, I am using a inexpensive factory lean-burn distributor.
On Mikes Coronet with the Sniper, he used all the Sniper Hyperspark distributor and ignition box.
On my Coronet with FAST 2.0 port EFI, I have a FAST dual sync distributor. You only need a dual sync with sequential port injection.
That is sort of the basics. Not getting into crank triggers and individual coil per plug stuff.
Some items most EFI include that would be extra control boxes are rev-limiter, Electric Cooling fan control, A/C compressor idle compensation, and some will control power adders depending on the ECU unit.
The higher end ECUs can be wired to read a flex-fuel sensor to modify tuning for the amount of alcohol in the fuel, some have traction control, and other features.

 

[gkent]

Wow, the sceptics are out in force today !!

 

[RJRENTON]

My opinion, don’t do it. I did it on my 318 Coronet. Quickly you learn the fuel delivery system needs its own engineering and costs much as the EFI unit. If your carb is tuned correctly there is no MPG gain. Auto learn is a marketing gimmick. This only applies to steady state constant throttle Air Fuel mixture. All other drivability adjustments need to be figured out. Factory engines spend thousands of hours on dynos to get these adjustments dialed it for all conditions. If it dies on the road what do you do? Tow it home and send it in for repair for weeks one end or buy a another one. I have built 3 cars since and have put carbs on them. The ONLY improvement is the EFI car will start instantly after a hot soak and the carb cars need the loving touch. I carry a carb kit, float and fuel pump in the other cars and in an hour I can likely be back on the road with out EFI. Was not worth the time and money invested in my opinion. Better off getting an air fuel ratio meter and put O2 sensor bungs in the exhaust and dial the carb in precisely .

I totally agree with your premise.....the phrase, from the OP, "Also, every video that I see seems to yield some very positive results with startup".....shades of the old P.T. Barnum expression: "there's a sucker born every minute" may be applicable (what else would you expect them to say?....our system is mediocre at best?).....they could have said "our system is better than sliced bread". The conversion to EFI (TBI or DIRECT INJECTION) is an all encompassing change.....that is an engineered package with all pieces and parts coordinated to compliment each other.....this is direct conflict to "my buddies best friend's" rule. Just be sure of your overall goal and expext to pay more than you budgeted.... Just my opinion of course.
BOB RENTON

 

[Don Frelier]

I'm not opposed to EFI. I put it on the Charger and I still have a carb on the Plymouth.
If your carb is set up correctly the only changes if any that need be made would be a maybe a slight metering rod change and maybe if any idle mixture screws.
Otherwise yes it will run better in some atmospheric conditions than others. For me cool and damp always made more power.
And yes the warnings about EFI are valid. Throttle body EFI systems are a compromise direct injection is the ultimate.
But I enjoy playing with any kind of fuel system.

 

[451Mopar]

Bob has a good point. EFI is a different type system, and there can be a steep learning curve.

 

[diesel_lv]

I have Fitech on my 496. I wanted something that could start and idle at 850rpm in any weather or elevation on a medium built engine. I see 10mpg. Was it worth the cost of the EFI and the complete fuel delivery system, no. I'm sure I could have gotten a higher end carb w electric choke and tuned it to do the same.

 

[threewood]

I installed a Holley Sniper in my 69 GTX and am beyond happy with it. If you drive your car, especially in the summer, it will be a benefit over the open carb system. The EFI is sealed so the gas isn't going to evaporate out and cause hard starts. Throttle response on it is noticably better.

Get an EFI tank with in-tank pump.
3/8" feed
3/8" return
EFI filter
Solder all wiring connections and follow the directions to install

Link to my install thread...https://www.forbbodiesonly.com/moparforum/threads/i-finally-did-it-efi.207831/

 

[diesel_lv]

Are you keeping the 318? Is it pretty much stock internally? If so, a tuned carb should not need adjusting. I had many cars in the 80's n 90's that were from the 60's n 70's with a carb. Pump 3 times in the winter and start and idled with nothing else done. Drove from NV to VA many many times, and not one ever needed any adjustments due to elevation or weather. As mentioned above, get a $200 A/F ratio gauge and dial in your carb for 14.7:1. Ensure you have a very strong spark that will allow you to open your plug gap to 0.042 and you will see pretty good gas mileage w that 318.

 

[HawkRod]

I added a FAST fuel injection system to my 70 Road Runner along with computer controlled timing, and it has worked great for 7 years so far. I have written about this before, but here are my opinions on fuel injection

• I think in many cases fuel injection gets a bad rap because it was installed either poorly and/or without all needed components. As 451mopar said, it is not just a carb replacement. If you are going to do fuel injection, then you need to do EVERYTHING for fuel injection or not at all. This includes an in tank fuel pump, supply and return lines, and quite frankly, if you are doing that much you should control the timing too. It can't be "thrown in" but must be carefully installed both mechanically and electrically.
• My recommendation for many is to stay with a carb. Why? Not because FI sucks but because it is time consuming to install, takes some engineering and it is expensive. If you are merely driving around town, then a carb works fine.
  On the other hand, if you are going to be doing extensive driving and/or in varying weather, and/or especially at different altitudes, then a fully designed and implemented FI system will provide some great benefits.

 

[BeepBeepRR]

I have done 6 installs and only 2 issues same issue 2 different cars. The Holley branded 02 sensor took a crap. Holly replaced them. I bought an aftermarket one as well just to have as a backup. Other than that no issues. But you can't please everyone and some guys are DIE HARD CARB guys which I understand. Carbs have worked for a long time and are still a main stay in the classic car scene. But when you get in the car and don't have to pump the gas or wait 20 minutes for the car to warm up enough to roll. There is something to be said for the reliability of Fuel injection.

The fuel system portion of the setup is not as difficult as some would have you believe. You can either buy an EFI tank or you can buy a Holley EFI in tank fuel pump. Depending on your car it will look almost exactly like an OEM fuel sender except it will be an EFI rated electric in tank pump. But on Ebay you can buy an EFI tank that has everything you need to get the fuel supply end of the deal going. Then its on to the Sniper install and wiring this portion of the work is the most time consuming if you want a super clean install.

 

[matthon]

I used the 'corvette' fuel filter regulator and mounted it near the tank with an in-tank pump. New Tanksinc tank, ptfe fuel line with Fragola fittings, which are incredibly easy to install.

It is a commitment to upgrade other components, electrical, fuel, etc. Don't expect to buy a throttle body, install, go.
It needs to be fully thought through and planned.

I drive whenever wherever.

 

[451Mopar]

I have Fitech on my 496. I wanted something that could start and idle at 850rpm in any weather or elevation on a medium built engine. I see 10mpg. Was it worth the cost of the EFI and the complete fuel delivery system, no. I'm sure I could have gotten a higher end carb w electric choke and tuned it to do the same.

The Fitech on the Charger was actually bought for a milder engine build, but Everyone was saying you have to build a mild engine with less overlap and high vacuum to run the EFI. I threw the unit on the Chargers 12.4:1 compression 500" stroker with a large 272/[email protected]" cam. 0.726" lift, and about 4" of idle vacuum.
It took a little extra tuning of the ECU, but drivability is way better than trying to run a race carb on the street. I'm pretty sure the race carb might be quicker at the race track, but I do more miles on the street than the track.

EFI costs vary quite a bit, but so do Carb setups.
The Fuel system (carb, regulator, pump, and filter) that was on the Charger was as much or more expensive than the EFI setup, not to mention the cost of all the carb tools and tuning parts.

Some of the carb tuning parts I was using:
Quick Change fuel bowls with the special jet holding screwdriver.
The nice float bowl adjusting tool.
Assortment of accelerator cams
Assortment of secondary springs
Assortment of pump discharge nozzles.
Holley Jet Assortment.
Holley Air bleed assortment
Holley restrictor assortment
assortment of power valves
Jet extensions for the rear jets (with a notched float.)
On the CarterBrocks,
Assortment of jets
Assortment of metering rods
Assortment of step up springs
magnifying glass to read the part numbers
Pin gauges, drills, and micrometer for measuring rods and jets, and making different opening sizes.
Not to mention all the metering plate and fuel bowl gaskets.
All those tuning parts and tools cost as much as the EFI, but were accumulated over 40 years.

 

[F4R/T]

KISS, simplicity is what you will miss when the China made brain box leaves you walking and you have no cell service. There she sits along the road as you walk.. The choice is yours best of luck.

 

[BeepBeepRR]

KISS, simplicity is what you will miss when the China made brain box leaves you walking and you have no cell service. There she sits along the road as you walk.. The choice is yours best of luck.

You are not wrong there. None of the systems I have installed have 30k miles on them. So we don't exactly know the longevity of the components. The first one I installed was on a 1969 GTX and JJ put a bunch of miles on that car. That was one of the cars with 02 sensor issues. The other was the Roadrunner. It doesn't have a ton of miles on it due to doing other stuff to the car so it has not seen a bunch of street time.

 

[diesel_lv]

I have had my Fitech for 2 yrs now. I am not against fuel injection. It is amazing technology. Mine runs great, but I do not trust it to drive cross country. 1st issue was kit provided inline fuel pump, burned up w/in 2 weeks and left me stranded. 2nd was coolant temp sensor was reading incorrectly, replaced w acdelco sensor and it worked. 3rd was MAP sensor gasket was installed pinched. Replaced w new gasket and fixed that problem. 4th the ECU finally quit working. That was replace under warranty even though it was 3yrs since purchase as they know there is an issue and have redesigned it. After these 4 different issues, all quality control issues, it does not give me a warm fuzzy feeling. Yes, there are bad batches in anything. Just that buyers should be fully informed before purchase.

 

[64fury74charger]

I recently installed the Sniper system on my 74 Charger with a 400 that’s pretty much stock internally. I spent considerable time researching and looking at the best way to literally replace the entire fuel system and then install the efi.

I went with a complete efi tank for a 71-72 Charger along with a 10 micron filter right off the tank and ran new fuel lines up to the firewall. The sniper efi was pretty straight forward to install and also converted to lokar cables for throttle and kick down.

I drive this car a lot and Seattle is known for traffic congestion.
As stated already here starting is simply waiting for the handheld to load and turn the key. So far for me this has been worth the investment. Nothing was wrong with the Edelbrock that was removed. The original tank needed replaced anyway.
I did not have any hope for mileage improvement as that’s not reasonable for my car. It’s all about your expectations and how you do the install and clean, clean and clean are a must. Doing the install Yourself is a great experience and you have control over the outcome. Just my opinion and experience and that’s all.

 

[451Mopar]

I don't have that many miles on my EFI either, and question the quality of some of the parts.
Also with EFI, there are different types. The first EFI unit I had was the old version of the Edelbrock XT EFI, and it used a narrow band O2 sensor, and the ECU was very simple and crude by todays standards. It was also much more expensive back then. It almost turned me away from EFI too.

The new TBI systems with the built in electronics like FiTech and Sniper really brought the price down and made wiring and tuning much more easy.
Having the electronics in the throttle body makes for a cleaner and simple install, but Electronics don't like high heat that is why I try to keep the throttle body cooler on those units. With the remote mount ECU, heat is less of a problem, but you have many more wires to route and connect.

Reliability of EFI is related to the quality of the parts and how they are installed. New cars are EFI, and usually have no problems.
I have to say, I have had more breakdowns with carbs and points ignitions than with EFI and electronic ignition systems.
Just about all the EFI parts like sensors and Injectors and even Fuel pumps are just standard parts found on most newer cars, so it should be pretty easy to get replacement parts, except for the ECU.