TBI upgrade

[skipjack99]

I have a 71 Cuda with a 383 that I am going to rebuild and plan on upgrading the fuel system to TBI, any thoughts on which systems are any good or ones to avoid?

 

[rmchrgr]

Holley Sniper or Terminator X, wouldn't consider anything else. I'm on my 3rd Holley EFI conversion with my Challenger. There's a huge online community for support and tons of aftermarket accessories out there now to expand it's functionality. Holley just recently rolled out a Bluetooth module too. Terminator X has more options within the ECU (it's also a separate box from the throttle body itself) but you my not need that level of capability. Sniper 2 has a Power Distribution module thing now which makes wiring connections easy. If you have decent mechanical and wiring skills it's fairly easy to install with the Sniper being the easiest.

You should also be comfortable with using a laptop and software in the car - things like navigating through screens, saving and retrieving files, filling in blank fields, right-clicking options, etc. If you can't do that kind of stuff in 2025 'cause "you're not a computer person", are scared of or don't trust them, forget it and stay with a carb.

That said, the tuning ideas are the same as a carburetor and mechanical distributor but they are represented and ultimately manipulated through programming. Holley does provide little 3.5 screens to monitor things but they are borderline useless when it comes to making tuning changes. A laptop will be your friend.

It's also important to be aware of the fact that a lot of buyers get roped in by the advertising and hype. I've seen it first hand and it never ends well. If you think it's just a couple easy hours in the garage and the car will run perfectly without ever having to lift a finger, save your money and stick with a carburetor. Do your research, there's more to it than meets the eye.

Here's a few things to keep in mind before pulling the trigger. Be honest with yourself here.

• It's not magic so be willing to put the time and effort into tuning the thing beyond the initial install. Garbage in, garbage out.
• It is a significant investment of money and time which will seem way worse if you end up yanking it out in frustration.
• Buy the whole package as it's designed to work that way - ECU, ignition box/distributor, in-tank fuel pump, etc. That means don't cheap out on certain components (especially the ignition) as you will never achieve the full potential of the system.
• If you're starting from scratch, it's best to have all new (modern!) wiring and have a good grasp of how Chrysler electrical systems function. Mopar is a little different than the Brand-X stuff which can present unique issues to get around.
• If you half-ass stuff (especially the wiring) you WILL have problems. Do things right (which may include critical thinking and/or creativity) and take pride in your craftsmanship.

Hope that helps.

 

[Deathproofcuda]

@rmchrgr

Nice detailed and well balanced response.

 

[rmchrgr]

@rmchrgr

Nice detailed and well balanced response.

Thank you.

For whatever reason, I tend to respond a lot of EFI questions on forums. It's probably because there's still a lot of misconceptions about it and it's fun to dispel myths. I've done a few of them and know what it takes to make them work. I am in no way an expert and have a lot to learn myself but I enjoy that aspect of it. I'm a believer in these systems but not a crusader. I'm not going to get wound up about what's better. Carburetors will always have their place and EFI is not for everyone.

The advertising does make it seem like the greatest thing since sliced bread but the reality is these things come with certain caveats that can easily make you want to blow up your car. Plus, people are stubborn about what they think they know and often tend to mistrust or bad mouth things they don't know or understand. Such is life.

Again, I've witnessed that kind of uninformed buyer scenario first-hand with a neighbor of mine so it's not hyperbole. This guy saw that I put a Sniper on my old '68 Coronet and decided he wanted it for his Brand-X big block cruiser. Problem was, he was not the right type of guy to do it since he is not particularly hands-on. He'd had cars for years but he was not the guy to be bent over the fender every Saturday afternoon. His car also needed a lot of work before it was wise to even consider an EFI conversion. There's often unexpected costs involved beyond the initial EFI package purchase especially if your car is still original or ratty or both. Again, garbage in, garbage out. EFI can't fix intake or exhaust leaks, gummed up valves, incorrect timing or what have you.

One day soon after I go over to his place to look at his ride and tell him what I thought. Above all, the wiring was beyond shot. All the textbook maladies were there. The main battery cable was literally hanging on by one strand of copper, not to mention twist'n'tape situations and random quick splices everywhere for god knows what. Compounding that was the fact he had no idea how bad it actually was. It was surprising that the car hadn't burned to the ground.

I suggested he re-wire the car or at least re-do the obviously butchered parts of it and he looked at me and said why? I'm not sure if he could see it my face but I was pretty much dumbfounded. Despite that glaring red flag, I offered to help him do it. Of course "he knew what he was doing" though so I said OK and left. You can tell where this is going.

After that I didn't hear from this dude for a while. As you'd expect, he ignored my suggestions and went ahead with the install on his own. Needless to say, the car wouldn't start and he called me up asking for help. I made a few general suggestions over the phone and agreed to stop by and give it a look knowing it was going to be an indecipherable mess. I went but didn't do or say much since I had no idea what he did or didn't do except for being fairly certain he didn't read the instructions at all.

He kept messing with it for a while with no luck. After a few weeks of aggravation, he called me again and said was yanking the whole thing. I talked him down out of the tree and told him not to give up. After many hours on the phone with Holley tech support he finally got it running but unfortunately that's as far as it went.

I know for a fact the guy never got involved with tuning it either. After he had it running, I offered to "give him a known good tune" and would walk him through the process of loading it into the ECU. One day he dropped his SD card off on his way to somewhere else so it surely wasn't happening then. Regardless, it was pretty clear that he had zero interest in learning how to load the tune and was essentially expecting me to do it for him. He said he'd come by soon but never did.

A few months later I found out through another neighbor he moved out of town. That was in 2023. Out of the blue a few months ago I got a call from him asking for the card thing back. It had been almost two years after he dropped it off the first time. He came by and I gave him the card but haven't heard from him since. Frankly this guy should have saved himself all the aggravation and hassle and just stuck with his carburetor but I suspect he had no clue how to tune that either.

The point here is to go into this stuff with your eyes open and be realistic on how involved you want to get with it. They're great if you put the time into them but are an expensive clusterf*ck if you don't. They are not going to fix a poor running engine so put the time into optimizing what you have already and then decide if it's worth doing.

 

[MoparCarGuy]

I wholeheartedly agree with everything that @rmchrgr posted. This is not for the faint-of-heart and should only be done on a car that is fully-sorted out.
The Holley Sniper systems can do almost anything you want but I would not buy a system with the ECU in the throttle body. The Terminator X Stealth system, as noted by @rmchrgr has a separate ECU which can be installed in the interior of the car. The harness is long enough to locate your ECU and the Hyperspark 2 ignition box inside the car. I installed my ECU under the driver side dash under the cowl area and the ignition box on the lower firewall at the center of the transmission tunnel. Here is a good article from 2017 on the Terminator X Stealth system.

Here are few of the things that must be reworked to properly do an EFI conversion. Some were mentioned by @rmchrgr but I will just list my thoughts to cover the bases.

Research - Study everything you can to learn about EFI so you do not make the mistakes others have made the hard and costly way. EFI Systems Pro is a great resource and has unbelievable tech support both before and after an installation. The Holley forums are also invaluable.
Fuel System - Holley regulator with an EFI fuel tank, in-tank pump, fuel filter, and a full return line to the tank (do not cheap out with an inline pump and no return). This thread has some good info on fuel filtration and fuel system.
Electrical System - Upgrade to at least a 100-Amp alternator (Powermaster one-wire with internal regulator) and the Holley power module (these are a newer development and solve lots of power issues). All wiring should be properly thought out and routed accordingly. Buy the proper size loom coverings and make it look professional. You need to get this done properly the first time around as you will never make time to redo it.
Time - The installation is NOT a "let's do it this weekend" project. It can be done but I would take as much time as necessary to get this right. The last thing you want to do is install everything and then spend an inordinate amount of time troubleshooting why it would not start or has other issues, e.g. radio frequency interference to your sensor inputs, etc.

There is so much to research and consider so good luck if you choose to take this on. Remember, if it was easy, then anyone could do it.