To EFI or Not EFI, that, and which one, is the question.

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My only turnoff with EFI swap is the added complexity for diagnosing and repairing them.  Especially true for things like the holley sniper EFI.  There's no such thing as spare parts or OBD2 ports for it.  When they crap out, which they have, be prepared to take the whole unit off and mail it to holley and wait 6 weeks for it to be repaired.

If I were do to an EFI swap, i would lean towards something more OEM.  For the fact that you can plug in a code reader and pull your codes and you can take your butt to autozone or summit racing and buy sensors and injectors for it.  The holley sniper, you are trading simplicity in the initial install for simplicity down the road when its time to do any sort of maintenance.  

I agree on the OEM. That’s what I’m trying to do, it feels like old hot rodding. In 1969, I had a 1962 corvair and I would visit the junkyards of SoCal to find something to make it better. Starting from a Corvair, that wasn’t difficult. I wanted to make my 73 a better car than it was. A newer, more modern engine seemed doable. And since they’re not making many carb car anymore, EFI seemed to be the baseline for better. I wanted to do a newer car than a 87 TBird, but it feels like a good learning project. I’m glad I went this way, but I’m still months away from knowing.

Well, there is the cleveland manifold base that allows you to bolt on the Ford Racing (I think..) upper FI intake. It allows use of the 5.8 factory fuel injection components, but for a cleveland, you probably still end up going with an aftermarket ecu. 

Plus you have the shock tower braces to deal with.

That's one of the details you never hear about. I recall at the time I installed mine in 2017, that there was not even a mention about this in the install doc.
While they are affordable ( got one from evilbay as Derek VGG would say) and really easy pizzy to install. In fact they should be part of the harnesses of the EFI's that are sold or at least have a connection ready and documented for that. I mean when you pay around $1k for a unit, it's not like the added 10 or 20 that would make a diff.
I'd bet 8 out of 10 installs don't have one.
So, in the Opel community, the recommended thing when installing an electric fuel pump (doesn't matter if you are carbed or swapping to factory or custom FI) is to install an oil pressure switch as well. If the engine stops (or if running an oil cooler/remote filter and you have a catastrophic leak) oil pressure drops and shut-off the fuel pump.

The inertia switch is recommended as well. Having the two should cover most contingencies.

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I installed a Sniper EFI kit this summer on my 71 and have never looked back.  Starts right up, idles perfectly and the vapor lock that I was experiencing is gone.  While I would have loved to keep my 429 completely stock I wasn’t able to drive it which was killing me.  Looking forward to driving my car a lot more next year!

I put a Sniper on mine last year and it has been a little bit of a mixed bag. I will share a couple things I have learnt from the process. 

1: Make sure everything else on your car is good. A carb is a pretty simple tool and wont care if you have an exhaust leak. I finally found my car had a small exhaust leak that likely has been causing me some issues making the sniper think I was lean so in turn it would make it super rich. 

2: Make sure you go through the instructions and follow directions as best as you can. I have never had any RFI problems, but through troubleshooting other things I have seen it with a lot of other people. 

3: Go over the system if your having problems. I thought I was having problems with my tune for a while, and was getting pretty frustrated, when I ended up finding out that it was a bad injector. The shop said Holley uses just cheap Chinese injectors so I ended up replacing them with some Bosch injectors. It had initially been fine, but one day when I was troubleshooting I pulled off the air cleaner and actually looked, and to my surprise one injector wasnt doing anything. And some people have said the Snipers have problems with the injector plug coming off. Mine was the actual injector, but check things over. 

Im sure once I get this dialed in really good it will be awesome, it has just been a bit of a journey. 

I've been debating the same question. I spent almost an entire summer dialing in my pieces/parts (that's another story) 650ish Holley  vacuum secondary carb. I changed idle fuel restrictors, idle and main circuit air bleeds, fuel channel restrictors beyond the normal main jet changes. I learned a ton in the process. I still need to add an electric choke conversion as I have no choke at the moment. It is very cold blooded but the choke will help that. I KNOW this carb inside and out and hesitate to scrap all that effort for a throttle body EFI that may not perform significantly better. Plus, I'm old school and not real savvy with EFI, not that I can't learn it. Sorry for the ramble... 

MKSpeedlab makes some pretty good points here , here is what I would add to that.

When our cars were built, they were pretty simple, with low energy ignition and charging systems, now add a high energy ignition and for good measure lets install a 100 or 150 amp  charging system because we had to have that mega watt sound system and dual electric to cool off that that uber hot new stroker motor.

You have just made the perfect trap for adding some EMI issues when you install that aftermarket throttle body EFI.

 when you upgraded all of your sub systems, did you plan on EMI ? , probably not.

On the EFI units that I have installed, neither did the manufacturers. ( no EMI tape installed or provided with their kits) .

Another issue is  heat, if I were going to install EFI on my ride, I would keep my ECU as far away from EMI and HEAT as possible and NOT mount the ECU on the throttle body ( most don't do this) now let's build this system with the cheapest components   they can find and there WILL be failures.

I have installed some EFI kits on friend's cars, knowing all these things and still had issues. one did go a full season before IAC issues and another ran PERFECT for only a week, customer service was VERY little help and had to send the throttle body in for service (injectors) and the company LOST, yes LOST the throttle body and had to replace the unit, that car is sitting at a (TUNERS) shop (not my idea) since late August.

Looks like really like my carb and aftermarket EFI is not quite what it COULD be just yet.


A carb is a pretty simple tool and wont care if you have an exhaust leak.
That one got me stuck for over a month. Changed the gasket twice, looked for leaks and assumed all was fine. Yet the AFR was going thru the roof, and the engine flooded as a result not a minute after I would start it.
I've found out the problem was the way my headers were fabricated, where the pressed tubes meet the flanges on the inside, where no gasket can make a diff if you have a leak there.

The problem these devices have and also what makes them so cool, is that they fit any engine.
But to do that  you need a broad range, aka wide band sensor. On a specific OEM application, the manufacturers have performed tests already and the tables are in the rom of the comp. The sensors then only covering a smaller range are only helping a bit for the current gas mix, but do not affect the entire spectrum and because they are not "self learning/overwriting the existing tables realtime" and instead "hardcoded", the read only tables are not altered.
That doesn't say OEM is perse better, it's simply designed for a specific engine.

Regarding parts,
Look for instance here on a respected EFI shop, even if you do not need a sensor, open the page bellow and look at the parts option. "select brand". Basically, you can order exact same part with the manufacturer brand (bosh in this case) or pay $50 more if you want to keep the Holley brand. I have seen the same massive diff with their connectors. A single tiny connector (wanted to extend and split to allow both laptop and handheld to be connected) sold $10 a piece vs many pieces for 1/10 of same price at the manufacturer (molex)..
I'm pretty sure the injectors are the same story

Ya, Im hoping this coming year I have all the bugs worked out. 

The other part I will say, is take your time deciding which one you want. In hindsight, I would likely have paid a little more and got the Super Sniper with extra inputs which would be nice for logging. Or I might even have seen if I could have gone for the dominator with the ECU inside the car with a lot more expandability.

Popping on acceleration is a lean backfire, typically caused by inadequate accelerator pump shot or duration. If the choke isn't functioning properly, then that needs to be addressed before anything else can be diagnosed. Sometimes a "mechanic" is not the guy you bring a car that needs to be tuned. 

There's a great carb shop on LI, Allstate Carburetor. Talk to them and see if they can help, or can recommend a shop to get you sorted.
GMTA. Jim heard what carb I had and immediately said I had the wrong carb and detailed exactly what problems I was having. Switched me to an FST and after I had it installed brought it back to him and he set it up for me. Night and day.

GMTA. Jim heard what carb I had and immediately said I had the wrong carb and detailed exactly what problems I was having. Switched me to an FST and after I had it installed brought it back to him and he set it up for me. Night and day.

That's great news!!

I had similar trials on my car.  When I dialed my vacuum advance in the improvement was incredible.  Better power, better idle, no backfiring.  It was incredible.

That was with a Holley 670 Ultra, vacuum secondary, 4 speed.  I had bought a refurbished dizzy and assumed the vacuum advance would be set.  I was incorrect with that assumption!


I have the Edelbrock Pro-Flo 4 installed on my 427 Windsor and so far (500 miles) it has been a dream. When we had "the freeze" here in Texas last year I wanted to see how it would start/run. Perfectly. The ECU is mounted in the cab behind the glove box. Throttle response is incredible and gas mileage is substantially better as well.



been running a edelbrock avs 2 carb now for 4 years with no problems. if you dont know how old carb is, i would replace. if you use car to just cruise in, keep cfm on small side. to many people go too big and cant tune the thing.
yes go to EFI, I've used at least 6 MSD Atomic and they work flawlessly, control timing through MSD or most distributors, require the least amount of wiring by keeping the kit simple and is the easiest to tune. all will have to do an 02 bung and I recommend an in tank efi pump and a return style fuel system but the GM LS style fuel filter/regulator works great and is a 1 pressurized line setup that saves quite a bit of money.
I have the Edelbrock Pro-Flo 4 installed on my 427 Windsor and so far (500 miles) it has been a dream. When we had "the freeze" here in Texas last year I wanted to see how it would start/run. Perfectly. The ECU is mounted in the cab behind the glove box. Throttle response is incredible and gas mileage is substantially better as well.



I have enjoyed the EFI talk, thinking of one for myself. However, I had to comment on this under hood art work. Could you post a pic of the lucky car this rest in? Great work!
So, I swapped the engine, stock '73 oc 351c to '71 cc 351c with mild cam and oil mods w/ blue thunder manifold (+ ~100hp) Hookers (the less expensive painted long tube model) and upgraded from a toploader to (eventually, after a host of problems with the 1st T5) a T5 z-spec. kept the Holley-rebuilt SA670 carb.

No matter how much adjustring, the carb kept popping on acceleration and puffing black soot (only see that when the car is starting to move, I assume it does it at speed but cant see the fine black powder then. I'm told it's from dumping too much fuel) and the electric choke never seemed to work correctly (or the mechanic, who I tend to trust really couldn't get the carb dialed in correctly) Finally, on Wednesday, the car lost power on the parkway, necessitating a tow (thank heaven for Haggerty Driver's club). Turns out choke was jammed shut and the fast idle cam was damaged. He also says the idle adjustment is not working 100% and he thinks there may be internal damage from the small backfires., but it is running well now.

Started thinking about switching to efi (though part of the reason I decided to switch to a muscle car full-time was because I was sick of asking my bmw's ecu "mother may I?" every time I did anything. (Went from 50+ fuses and relays to 7 fuses and 3 relays, and a whole different set of headaches). So, I'm not sure I want to go back to computer controlled engine/fuel, but I am doing my due diligence.

I have read about various issues with the swap, including needing new fuel pump, tank, lines, header issues and needing to swap distributor (I have duraspark now) bringing the cost and frustration factor up there. I am interested in suggestions about whether to swap and if so which manufacturer and model, or if not, whether to stay with the Street Avenger 670 or go to a different carb (I have read a lot of negative comments about the SA carbs0.

Alternatively, if anyone knows a real good carb guy on Long Island, I would welcome the recommendation, and hopefully can get it all sorted out.

Thanks in advance, luckily I always have my horse Chevy to relieve the stress (Mine's the paint on the right)

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I considered EFI years ago then, I had an epiphany IE: I already own 1 fuel injected car from the late 90s and 2 from the 2000s. I realized the nostalgia I have for pumping the gas pedal on a cold start and keeping the experience of driving my Mustang authentic. Then there is the fact that there are just too many computers in our lives as it is.
Best, Ron
I am the worst Mustang owner in the world. I have an Edelbrock E-Street EFI system for my '71 Mach 1, and it's still in the box. One reason is because the Edelbrock Performer 1406 is just running so dang well. Regardless of the ambient temps or how long the car has run or sat, I turn the key, it starts right up - every time! One thing I did was swap out the mechanical pump for a Holley Mighty Mite inline electric pump that I installed near the tank. If the car has sat for any given time (like a few weeks, or months in the current case), I turn it 'On,' listen for the pump to run then slow down (re-prime the line), the hit the gas pedal once and fire it up - catches the first time, every time, and runs like a champ.

I did go the extra step and picked up the Edelbrock 'returnless' high-pressure pump/reservoir kit, so basically all I need to do is swap out the carb, find a place for the reservoir and ECU, then run the wiring and plumbing. I believe it has the inertial switch and safety features included.

EdM: that is a thing of beauty. I'm rebuilding the 304 in my '80 CJ-7, and picked up a Pro-Flow 4 for it. I was tempted to get one for the Mach 1 and transfer the E-Street over to the Jeep (since it came to me with a Performer intake), but unfortunately they're not offering PF4 for the Clevelands. Bummer. The looks absolute AWESOME, my friend!