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

[Fabrice]

if of any help, found back some picts.

That's where I did the holes (feed and return lines)


here once installed


I have an adaptor that is secure on the apron, and the lines are bolts on both sides, so no wear possible
I did this because the pre filter, the pump could not have been in perfect line with the post filter added in the rear, so it's now as on right side.
A solid cover was also added to it.

edit: couldn't find picts,
so as there was still day light...

 

[tpj71mach]

if of any help, found back some picts.

That's where I did the holes (feed and return lines)
View attachment 64567

here once installed
View attachment 64568

I have an adaptor that is secure on the apron, and the lines are bolts on both sides, so no wear possible
I did this because the pre filter, the pump could not have been in perfect line with the post filter added in the rear, so it's now as on right side.
A solid cover was also added to it.

edit: couldn't find picts,
so as there was still day light...

View attachment 64570

View attachment 64569

Thanks for the pics, nice job! That is just where I was planning on going in to the engine compartment and feeding the lines to the back of the Sniper.

 

[Fabrice]

@tpj71mach no prob, that's what we do on here
This is the safest way I could find. I did also spend some time to secure/box the fuel pump (external one) and I was able to connect the pre filter without loop that you otherwise would get to satisfy all the angles/curves that you need to follow. Not to mention, I can drop my tank just as it was in original situation as nothing aside the sending unit hose is in the way for that. Not that you do that everyday, but as usual, it's when it's hard to reach that our babies decide to get hill right there
Robsweden, went the passenger side for that reason. I opted to relocate the post filter to the front.
I thought about reusing existing holes, but the nearest was too low, and the curve on that location on the apron gives you the angle that you want and the lines are not too long and it's easy to access the fittings.
Good luck!

 

[rmowrey]

I've been running a Holley Sniper on my '73 with a 351C, for 4 years now. Runs fantastic! EFISystems Pro and Holley have great customer support, and MadScienceMotorsports.com can do custom tunes by email.
I used the factory 3/8" hard line from the trunk to the engine compartment. I used a Holley returnless intank pump so I didn't have plumb a return. You just cap the return line on the sniper.

 

[tpj71mach]

I've been running a Holley Sniper on my '73 with a 351C, for 4 years now. Runs fantastic! EFISystems Pro and Holley have great customer support, and MadScienceMotorsports.com can do custom tunes by email.
I used the factory 3/8" hard line from the trunk to the engine compartment. I used a Holley returnless intank pump so I didn't have plumb a return. You just cap the return line on the sniper.

I wasn't aware that running without a return was an option, good to know, thank you

 

[Fabrice]

@tpj71mach to be clear, there must be one way to ditch the pressure built up. That it's done by a pump assembly or by the regulator on the unit is the same. Indeed if you go for this kind of pumps, that saves 1 line to route. Back in 2017 there was only one Sniper kit, and no accessories.

While hurting your wallet a tad more. there are also details that are welcome.

- if you are handy with a laptop, you can buy a connector that will fit where the handheld is connected to.
very handy as you then can have your laptop on your seat and datalog realtime, vs run/log, stop. extract the card, insert in pc, pick the logs and repeat.
- the sniper comes with absolutely garbage rubber plugs to close the back ports.
buy a set of nylon high temp plugs and use them vs the cheapo ones that cracks ( left me almost stranded because of that tiny thingy and ruined my config, which I forgot to save...) I have after that seen that on my other unit, still in box for my 429 that the rubber is also degraded.
- Not necessary if you use a pump from holley that is ment to produce the 60 psi exactly. But if you use a third party one, that is with no doubts as good, having a fuel pressure gauge that you can hook at the inlet on the unit is handy, especially if you have issues that could be pressure related.
- make sure you download from their site the latest firmware. Some units were shipped with missing files and some with older firmware.
- register on the holley forum now, as sometimes it takes ages before they allow you to ask something.

For first try, make sure the blades are open a tad, say, turn the screw 1/4 extra from the moment you see the blades opening. As even if you have not set the IAC, TPS or something else not 100% ok, this will give you the chance to start without issues and let it warm up at a may be higher idle than you want, but you won't get issues.
You won't be the first to be overwhelmed when it comes to the first stressy moments.! As you need also to check for leaks, see if nothing on the handheld goes thru the roof. If slightly open, even if IAC is at 0, you are sure it will start right away.

 

[tpj71mach]

@tpj71mach to be clear, there must be one way to ditch the pressure built up. That it's done by a pump assembly or by the regulator on the unit is the same. Indeed if you go for this kind of pumps, that saves 1 line to route. Back in 2017 there was only one Sniper kit, and no accessories.

While hurting your wallet a tad more. there are also details that are welcome.

- if you are handy with a laptop, you can buy a connector that will fit where the handheld is connected to.
very handy as you then can have your laptop on your seat and datalog realtime, vs run/log, stop. extract the card, insert in pc, pick the logs and repeat.
- the sniper comes with absolutely garbage rubber plugs to close the back ports.
buy a set of nylon high temp plugs and use them vs the cheapo ones that cracks ( left me almost stranded because of that tiny thingy and ruined my config, which I forgot to save...) I have after that seen that on my other unit, still in box for my 429 that the rubber is also degraded.
- Not necessary if you use a pump from holley that is ment to produce the 60 psi exactly. But if you use a third party one, that is with no doubts as good, having a fuel pressure gauge that you can hook at the inlet on the unit is handy, especially if you have issues that could be pressure related.
- make sure you download from their site the latest firmware. Some units were shipped with missing files and some with older firmware.
- register on the holley forum now, as sometimes it takes ages before they allow you to ask something.

For first try, make sure the blades are open a tad, say, turn the screw 1/4 extra from the moment you see the blades opening. As even if you have not set the IAC, TPS or something else not 100% ok, this will give you the chance to start without issues and let it warm up at a may be higher idle than you want, but you won't get issues.
You won't be the first to be overwhelmed when it comes to the first stressy moments.! As you need also to check for leaks, see if nothing on the handheld goes thru the roof. If slightly open, even if IAC is at 0, you are sure it will start right away.

Thank you for the guidance, my intention is to run two 3/8 lines front to back along the drivers rocker where the original fuel feed goes. I have already bent the both pipes using the original feed as the template. I planned on using the Aeromotive fuel tank that has the feed and return ports at the factory sender placement so it will look as original as possible. I think I will stay with the plan of running a return into the in tank pump, considering I have already formed the dual pipes and don't wish to back up if not necessary. As I am running a non Holley pump the fuel pressure gauge is a very good idea. I am computer literate but certainly no expert, so that is intimidating. My two sons aged 19 and 22 have been helping me tremendously with this build, as I was in a car accident a year and a half ago and messed up my back so I can't really lift anything. They have assured me that they will handle the computer part. I asked them about the lap top connector and they both thought it was a good idea and we should definitely get that. I will also remeber to change the vacuum plus when I get my unit. Thanks

 

[Hotstang]

Just installed the Holley sniper on a 67 289 mild street build. Used holley's drop on fuel pump/sender and no return line.i also installed holley's sniper distributer which made it easy to set up for initial start. Not a lot of miles so far but will pleased with the ease of install and throttle response

 

[Fabrice]

@tpj71mach no need to worry for the "computer" part.
Holley made it really easy and using the wizard, you're set in matter of secs by simply selecting/ basic options and set a few value like whats the displacement, number of cyls etc...
The 3 most important things for a successful and durable install are to make sure you have a good solid 12v at the column that goes to the coil (red/green wire after the ignition key switch and before the next junction), that you have the O2 sensor air tight (preferably not using the clamps that holley provides but a good old bung that you weld) and that your exhaust has no leaks at the flanges like mine had.

 

[tpj71mach]

Just installed the Holley sniper on a 67 289 mild street build. Used holley's drop on fuel pump/sender and no return line.i also installed holley's sniper distributer which made it easy to set up for initial start. Not a lot of miles so far but will pleased with the ease of install and throttle response

Good to hear, glad it went well for you, here's hoping I can tell the same success story.

 

[tpj71mach]

@tpj71mach no need to worry for the "computer" part.
Holley made it really easy and using the wizard, you're set in matter of secs by simply selecting/ basic options and set a few value like whats the displacement, number of cyls etc...
The 3 most important things for a successful and durable install are to make sure you have a good solid 12v at the column that goes to the coil (red/green wire after the ignition key switch and before the next junction), that you have the O2 sensor air tight (preferably not using the clamps that holley provides but a good old bung that you weld) and that your exhaust has no leaks at the flanges like mine had.

I am hoping it will go well. I definitely plan on welding a bung not using the clamp on, so that should eliminate some risk. I'm planning on welding it in to the down tube as I am using Sanderson block hugger headers.

 

[DShearman]

I have been called an artist due to my carb tuning wisdom. I am also old. LOL.

Ron

Any good resources you can recommend for someone looking to improve their carb tuning skills? I'm happy to sit there and tinker, but any guides or references that lay out the principles to be followed would be a big help.

 

[c9zx]

DShearman, I can recommend"How To Super Tune and Modify Holley Carburetors", by David Visard. Published by SA Design. There is a lot more to it than most people think. Even if it isn't a Holley carb, they all function pretty much the same way even if they look radically different. Good luck with developing your tuning skills. Chuck

 

[Ron Tanzi]

Any good resources you can recommend for someone looking to improve their carb tuning skills? I'm happy to sit there and tinker, but any guides or references that lay out the principles to be followed would be a big help.

I prefer to the "old school" book method. I have a few Holley tuning manuals and a few Carter tuning manuals ( Carter applies to Edelbrock performers/AVS carbs as well). I find that a book is better, as you can just re-read a certain procedure or specification again and again. I also have 30 or so period Motors and original factory manuals for Autolite and Motorcraft carbs . There is a lot to sort through and there is still a lot of reference material out there. I am not being cocky but experience helps.

Ron

 

[DShearman]

Thanks Ron and c9zx. I have a Motorcraft 2100 so will look for manuals specific to that, and check out the "How to" you recommend.

 

[mrgmhale]

I am chiming in a little late in this thread, but once I took the time to read the comments I felt I ought to share my thoughts on the EIF vs non-EFI matter... For what is may be worth.

I feel if a person has a carburetor based fuel system that runs well, starts cold well, performs well, and said person is not driving to places with wildly differing elevations, it is reasonable to keep the carburetor based fuel system. Further, if a person is after outright performance, I have yet to see a Fuel Injected system significantly outperform a non-EFI (carburetor) system when the carburetors are tuned and working properly. A properly set up carburetor system does a great job.

The EFI solutions are something I would recommend for a carburetor based engine pretty much only in the event the car is being taken to areas with extremely significant changes in elevation, as the EFI system will adjust the air/fuel ratio based on its input signals (atmospheric pressure, Oxygen Sensor), whereas to make aid/fuel ration changes in a carburetor will require at least changing the main fuel jet size for the different elevations - which is not practical to do for vehicles going between higher and lower elevations frequently.

If a vehicle's carburetor fuel system is causing problems, moving to an EFI solution is just as effective a solution as identifying the cause of the fuel system problem and correcting it while keeping the carburetors in place. But, if I were planning or needing to go between significantly different elevations I would likely end up getting an EFI solution. Otherwise, it is an expensive was to take care of a situation on a needless manner.

One of the potential downsides to an EFI system is the availability of parts after a few years elapse. Also, if the eFI system develops a problem it may be difficult to find a technician willing to burn the time needed to learn the aftermarket EFI system, much less diagnose and correct the problem. Another problem I have observed is on aftermarket EFI systems where the fuel return line was not set up correctly, much not installed at all. I have also seen some systems in the market that say no return fuel line needed (I wonder how well that has worked out).

Anyway, for me and our 3 vintage mustangs and Shelby GT500 I plan to keep using their carburetor based powertrains. I have better things to get with the money the aftermarket EFI systems cost. That said, I do like the idea of being able to dial in a particular state of tune using a laptop connected to an EFI system. That is way cool, but in my case totally unnecessary. YMMV

 

[Ron Tanzi]

Thanks Ron and c9zx. I have a Motorcraft 2100 so will look for manuals specific to that, and check out the "How to" you recommend.

The 2100 is among the easiest to rebuild. The biggest factor is cleanliness of everything inside the carb and attention to detail but they are simple. On the other hand if you said you had a 4300.......not so much of the simple.

Ron

 

[71ProjectJunk]

I am chiming in a little late in this thread, but once I took the time to read the comments I felt I ought to share my thoughts on the EIF vs non-EFI matter... For what is may be worth.

I feel if a person has a carburetor based fuel system that runs well, starts cold well, performs well, and said person is not driving to places with wildly differing elevations, it is reasonable to keep the carburetor based fuel system. Further, if a person is after outright performance, I have yet to see a Fuel Injected system significantly outperform a non-EFI (carburetor) system when the carburetors are tuned and working properly. A properly set up carburetor system does a great job.

The EFI solutions are something I would recommend for a carburetor based engine pretty much only in the event the car is being taken to areas with extremely significant changes in elevation, as the EFI system will adjust the air/fuel ratio based on its input signals (atmospheric pressure, Oxygen Sensor), whereas to make aid/fuel ration changes in a carburetor will require at least changing the main fuel jet size for the different elevations - which is not practical to do for vehicles going between higher and lower elevations frequently.

If a vehicle's carburetor fuel system is causing problems, moving to an EFI solution is just as effective a solution as identifying the cause of the fuel system problem and correcting it while keeping the carburetors in place. But, if I were planning or needing to go between significantly different elevations I would likely end up getting an EFI solution. Otherwise, it is an expensive was to take care of a situation on a needless manner.

One of the potential downsides to an EFI system is the availability of parts after a few years elapse. Also, if the eFI system develops a problem it may be difficult to find a technician willing to burn the time needed to learn the aftermarket EFI system, much less diagnose and correct the problem. Another problem I have observed is on aftermarket EFI systems where the fuel return line was not set up correctly, much not installed at all. I have also seen some systems in the market that say no return fuel line needed (I wonder how well that has worked out).

Anyway, for me and our 3 vintage mustangs and Shelby GT500 I plan to keep using their carburetor based powertrains. I have better things to get with the money the aftermarket EFI systems cost. That said, I do like the idea of being able to dial in a particular state of tune using a laptop connected to an EFI system. That is way cool, but in my case totally unnecessary. YMMV

Very good points here. I started selling aftermarket EFI kits in the early 90's. None of those early kits have any support anymore. The aftermarket moves on, just like the OEM's do, and they stop supporting their systems after a while, just like the OEM's do. The difference is that usually on an OEM system there were millions upon millions of cars built with those systems, and the aftermarket will support them for decades after the OEM's have stopped supporting them. With the aftermarket EFI systems, when the manufacturer goes onto the next new and best thing, the support and parts just vanish, you are just stuck with an old system with no parts availability and no one that knows how to deal with them or repair them. I remember selling the B&M Superjection and the Halltech F8 in the 90's, try to find any parts or information for that stuff today...

 

[mrgmhale]

Very good points here. I started selling aftermarket EFI kits in the early 90's. None of those early kits have any support anymore. The aftermarket moves on, just like the OEM's do, and they stop supporting their systems after a while, just like the OEM's do. The difference is that usually on an OEM system there were millions upon millions of cars built with those systems, and the aftermarket will support them for decades after the OEM's have stopped supporting them. With the aftermarket EFI systems, when the manufacturer goes onto the next new and best thing, the support and parts just vanish, you are just stuck with an old system with no parts availability and no one that knows how to deal with them or repair them. I remember selling the B&M Superjection and the Halltech F8 in the 90's, try to find any parts or information for that stuff today...

What you have described is Real Life in a nutshell. And, a(nother) great reason to stay with the original carburetor based fuel system.

 

[giantpune]

Its been a while and that little voice in my head is back telling me to try out some sort of EFI conversion. If I'm wanting to prioritize being able to roll the process back in the event that it doesn't work well or I can't get spare parts, what is the least invasive route?

I think a sniper style setup that mounts to a carburetor pattern lets you do EFI with the least amount of modifications to the engine. Where I'm stuck is the fuel system. It looks like all the options I've seen require replacing the whole tank, cutting a big hole in the top of the tank for a new drop in pump, or at the very least drilling a hole somewhere to install a bulkhead for the return line.

There doesn't look like enough room on the factory sending unit to install the return bulkhead.
I have seen people saying they install the return into the fuel filler neck. Thats in the trunk. From the factory, all the fuel in the trunk area is separate from the passenger compartment by steel. I'm not overly excited about the idea of running a high pressure rubber fuel line and adding in more fittings and gaskets that may eventually leak. Any fuel leak you created by adding a bulkhead to the filler neck would not be sealed away from the passenger compartment.

How else are guys handling the return lines? Short of running the holley "returnless" intank pump which requires cutting a huge hole in the tank anyways.

I do see a number of different sending units for other year mustangs that have a return line right there on the sending unit assembly. They make them for 65-68, 69, and then look like they skip to the 80s mustangs. It would be nice if they would make one for our cars. If not, maybe we can drill a hole and weld in a new tube to the sending unit.