Considering Holley sniper EFI for my 1969 340. Thoughts from people who have that set up?

harrisonm · 2024-11-27T09:55:31-0600

I know that over the years I have said I would not switch over to EFI on my Barracuda because it ran fine on a carburetor. I think I am about ready to make the switch. I am getting tired of having to crank my car until gas gets up to the carburetor if I have not run it for a week or so. I’m also kind of getting tired of fiddling with the carburetor. It seems like every once in a while it wants to be adjusted, or the choke wants to be fiddled with. I am interested in hearing from people who have the Holley Sniper on their car to see how they like it, and if they have been any problems. Prefer hearing specifically on a 340, but I guess any inputs would be helpful. I guess the base unit now is the Sniper 2, so comments from people with a Sniper 2 would be especially helpful, but any Sniper comments would be appreciated. I currently have a complete MSD set up to include their distributor. I really want to keep that.

jbc426 · 2024-11-27T10:23:45-0600

Sell the MSD and grab the latest version of the Holley Sniper. AndyF & Fastman EFI are the experts on these set-ups, and both are on this forum. They forgot more than most know about the Holley Sniper systems.

rmchrgr · 2024-11-27T10:43:19-0600

I always say this but it makes little sense to run the Holley EFI without the Hyperspark ignition system. Being able to control the timing through the ECU software is a major benefit of the conversion to EFI. Without the timing control you will be leaving performance and drivability on the table. If you are dead set on sticking with your MSD ignition I wouldn’t even bother with the expense or hassle of the EFI, just stay with a carb.

How is the wiring in the car? Another thing I always suggest is to re-wire the car before trying to install any EFI system. You need clean power and want to avoid creating wiring situations that will increase the chances of EMI causing problems. That will definitely happen if the wiring is a mess. EMI (or RFI) will cause no end of frustration since it really has nothing to do with what the program does except that it causes it to not work right.

Don’t skimp in the fuel system either. An in-tank pump is the way to go. Also I’d sat ditch any rubber hose and worm clamps and get -AN fittings for the connections. Don’t want leaks at 60psi.

And last - consider how involved you want to get with the tune. A lot of guys won’t touch a lap top but that’s really how to get the most out of the system. Building custom fuel and ignition tables in the software goes a long way in understanding how it all works. The initial “wizard” tune is generic and is really only there to get the car started. It takes some time to figure out what the car needs.

It really does not matter what size engine you have. Eventually the program will adapt to your driving style. I had a Sniper on a mostly stock 383 for thousands of miles and there were no issues.

Again, if you think you’re just going to plug it in over a weekend and suddenly the car will run perfect don’t waste your time. Invest in all the right components and be willing put the time into the tuning process and you will get some to ing out of it. GI GO as they say.

NC Engine Builder · 2024-11-27T11:16:46-0600

You will spend a BUNCH more time fiddling with, and learning to tune ANY aftermarket EFI system.

LO23M8B · 2024-11-27T11:17:25-0600

They work great.

rmchrgr · 2024-11-27T12:00:03-0600

NC Engine Builder said:
You will spend a BUNCH more time fiddling with, and learning to tune ANY aftermarket EFI system.

I agree that initially there is a big time investment but that will diminish quickly if the user takes an active role in the tuning process. The tuning concepts are the same as they would be with a carbureted engine they’re just presented in a different format.

That said, if you’re not computer literate or are not comfortable tuning with a laptop then it may not be worth the aggravation. It’s not hard software to learn but it does require basic computer aptitude. If you can navigate file folders, fill in fields and perform basic file functions like ‘save as’ then you’ll be fine. If you can’t handle that stuff in 2024 then just throw in the towel and go back under your rock.

For me, having the tuning parameters laid out as a graphical representation actually made the process easier since there is no guessing. Each cell in a table or point in a data log trace has a value. What that means is that it either ‘is or it isn’t.’ Not so much when dealing with mechanical parts.

The software also gives the user much more finite control over the tuning parameters. Maybe you have a flat spot during acceleration and one or two points on an ignition or fuel curve are out of whack. You can change the values for those cells but leave the rest of the curve alone so there’s no residual affect on any other points. That in itself overcomes the stack up of tolerances when dealing with mechanical devices.

Again, yes, there is a time investment but that should be understood. My Dodge never ran better with the Sniper and even got better mileage. 100% win and worth the time.

AndyF · 2024-11-27T12:13:05-0600

Start with the fuel system. Check to see if you can buy a complete EFI tank with build in fuel pump for your make and model. If you have a late model Barracuda you shouldn't have any issues, the early ones might be a problem.
I wouldn't buy a Sniper until you know that you can buy a tank with an internal pump.
The Sniper will work best if it is paired up with a Hyperspark distributor and a CD box.

jbc426 · 2024-11-27T12:34:33-0600

There are several ways to skin a cat when it comes to fuel systems. I used a surge tank system, which has some significant benefits not the least of which is providing virtually air free fuel delivery at very low fuel levels even as low as a gallon or two under spirited road course driving.

The tank pump circulates a high volume of fuel at near "0" psi up to and back from the surge tank to the fuel tank. I silver soldered in a like-sized return line to the sending unit, sourced the electric pump 12V pass-though and the surge tank from Radium Engineering.

The surge tank circulates the fuel through the fuel rails and back to the surge tank through a pressure regulator. Any air trapped in either circuit is purged back to the main fuel tank via the main fuel return line.