400 Rebuild and conversion to EFI
 

I am planning on converting over to EFI as part of the 400 rebuild and am leaning towards a Holley Sniper set up. I have a 481733 coded intake manifold that I had intended on reusing; however, I was advised yesterday that EFI doesn't particularly like short dual plane intakes and that I would be better served with a Performer RPM or a single plane such as a Hurricane.

I was hoping to get some input from the experts here and those that have/are running EFI and what your thoughts are on the advise I received.

Thanks for the help!! Lee

With a TBI setup like a sniper, run the manifold that you would run with a carb.

I do have back to back testing on a dual plane and single plane with my FiTech. It being first on an Edelbrock P4B, then on an Edelbrock Torker II.

The system ran fine and confidently on both intakes. The torker II did have slightly better fuel distribution than the dual plane P4B, but that's not saying that the distribution wof the P4B was bad, the single plane was just better.

With the manifold that you want to run, you should run the Sniper quadrajet instead of trying to adapt a square bore throttle body. It's going to work better.

Great insight and exactly the kind of input I was hoping to get back. Thanks you!! Lee

I run a sniper/worked hurricane set-up on my 535ci Formula. Seems to work well

I would pay the extra and get a Terminator, if sticking with Holley. EFI is NOT the part of a project to go tight with the budget - you get what you pay for.

Also integrate the ignition system with it. A Dual-Sync distributor will give the ECU better (quality) and more (quantity) of information on what the motor is doing, which will make the system more effective. Also, by controlling the ignition, the system will run MUCH more smoothly.

I agree with JLM. There are a bunch of performance-guessers who "think" that throttle body efi systems "need" single plane intakes. Then there are people like JLM and myself who have actually tested, and found the truth.

The dyno chart attached shows my dyno testing, comparing a P4B vs a Torker II and a Holley Street Dominator. The motor details are in my signature below. I'm using FAST XFI Sportsman (basically an EZ 2.0 throttle body, but with a more powerful/tunable ECU) system, with ignition control.

I don't necessarily disagree with any of this here, but for casual users that likely won't put in the time to learn the software and get the most out of it, the Holley Terminator is wasted money. The standard Sniper is still good enough that it's going to beat an out of the box carburetor anyhow.

I also don't believe you can get the terminator in a spread bore pattern (as far as I know). I would still opt for an actual spread bore TBI over a square bore with an adapter.

I do agree however that if you're going to EFI of any kind, you're best off going with timing control as well. To the OP, while doing the conversion I'd definitely recommend getting Holley's hyperspark and dual sync distributor and set the system up for timing control. It just gets better at that point.

"I don't necessarily disagree with any of this here, but for casual users that likely won't put in the time to learn the software and get the most out of it, the Holley Terminator is wasted money. The standard Sniper is still good enough that it's going to beat an out of the box carburetor anyhow."

Even if you don't use all the features, the better units SHOULD have faster processing speeds. All the brands seems to keep that data to themselves, so it is hard to get an accurate comparison. Faster ECU = smoother operation.

Personally, I enjoy having the ability to fine tune the system. My first system was an EZ 2.0 - it worked great, but hated how limited I was. My current XFI Sportsman has been perfect, offer all that I need. But I'm now wishing it had more than just 16 columns to the tables :-)

Lee that's interesting that the "junk " street dominator did as well as the torker 2 but 600 more
Rpm? Odd that it made more torque lower? thank you for sharing that

My T2 and Steve Coombs SD worked Holley Street Dominator dyno numbers were identical on my pump gas motor in the 78 TA. Previous 455 roller motor picked up at the track swapping a worked Qjet for a 850 DP on a spread bore adapter by .3 seconds! SO adapter might not be that bad!
The Stealth system and Terminator is what I would opt for as looks like a carb.

My Mopar buddy had been chasing fuel delivery and even thought maybe floated valves on the top end rpm of his 500" Hilborn stack EFI 383 until his dual sync totally crapped out. New one mysteriously solved all of that! Holley brand distributor. Holley HP system and their "dash".

Couple of observations.

I get hundreds of emails and calls to the shop from folks who are NOT happy with their "electric carburetor" conversions and want to go back to a carburetor. The Holley Sniper system tops the list about 8 or even 9 to 1 over FAST or Fitech. The complaints are ALWAYS the same. Most liked or even loved them when first installed, then they took a crap and left them walking. Holley's service is so good they filed a complaint, put the phone down and low and behold UPS was pulling in with the replacement parts! Seriously ALL praised Holley for customer service, but after multiple issues and failures they were DONE with their Sniper system.

I've also noticed that a high percentage of the complaints I get come from folks with manual transmission set-ups. I have no idea why, but I've been keeping track of that deal and it's got to be 3 to 1 if not a bit higher. Perhaps those systems fair better with slower throttle application and smooth gear changes, not sure, but for sure most of the folks not happy with those systems are using them with manual transmissions.

Personally, and this is an educated guess on my part based on my knowledge with FI systems (yes, I've been using FI and custom tuning for decades, but most of that is with OEM set-ups on GM gas/diesel applications combined with Harley Davidson motorcycles using wide ban O2's and custom tuners) is that we are dealing with the same issues the factory did because these are basically electric carburetors and a wet-flow system. To add to that deal most are using a cold intake manifold (blocked or don't have heat crossovers) and heat is ALWAYS your friend with a wet-flow carburetor or TBI style system.

The other problem is that electronics are sensitive to voltage changes and fluctuations. Using a low output alternator down around 37-42 amps as many of these vehicles came with isn't going to make the grade when electronics are involved. Poor grounds are another problem. Many of these 50 something old vehicles have considerable rust no matter what they look like from the outside looking in. One would absolutely and for sure have to have perfect grounds between the frame and chassis, chassis and engine, frame and engine and battery to all of it. Good grounds are NOT always a part of the deal on these older cars neither are the wire sizing to handle higher amp draws as you increase alternator output and electrical load with modern components that require it.

I'm not trying to put a big black cloud over anyones "conversion" to an electric carburetor, just making observations based on what I've seen and am seeing. Personally I wouldn't touch an aftermarket TBI system with 200' pole. IF I decided to make a switch from a carburetor my system would have 8 bungs/injectors in a single plane intake, and FULL control of timing and fuel curves plus self learning.

That's from the FWIW department and a few things to ponder on...........

Holley in recent years has taken a reduce quality and hand out replacements market standpoint. It's better for their bottom line to let some crap ship out and replace it then to make a quality product to begin with.

In regards to operation of these TBI's with a manual transmission, you've got to change the loop rate values. The software makes assumptions about what it's going on in order to get running out of the box. MOST of these things are plopped on top of a 350 chevy backed up with an automatic transmission. The basic parameters are designed around that kind of environment.

When there's a clutch and flywheel behind the engine instead of a big torque converter, the RPMS can drop too far, too quickly during shifts, or clutch in coming to a stop. The engine sucks up the film on the manifold walls as it tries to recover, you lean out and either have a big bog or stall all together. Bumping up the DFCO MAP cut threshhold and dialing back on the loop rate down function is how you tune that out. You simply need to make sure enough fuel is in the system while the clutch is in and there's no load on the engine.

But none of the manuals tell you this. These are marketed as "Self Learning," which is deceptive because they can't learn fast enough, or in big enough swings to overcome this situation. There is some tuning that you need to be able to do in order to get these things right, especially if you've got them on big, or really snappy engines.

I have an unproven and untested theory, that the guys that have trouble with carbs, because they don't take the time to learn how it works and actually tune them, are the same guys that have trouble with TBI EFI systems because they don't take the time to learn how they work or tune them.

Good points made on manual trans set-ups.

When I tuned HD twin cam engines, for example, I would install wide ban 02's and start with a "canned" map very close for the application. The companies selling tuners, like the Power Vision provide scores of maps and in that list somewhere is one that will get you pretty close right out of the gate.

At that point I would ride the bike and data log, and save the results to one of 6 places. Then I'd get the laptop out and custom tune some of the timing/fuel based on prior experience. The cool thing about that deal is that you can save all your tunes including the original and jump back and forth between them in minutes. I found that by custom tuning overtop of the learned tune I could make improvements in fuel economy and power. On my own bikes I was able to get them up to or near 50 mpg's when they were down in the low 40's before any changes were made. This tells us that relying on electronics and data logging doesn't always produce the best results and that you need to do your homework and get some seat time with your tuner, laptop and the system you have chosen to get the absolute most out of it.......

Yes, this is still true of modern self learning EFI as well.

The way the systems work is to start with a basic table that the software builds based on a few key parameters. Typically engine size, rpms limits, cam size, etc. From the base map that is built off of those customer provided inputs the system then uses the wideband oxygen sensor to modify the VE and spark tables in real time.

The real time inputs are your short term trims. The system is running off it's base map and based on what the oxygen sensor is telling it, it adds or removes fuel in the cells that it's functioning in. Based on what is necessary for the short term trims to create the commanded values from the user, those figures are saved to long term trims which is a modification of the base table.

That's really all that is happening. not rocket science. The problem comes when that base table is so far off of what is being commanded that the short and long term trims are beyond their adjustment windows. For short term trims, that's typically about 30%.

In the case of DFCO and manual transmissions for example, the system may make an assumption that at MAP values of 30kPA and below there is no load and fuel is completely shut off. But what happens on clutch in for upshift and you immediately drop all load from the engine. You may drop to around 25kPa and now the system shuts off your fuel. The engine uses up the fuel film on the intake walls and by the time you're throttle on and letting out of the clutch you're WAY lean and stumble.

The system has no learning values for DFCO, it's a commanded value only. So without knowing that and changing it, you may blame the system as being a pile. That doesn't really make it so, but the idea that you could just put it on the car and everything magically work 100% isn't based in reality.

And you've pretty much got to log that, or have somebody watching the values on the handhelds real time to discover that's an issue,

People that run these systems with manual transmission, I typically tell them to turn DFCO off completed, unless they are willing to log and make changes and absolutely need it for fuel economy reasons.

Thanks Lee. I'm not married to the Holley line, my thoughts were that being the most popular (quantity-wise), the support, not only from Holley, but other users would be greater but I am certainly open to suggestions on another brand. My goal with this build would be around 400 hp, so it looks like the FAST EZ-EFI 1.0 would be the route I would go if I went with FAST. Am I reading you correctly that that would be your recommendation. Thanks--Lee (also Lee here...)

Thanks Cliff. Do you think that the 8 or 9:1 complaint ratio of Holley over FAST and FiTech is the due to a similar ratio of what is being run, in other words, do you think that there are 8 or 9 Holleys to every FAST/FiTech or are Holleys just that more prone to issues? Thanks--Lee

Thanks Jason - At this stage, I would likely fall into the casual user category. Ideally, I'd like to have the flexibility to fine tune it down the road but initially, just plug and play...again, ideally...

The software used in the sniper lineup is a Holley HP light system. It's still plenty powerful though. I really don't think you're going to be missing anything personally.

You asked about complaints from Cliff regarding the sniper line. I think some of the increase in complaints may be sheer volume related, but I don't necessarily subscribe to that as being the only reasons.

I have run several FiTech systems, mine being almost 10 years old at this point. So, I have my biases. Without the FiTech system, the TBI Sniper never gets made. Additionally, FiTech owns the patent for integrated ECU TBI systems, so the primary sniper line-up at minimum is likely paying a royalty fee back to FiTech. That margin hit has to be made up somewhere. I think the basic Sniper line as a result was whipped together as quickly as possible so that the FiTech systems didn't completely decimate Holley's EFI business which had entry level stuff at close to 3x the price of the FiTech.

I believe their product and support has gotten better, but my personal opinion is that Sniper was rushed to market and it's quality as a result of that is/was effected. That is of course my own speculation though. Take it with a grain of salt.

All that said, these things are fairly simple and they all use OEM sensors etc. The biggest issues I see of any of these units, regardless of brand is that it's typically a poor install, or a car that has other issues going on that causes poor performance from these entry level EFI systems.

There are a couple things I tell everyone that is looking that you must do to get the best performance possible.

1. Don't skimp on the fuel system. Stay away from frame mount pumps and under hood reservoir systems. They are all junk. Get a new tank with an in-tank pump and run a proper feed and return line with the system.
2. The car must have it's electrical sorted. The EFI system relies heavily on constant and steady power while also needing to be insulated from electrical interference. If you have a rats nest of wiring in the car, items that don't or barely work, fix that before you attempt to install EFI of any kind.
3. Any vacuum or exhaust leaks need to be cured if present. Vacuum or Exhaust leaks fool the onboard sensors of the units into thinking things are happening that aren't. As a result you either get lean or rich run characteristics that you'll never be able to tune out.

Once you've verified all of the items above, the last thing to make sure you get correct is the install itself. This needs to be clean and methodical without any shortcuts. The biggest one I see is people thinking that clamp on oxygen sensor is good enough for anything other than the trip across town to the exhaust shop to have it welded up. If you cut corners on the install, you'll have a poor experience.

Regardless of the brand you choose, the above accounts for a solid 90% of all problems. Yes some make it out of the factory with issues, but it's not as many as you'd think.

For me personally, I still think the Sniper Quadrajet is what I'd put on your car the way you want to run it. Unless you decide to use a square bore manifold in which case I'd probably recommend the FiTech Go EFI 4.

"Thanks Cliff. Do you think that the 8 or 9:1 complaint ratio of Holley over FAST and FiTech is the due to a similar ratio of what is being run, in other words, do you think that there are 8 or 9 Holleys to every FAST/FiTech or are Holleys just that more prone to issues? Thanks--Lee"

Good question and I really don't know and hate guessing.

I will say that most of the complaints I've had here were from folks who simply had too many failures, not dumping that system because they didn't like the way it worked......

Sometimes with some of this stuff I feel its like asking the dude who works at the "Lost Baggage" counter at the airport, "Hey, how often does luggage get lost?" and he responds, "Every day."

Its not that the information is incorrect, its just that its skewed. People who work in the business of fixing automotive issues, shockingly, hear about the problems. I work in process improvement myself, so I sympathize. I really only ever hear about my company's problems. If it runs like a Swiss watch, nobody tells me about it.

I also have noted that the classic car hobby is strangely cyclical in going from hating to defending things. The Ford Duraspark is my favorite example. It had an awful reputation, Never-Spark etc. But years later go on any Ford forum and people will tell anyone who will listen to, "Just put a Duraspark on it" I don't say that to bash Ford ignitions, but to make the point that peoples memories are short. Everyone will line up to talk about how a Holley TBI, or MSD box stranded someone, as if a carburetor has never ran bad ever or factory type electronic ignition has never ever required a tow truck.


I have a car with a Qjet, a car with a Terminator X, and a car with a big Holley. So Im not biased here or trying to sell anyone on anything. But with this stuff I try to be objective. So just some things to consider.

1. You cant throw a Sniper on a worn out engine with vacuum and exhaust leaks. It will run bad. I really think this is where most people go wrong.
2. If you arent going to use extra features (especially spark control) that the FI systems offers, I really don't think the juice is worth the squeeze. Because they do have more fail points. At a certain point the math wont add up. Just have a nice carb built for your engine and save some money and fuel system hassle.
3. It is an electronic system, its easier to hurt (don't use a 200A jump Box) and its more prone to intermittent issues than a mechanical system would be. Those can be a nightmare to diagnose, I have one in my Terminator that drives me nuts.
4. On the plus side, Its really cool to be able to print your data logs, and fuel maps and have quality experts all over the country help you. Chances are you don't live next door to Cliff or Steve Brule to help you with your carb on short notice.
5. You are going to have a way better idea of how well your car actually runs. I honestly believe that most people's carbs and distributors are not nearly as tip-top as their owner thinks.
6. I wouldn't get too wrapped up in the stranded part. Could it happen, of course. But so could a deer impact. Or a flat tire (How many classic cars have a spare tire?)

A lot of good points in here.
You can either worry yourself to death or just roll with it. With most everyone converting to electronic ignition over the past 40+ years I don't view electronic carbs any different. If people want it they are going to do it.

Like mentioned, failures are always reported on the internet, those that have success you never hear about. So I tend to think the fail rate vs success rate is a bit lopsided.

Myself I have had 2 snipers in service for 4-5 years each now and not a single problem with either. The rest of the cars are still carbureted and I don't mind that at all. Honestly I'm more of a keep it simple guy that dabbles in the scary electronic world once in a while :)

On a more serious note I've been around this stuff working on it for years and like mentioned already most of the issues Ive seen were self inflicted. Usually the engine has its own set of issues to start with and the owner thinks an electronic throttle body is the cure, or the wiring install is sketchy or the person lacks the knowledge to properly set one up and tune it, nasty fuel systems with 60 year old tanks and lines etc...
An actual parts failure? Yeah that happens, but not as frequent as the other things I mentioned.
Pick your brand and dive in.