EFI conversion questions

[Wietse]

If it runs good and you are happy with the way it runs i would stick with the carb, the minor tuning you require to do for the weather changes are nothing compared to efforts and costs of changing over to EFI.
You probably already found out that is not "just" installing that throttle body, a fuel pump ,fuel lines, electrical system, O2 sensor all come with it.

I did swap to a Holley Sniper EFI, though i have had my many sessions with a lot of help from FBBO members to get a decent tune on my engine and have never ended up with a good one. I've seen the lean and rich spots all over the rpm/load range and always was fighting idle quality vs. a pig rich cruising AFR or running damn lean at WOT.
I did not build the engine, and therefore it does not have the camshaft i would prefer (yet), with an LSA of 108 deg and of decent duration and a manifold vacuum of 7" i never managed to get a good tune for all conditions.
I had a 4 barrel double pumper, which i changed to a 4 barrel with vacuum secondary but still had to fight with it.
You could ask, why not change the cam? I know, but i am in the high compression ratio and a milder cam will get my cranking pressures very high, very fast....just the way i bought it.
The Sniper does a good job for me maintaining a nice AFR overall and (once warm) keeps a decent idle quality. (never seen these clean spark plugs before coming out of my engine)
I say decent because it tends to hunt rpm's at idle from time to time, this is one of those things that can be solved by a few adjustments.
A cold start will still require my intervention by keeping the throttle a little open until there is a bit of heat in the intake manifold so the fuel actually ends up in vapor form in the cylinders instead of puddling up in liquid form in the bottom of the intake.
So those easy start ups are not always there, the video does not show you the real first attempt on starting LOL.
Fuel consumption is just as **** as before, don't expect miracles

Thing is with this EFI is there are soo many options and settings to change to adjust things, i ran a data cable from the sniper to the glove box to hook up a laptop for datalogging and doing adjustments.....how many times i done that so far? Never, why?
Because once the nice weather is out there is just want to get it on the street and drive it and enjoy the ride instead of screwing around with fine adjustments.
That said, i need to and i will get more into it but it is not with a vacuum gauge and a screwdriver...you need the damn 1000 page instruction manual to read and figure out what you need to change for what you want. (its not rocket science, it takes time and patience....that last one is my problem
As i mentioned above, i still have some minor issues that can be improved but still need to get to it.
What i want to say is that you will receive endless options on adjustability and fine tuning, but most of them will never be touched once it runs good.
If the engine runs good with a carb, has a good matching cam for your wishes/driving style, just enjoy that short time you spend with a flat screwdriver and a vacuum gauge under the hood when tuning it in for the season.

 

[HawkRod]

Does EFI add some complexity? Of course it does. But at least my FAST EFI system (and I suspect all the others) use standard, typically GM, modules. So if one goes bad, you probably have a better chance of getting that module at Napa than you do an Edelbrock carb gasket!

So the reliability of EFI systems does not worry me.

After I installed my FAST EFI system I drove my Road Runner across country. My 383 Road Runner achieved an overall average of 17.2 MPG over 5,800 miles for the trip. Overall meaning not just highway miles, but ALL driving for the whole trip. In addition, I discovered I had a fuel vent issue so I was pissing a gallon or two of fuel out the vent when I filled it up, so my actual mileage was probably better. And we didn't drive like granny either. That's pretty darn good fuel economy if you ask me.

Like anything in life, there are pros and cons. Carbs and a EFI systems have their own set of pros and cons. Both systems, properly set up, can work really well. Both systems, poorly installed or setup, can run like crap. And neither system can miraculously take an engine in poor condition and make it run well. So think through all the pros and cons and make your mind up as you choose. There is not one right answer.
(By the way, I am going to do another trip across country and this will be with a carbureted 73 Road Runner, so I have both types, and use both types. )

 

[451Mopar]

Thing is with this EFI is there are soo many options and settings to change to adjust things, i ran a data cable from the sniper to the glove box to hook up a laptop for datalogging and doing adjustments.....how many times i done that so far? Never, why?
Because once the nice weather is out there is just want to get it on the street and drive it and enjoy the ride instead of screwing around with fine adjustments.
That said, i need to and i will get more into it but it is not with a vacuum gauge and a screwdriver...you need the damn 1000 page instruction manual to read and figure out what you need to change for what you want. (its not rocket science, it takes time and patience....that last one is my problem

That is the steep learning curve I mentioned.
I had to do many adjustments for the Idle Air Control on the Charger with the big cam.
I still have not taken the car to a chassis dyno to fine tune the system and ignition curves. I did this also, when I was running a carb and traditional distributor.
For me I noticed the self learn is good for off idle, cruse tuning the fuel curve where most street driving is done. On a carb, this would be transition circuit, power valve vacuum and PV restriction tuning which many people don't change because normally those restrictions are a fixed size and would need to be drilled or restricted unless you have a race carb or metering plates that is drilled and tapped for screw-in restrictors.
Same with accelerator pump shot. Many never change the accelerator pump cam or discharge nozzles in a carb, and just get used to slight stumble and hesitation on carbs not correctly tuned. Many will change jetting to cover-up the fact that the other circuits are not tuned correctly.
Just saying that fine tuning a carb is just as complex as tuning EFI, but because the adjustments are more difficult (time consuming, and needing extra parts and tools) most average users just ignore tuning those circuits. With the EFI, they are easy and quick to change, but also easy to screw up.

 

[Wietse]

I tried everything on my carbs until the point where i realized i need a carb with replacable air bleeds and restrictors.
So instead of buying a 3rd carb i went for a Sniper EFI.
The self learning works well indeed on driving conditions, during cruising it runs nice and lean, cold start and idle remain a little problematic.
Hitting the GO pedal it reacts crisp and fast and feels powerful.

But since OP has a good running engine from what i understand, i would just stick with the carb.

I had to do many adjustments for the Idle Air Control on the Charger with the big cam.

For me the same, i already did some adjustments which reduced the rpm "hunting" a lot better (reaction time of the IAC too fast) but i am sure there are more improvements to be made. (incl. a new torque converter that is "loose" at idle to get rid of the engine load)

 

[rolling_Thunder]

EFI is overkill for most people... if your engine runs well as is then just keep the Carb... I am running an MS3X on my 68 Charger because I did a Gen III Hemi swap about 12 years ago and I just recently found the Holley Hemi Terminator but decided to keep pressing with the MS due to my own stubbornness and my desire to learn much more about EFI systems and programming....

If I was running a SB or BB I would definitely just slap on a carb and call it a day.

 

[AMX364]

Now my 2 cents worth. How about a hybrid system using carb and in tank electric fuel pump? The in tank electric pump solves the gas boiling out of your carb and hot start issues. The only tuning that your carb should need is when the seasons change. Electric chokes IMHO are a god send, at least as far as heat crossover is concerned. The TBI factory cars used a 8-10 psi pump which can be controlled by most all cheap pressure regulators.


So is this what I am going to use? No, me going to MPFI using a Edelbrock Performer intake and the Holley Terminator X. Cost SO FAR is about 3-4000 and rising. It did not help cost to go with a Air Grabber system. Why a low rpm dual plane intake? Car has 2.69 gear gears and will likely rarely get above 5000 rpm ever.

Snipers sometimes have issues with dual plane intakes. Research that, if you have a dual plane intake. Most have no extra issues.

 

[Garage Rat]

Wow lots of input. In my opinion all are pretty much correct. Carbs are great, cheaper and really call to the mechanic in us (i.e. see post about carrying Carb Kit Float, etc.). I prefer EFI and instead of a carb kit I carry my cell with a hook up to the EFI, same thing different day

Anyway, EFI is clearly better if you don't want to mess with it once you have it set up. A carb needs to be cared for each season, and EFI not so much. Since there is allot of information already posted that is excellent, I won't add much, I'll just tell you my experiences with adding EFI as I've done it a bunch. First the units "DO SELF LEARN"! However, if you want to get the ultimate, for example if you frequently going down the 1/4 mile, then fine tuning above an beyond the self learning is recommended, though u don't have to. Most self learning curves will run richer to protect the engine and leaning it out and tweaking the curve will give u a bit more HP.

I have installed both FiTech and Sniper units, never done FAST. The Sniper has far more fine tuning options and allows for more systems to be hooked up and tuned. It's also a bit more difficult to install, just go to the websites and check the instructions for each.

As you're putting this on a 318 from an original 2 bbl, I'm guessing your not worrying about that last bit of HP and just want a good reliable EFI system. IF that is the case I would recommend the FiTech, its a snap to install and the self learning gets the vehicle running really well, again with the caveat previously discussed. You will still need the basics as others, who clearly know what they are talking about have said, O2 sensor, proper feed and return lines, etc.

Good luck with your project.

 

[Garage Rat]

Does EFI add some complexity? Of course it does. But at least my FAST EFI system (and I suspect all the others) use standard, typically GM, modules. So if one goes bad, you probably have a better chance of getting that module at Napa than you do an Edelbrock carb gasket!

So the reliability of EFI systems does not worry me.

After I installed my FAST EFI system I drove my Road Runner across country. My 383 Road Runner achieved an overall average of 17.2 MPG over 5,800 miles for the trip. Overall meaning not just highway miles, but ALL driving for the whole trip. In addition, I discovered I had a fuel vent issue so I was pissing a gallon or two of fuel out the vent when I filled it up, so my actual mileage was probably better. And we didn't drive like granny either. That's pretty darn good fuel economy if you ask me.

Like anything in life, there are pros and cons. Carbs and a EFI systems have their own set of pros and cons. Both systems, properly set up, can work really well. Both systems, poorly installed or setup, can run like crap. And neither system can miraculously take an engine in poor condition and make it run well. So think through all the pros and cons and make your mind up as you choose. There is not one right answer.
(By the way, I am going to do another trip across country and this will be with a carbureted 73 Road Runner, so I have both types, and use both types. )

Well Said!

 

[Bob Benson]

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

Only know one person who went thru the 2bbl to 4bbl 1406 edelbrock on a 318, loved it. Decided to do the fuel injection thing, Holley, ran it for about 4 months, took it off and went back to the 1406. He comment was it seemed he could never get it to run right consistently. Know he had a professional tuner person do the work and tuning, but do not know if he 'tinkered' with it or not, just know he went back. I tried one on my 67 Barracuda 273 high performance rebuilt motor and did not like it and went back to an edelbrock and was much happier. Did find the sweet spot in tuning the carb and it staying in tune for months and months, but you gotta work at it. Good luck, cheers

 

[firiepete]

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

My Sniper install has been great. A few bumps along the road. Holley now produce a fuel pump attached to the sender unit. No new tanks etc. Wish this option was available 4 years ago. Don't over think.

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

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

Have a look at this fuel pump. Easy install.
Holley: 12-308

Good luck.

 

[Wietse]

The 12-380 says GM, the Mopar B-body one is 12-384.
https://www.holley.com/products/fue...uel_pumps/muscle_car_efi_modules/parts/12-384

I have one of those pumps installed on my car, easy as it is direct fit to OEM tank.
Since a pressure regulator is integrated in the assembly I only required to run a 3/8" fuel supply hose directly to the Sniper Stealth unit and no return is required.

Do install a 5-10 micron filter in the fuel line after the pump to avoid any drama's with the injectors.

 

[451Mopar]

New performance / race carbs are not inexpensive. One of the least expensive 800+ cfm carbs like the Edelbrock AVS2 is $475.
A Holley Ultra 850 cfm Avenger is $755. Quick Fuel Q-850 is $972.
Before trying the FiTech EFI, I was running a Quick Fuel 4150 flange Q-1050 E-85 carb that was around $1,000 with no modifications or tuning.
I think the Carb, performance low pressure -8 AN fuel system with return type regulator, 250 GPH pump and filter, and tuning parts was actually more expensive the the EFI setup. I was able to run the EFI system with a $60 reman lean burn distributor. I still used the old MSD ignition box, but the EFI has the rev-limiter, 2-step, Wideband O2, Electric fan controller and such included with the EFI. If you add all those functions to your carburetor engine it all adds up really quick, and the wiring is actually more complicated because all the individual boxes are mostly stand-alone and don't integrate easily with each other.

I got nothing against carbs, been running them for 40 years. First Holley 4160 carb I bought around 1980 was a factory re-manufactured one from Super Shops for $59
Now a New 4160 Holley is $609
I think the Reman 600 Holley Street warrior can be had for around $258 which is about as inexpensive I have seen for a factory sold carb.
I have never run one? It might be OK on a stock or mild engine running around sea-level to 1,000 ft altitude.
Here in Colorado, very few carbs run correctly out of the box, and if taking a drive from the front range into the mountains you can easily change altitude several thousand feet. A trip up Pikes peak could be an altitude change of over 10,000 feet in about a 2 hour drive.
Also, summer heat and high altitude will vapor lock many factory type low pressure mechanical fuel pump systems.

I'm just saying it is hard to compare the costs without looking at everything involved. The closer to stock you car is, you may not need or want all the extras that come with EFI. If you have a mechanical radiator fan, then don't need an electric cooling fan controller. If you don't need a rev-limiter or two-step, or power adder control, then you don't need those extras that come in the EFI. If your fine with the carb tune, don't need the O2 sensor / monitor.
Originally I never tuned with an O2 sensor, just street and race track. Problem is it takes a long time. Here it is hard to get 3 or 4 test runs at the track on a test-and-tune day. Tearing a carb gasket while tuning can set you back alot of time unless you carry extras. Accidently dropping a screw, spring or other part can be difficult to find, and hopefully it didn't fall into the carb or intake.
EFI tuning is just quicker and easier. Once the IAC / throttle position is set, most tuning can be done without opening the hood.
Same thing with the ignition timing if the EFI is controlling timing. Changing the ignition mechanical and vacuum advance curve on a normal Mopar distributor, you have to pull the distributor apart and modify the advance slots and springs, and vacuum canister stroke and spring tension. With EFI, it's a few clicks on a keyboard.