EFI upgrade for LA motor?

I'm thinking of upgrading to EFI for better driveability and I wanted to get suggestions and hear some real world experiences. I have a 360 cube LA motor, built from a 90's MP short block, with ported 308 heads, a Comp Cam hydraulic lifter cam, Eddy Performer intake, a Demon 725 cfm carb, 3:55 gears, and a TKO 600 5-speed, in a 1970 Dart. I'm looking at EFI because the current setup is really "cold-blooded" though it idles pretty well once it warms up.

Does anyone have a recommendation for a throttle body EFI system that is easy to install? I already have an in-tank EFI capable fuel pump and regulator. Do I need to switch to a single-plane manifold, or perhaps a carb spacer on the dual plane? Any and all input is appreciated!

I have a Sniper on a small block chevy that is great. Just gotta be real diligent with all your wiring, fuel, grounds and charging system. No hackage or you'll be endlessly frustrated. My '55 starts in zero degree weather with a turn of the key like a new Kia. No touching the throttle or staying there while it warms up. I run a performer rpm intake with a phenolic carb spacer. It helps the IAC as well as keep heat out of the unit. I'm also running the Hyperspark ignition so it's all controlled by the computer.

Definitely stay with Holley for your first system. They have way, way more support than any other brand right now. Don't buy a Fitech cause its a few $$ cheaper. Other one is Edelbrock and if they have a small block mopar package it may be worth a shot as their kits are individual injectors with a new intake. That is the best style but expensive from Holley to go that route.


https://imgur.com/joTipGf

Another vote for a Sniper. If you already have a fuel system it's a no brainer. Get the distributor and ignition to control timing as well.

I believe that our own ThumperDart can put you together a carb that would rival the retro-fit throttle body systems in driveability and for a lot less money and hassle.

For that matter, if your cam is mild and idle not too lumpy, the new Street Demons that look similar to the old Thermoquads are very good carbs right out of the box for mild engines. And for $300 or so, are a real bargain to boot. Lots of Youtube videos on them.

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Just gotta be real diligent with all your wiring, fuel, grounds and charging system. No hackage or you'll be endlessly frustrated.

THIS IS FACT

Thanks for the input. Are you running an open spacer? How tall is it?

I didn't put this in my original post but I drive the car spring/summer/fall here in Idaho, so temperatures from about 45 degrees to 100 degrees, and I drive in elevations ranging from 800-5200 feet above sea level. No disrespect intended, but do you honestly think any carb can handle those conditions as well as an EFI system with it's multitude of sensors?

The Holley Sniper is probably the best deal for you. There are various models and different price points. I'd probably go with a Stealth version but they are a little bit more expensive. The Stealth has the same basic size and shape as a Holley double pumper so your existing throttle linkage should hook up okay. I highly recommend that you download the instructions from the Holley website before you buy anything. There are a lot of details that you have to work thru with the wiring and fuel plumbing so do your homework up front rather than later.

I've installed a bunch of Snipers over the past several years. Most of them work great right out of the box but sometimes they do have a problem so make sure you buy from Summit and keep all of your packaging and documentation so you can return it easily if there is an issue.

A Sniper system will work a lot better than a carb once the Sniper is properly dialed in. It does take some computer skill to dial a Sniper in so you need to think about that. Ideally you need a Windows laptop to really understand and work with a Sniper. You'll also need the matching Hyperspark distributor to control the ignition timing. The Sniper has a built in data logging system that keeps track of what the engine is doing. A data logger is a great tool to have once you get used to it and learn how to use it.

Thanks for both your replies. I am planning to get the Hyperspark distributor to go with it, and fortunately I have a Window's laptop. I have basic computer skills, but luckily my son is a computer science major and loves cars, so I should be good to go there. I was thinking about going with the basic system because it has the built in regulator and saves a few bucks. I do have an adjustable Aeromotive regulator already installed and was thinking I could clean up the engine compartment a bit by using the built-in. I'm not too concerned on the linkage as I've changed it half a dozen times as I've gone from AVS to Holley to Demon and from AT to the TKO-600. Do you feel strongly that there are other advantages to the 4150-type unit?

Also, do you know if the stock Mopar alternator will supply sufficient amps? I think my unit is rated at 55-60 amps, and all my lights are LED except the headlights and front turn signals. I have a 35 watt stereo, heater and OEM A/C with a Sanden compressor. I'm currently running the MP labeled MSD 6A box with the MP replacement distributor that was made by Mallory.

I’m running a 2” open phenolic spacer as I have the room. Any is better than none and phenolic helps protect the ecu from all the heat transfer.

You can use the built in regulator but its not the most reliable. I’m running a corvette style filter/regulator from Speedway that has -6an fittings. This allows you to put the regulator back on the frame rail and deadhead to the motor. I do have a reusable pre-filter before this regulator as well.

EFI really prefers a modern alternator which is one reason why I designed a swap kit to put the Denso 60 amp unit on a big block or small block. You can try your existing alternator but if you run into issues with electrical noise then you'll need to upgrade to a modern alternator.

The cleanest fuel system is to use a EFI module with the pump and regulator inside the tank. Holley sells a EFI module that drops into a '70 Dart tank. https://www.holley.com/products/fue...umps/muscle_car_efi_modules/parts/12-319
If you don't want to replace the parts you already have then you can use your existing pump and regulator or you can buy the Sniper with a built in regulator. The built in regulators are a known issue so if you go that way buy a spare and make sure you have the correct hex key in your tool box to change the regulator. It takes a weird metric hex key and the screws are locktited into the throttle body so it can be a pain to deal with.

The Hyperspark distributor will work with your existing MSD ignition box and coil so you don't need to change anything there.

I think I'll just go ahead and upgrade the alternator. I actually already have your bracket kit, I just never got around to installing it. Based on everything you said, I think I should go with the 4150 style Sniper and use the external regulator and my existing pump. I did the in-tank probably 7 or 8 years ago and can't remember the brand right this moment, but it was a good one in a brand new tank, and it has been trouble free since, though I've had it regulated down to feed the carb.

Yah, no reason to change out the parts if they are working. The new stuff is more advanced and less expensive but since you already have parts might as well use them. You can probably clean up the plumbing a little bit by moving the regulator. I'd put it on the return side of the system rather than on the pressure side but it should work either way.

Be super careful when you install the Sniper wiring. You have to keep all Sniper wires away from the high voltage plug and coil wires. The Sniper will go crazy if a spark plug wire lays on top of a Sniper wire. You need at least a few inches of air space between Sniper wires and any spark plug wires. You'll also need high quality resistance wires and resistor plugs. I use Firecore 50 plug wires on all of my installs.

The Super Sniper has a few more bells and whistles. I'm sure there's a comparison online. Like I believe you can add sensors on the Super like fuel pressure to have that on the display. The regular Sniper doesn't have additional inputs available. That's probably the only missing item that bugs me. Might be worth comparing the two just to make sure.

I put on a Fitech system several years ago and its been great.
Is that now out of favor?

The temp swing is no big deal. Properly tuned, carbs have been handling it forever. The ThumperDart tuned Dominator on my Hemi does it just fine and that is with no choke. Others will have to weigh in on the current situation with elevations. It has been 50 years since I have been in a car going over the continental divide. But back then, the Fury had a /6 and did just fine.

There are a few advantages to retrofit fuel injection. But only a few. And only the user can determine if those few advantages are worth the extra cost and complexity. Most potential EFI purchasers are exaggerating the advantages of EFI because they are comparing the EFI to an un-tuned or faulty carb. Factory designed and installed fuel injection on modern cars is an entirely different animal and none of us would want to go back to the good old days of carbureted engines. But wet manifold throttle body retrofit EFI is just about as obsolete as carbs are. They are just more expensive, complicated, and with a steeper learning curve for most users.

I will say it again, a properly tuned carburetor can deliver as nearly perfect a driving experience as most retrofit EFI systems can. But I will add this; if the additional cost, complexity, and learning/tuning curve are not a problem, then there is no reason not to go with EFI. Other than the issue of future obsolescence and difficulty in getting certain proprietary replacement parts.

Years ago, decades actually, I put Holley's Projection 2D on my Diplomat. Good luck getting those proprietary parts for it.

Something to consider actually. I can get part for my 51's B&B carb easier.

I am assuming there are headers on the engine. Those with EFI experience, are your typical headers sealed well enough for adding an O2 sensor? Or are we also talking header upgrade to a premium header with O2 bungs already installed?

I have a FiTech also. I have the Fuel Command Center under hood, and I guess those can be a bit problematic (the pump) exposed to heat. I went through two. It seems to be fine now though. I've protected it a bit with some heat wrap also. Mine is on my '89 Diplomat AHB and finding another gas tank that I could use a pump in wasn't working so that's why I have FCC. I'd prefer the sumped fuel pump instead to eliminate heat issues with FCC.

Most headers should be fine for EFI. Race headers with slip tubes are a problem but street headers should be okay. The O2 bungs can go in the head pipes rather than in the collector. The harness from the Sniper should be long enough to reach down to the head pipes.

[quote=DaveRS23][quote=MadMatt][quote=DaveRS23
Most potential EFI purchasers are exaggerating the advantages of EFI because they are comparing the EFI to an un-tuned or faulty carb.

I will say I can tune a carb well and the car ran great prior to the EFI but there is a noticeable improvement in idle quality and power around town. Would it make more power on the dyno. Not that car I care to dyno but keeps the plugs alot nicer from early spring, thru hot summer and back to cool weather.

It's definitely not a good choice for those that have carb problems. You need to be good at problem solving before slapping on the Sniper or you'll be cursing Holley and it's really not their fault. Some should stick to driving their daily toyota. I hear it all the time on facebook..


EDIT: This was not directed at the OP in any way.

Thanks again for all the info and input, I REALLY appreciate it! One more question, have you installed these systems on dual plane manifolds and have you had any issues? Do you think a carb spacer is needed on a dual plane?

I hear what you're saying, and I agree. I think I do a decent job of tuning a carb, and I also had the carb tuned on a chassis dyno several years back. It makes good power and torque, no problem starting it, and it idles pretty well once it warms up and has terrific throttle response. But I think it can be better with EFI, especially in the variety of weather and elevations it sees. It seems overly sensitive to changes in the ambient temperature, getting "fat" when the weather is hot and occasionally dieseling when I shut it off. I've upgraded the brakes, suspension, A/C, and transmission to modern standards, so I can't see why I shouldn't do the same for fuel delivery.

I've run the Sniper on a dual plane intake. It works just fine on a dual plane but it might work better with a small open spacer. There isn't a big difference between fuel/air flow with a throttle body and a carb. In both cases you have a mixture of air and fuel flowing out of the base and into the manifold. So whatever works with a carb tends to work with a throttle body.

As far as your other point on EFI performance you are correct, EFI will work much better in terms of automatically adjusting the air fuel mixture for different altitudes and weather conditions. Throttle body EFI will not make more power than a good carb but it should provide better driveability, especially if you add a Hyperspark distributor and use the full computer controlled timing feature.

The data logger is a huge advantage which most people never even talk about. Once you learn how to use the data logger you'll be able to solve all sorts of issues that have nothing to do with the EFI system. A super Sniper with the extra inputs can be used as a simple general purpose data logger. I use mine to monitor oil pressure, fuel pressure and crank case pressure. You can also monitor pressure in the cooling system or brake pressure or line pressure in an automatic transmission.

I wish i had sprung for the Super Sniper for the reasons Andy mentioned. Definitely some added benefits. Certainly not required though. The small open spacer helps the IAC motor in the back. The port ends up right above the divider I believe so getting it some space helps. Some have mentioned a "whistling" when installing directly on top of a dual plane. As I mentioned, I think even a 1/2" phenolic spacer would solve that problem if you can run one. If not and you have the intake off, trimming the divider down some would help I'm sure.

I'm excited at the idea of having the computer control the timing. I know that with a computer you can run curves that would never be possible with "physical" advance. Can you offer any sort of insight into what sort of curves you have used or how you go about selecting a curve? If I remember correctly, I am currently running 34 degrees total advance with it all in by 2400 rpm. My Dart is light (about 3100 lbs) and with the 3:55 gears and the 2.87 first gear in the TKO knock is pretty much a non-issue with premium gas.

I'm putting a Sniper on my 69 340 Cuda. I checked with Holley and a dual plane is OK as long as you cut down the centre divider if present.
This is an Edelbrock Performer RPM manifold (7176) showing how I cut down the divider.

It really depends on the cam. The bigger the cam then the more timing you put into the engine at idle. The nice thing about a Sniper setup is that you can change the ignition curve with just a few keystrokes. You don't have to take a distributor apart and play with weights or springs. If 34 total is working for you then just try some different numbers for idle and then smooth out the slope between those points. I'd suggest something around 40 to 45 degrees of timing for cruising down the freeway.

You can test all of this in the car by hooking up the laptop and going for a drive. Drive down the freeway at cruise and have someone change the timing numbers as you drive and see how the engine feels. Typically you can dial in the cruise timing in just a few miles of driving. Then find a long hill to drive up and make sure that it doesn't ping or knock and you should be good to go.

That's the same manifold I have. How did you make the cut?

Took it to my friend down the street who has a Bridgeport milling machine!!!!

That's definitely the best way to do it!