Carburetor, MSD, Holley Sniper EFI questions

-

Kipprc

FABO Gold Member
FABO Gold Member
Joined
May 29, 2020
Messages
117
Reaction score
31
Location
PG County, Maryland
I have been trying to quietly learn about carbs, MSD and EFI by reading a lot of old post along with articles written online. I find that I am still left with questions. I still have a carburetor on the car, but I am putting together the parts for an EFI setup. The fuel system is on the way, but I haven't ordered the Holley Sniper yet. The fuel system portion of EFI looks simple enough, but the actual wiring of the 7 pin and 10 pin connectors is throwing me. When I get all the pieces in, I wouldn't be installing this until October or November anyway, unless I find myself with some extra days off. I want to sure I can get the job done in a day.

1. Is MSD 6a just a better form of electronic ignition?

2. Is it better to run MSd 6a along with an EFI setup (leaning towards Holley Sniper)?

3. Is there any benefit to running an electric fuel pump with a return to a carburetor?

4. On the Holley Sniper ECU wiring diagram do the 7 pin and 10 pin go back to the cluster of wires on the firewall?

5. Once installed can all of the old oem chrysler ignition stuff just be removed and trashed?

I'm just a guy with a garage and some tools. I have no formal mechanical training. So please dumb these answers down. I have never owned a car with a carburetor till now. The most I ever had to do with EFI was fumble with fuel rails and replace injectors. This will be a new experience for me. Thanks in advance.

Photos added for reference

20200806_095224.jpg


20200806_095214.jpg
 
If you’re buying all new anyway I would recommend buying the complete Holley ignition system too.

go onto holley’s website, you should be able to download the complete instructions for the installation of the sniper unit which will answer all your questions
 
I have had my Sniper a couple years. Big learning curve for me, early issues but pretty happy with it as I learn it. Still learning it, just enabled the timing control this year. There is a Holley Sniper owners and tech page on Facebook, lot of info there. I would suggest to run it without the timing control At first to eliminate any issues there. Also put shielding around all the wires. EFI is a big issue with them and it’s a lot easier putting it on outside the car versus once installed. I don’t have the MSD 6a, just a coil with the supplied coil driver. I kept the ballast resistor but ditched the orange box. Recommend relay for pink wire, think through how to connect it as it needs to be powered in both start and run. My sniper has its wires come off the back, plenty to reach the firewall.
 
If you’re buying all new anyway I would recommend buying the complete Holley ignition system too.

go onto holley’s website, you should be able to download the complete instructions for the installation of the sniper unit which will answer all your questions

I have been go going to Holleys website for a couple of weeks now. Thats how these questions got into my head. I may have to actually give them a call. I just want my knowledge to be better so I don't get sold something I don't want or need. Buying their complete ignition system sounds like solid advice. I'm pretty sure whats under the hood now isn't made anymore.
 
Please post links to the documents you are referring to. However, most of these aftermarket EFI systems are designed to function with many different ignition systems

There is a VAST difference however between some ignitions

Older Breaker points (Kettering), the Mopar breakerless, and GM HEI function sort of the same. That is, they switch the coil NEG to ground, and open that connection to make the spark

The MSD or and other CDI (capacitive discharge) is a whole different animal. Those systems charge a big capacitor, much like a photoflash, and the trigger causes the circuitry to discharge that cap into the coil in the form of a high power pulse. MSD is just what it says Multiple Spark Discharge.

An important difference between MSD and any other switched igntion is that you CAN NOT trigger off the coil. Nothing at all should be connected to the ignition coil with CD/ MSD EXCEPT the two coil wires from the ignition system

A trigger for other purposes such as the EFI must be done according to the individual EFI destructions
 
"Is it better?"

2. Is it better to run MSd 6a along with an EFI setup (leaning towards Holley Sniper)?

Not necessarily I'm big on using a GM HEI module, and many others on here have as well

3. Is there any benefit to running an electric fuel pump with a return to a carburetor?

I sure think so, helps prevent boiling/ vapor lock problems. If you go EFI you will most certainly need a return. I believe ?? the Sniper is set up for that

5. Once installed can all of the old oem chrysler ignition stuff just be removed and trashed?

Yes but if it works now, you can just go ahead and run it with something such as Sniper


4. On the Holley Sniper ECU wiring diagram do the 7 pin and 10 pin go back to the cluster of wires on the firewall?

On this page:

Sniper EFI Installation Guide - Holley Blog

they are referring to alpha pin designations ABC, not numerical
 
Last edited:
I think my post absolutely shows that I do not know as much as I should about EFI. I do know I am going that route, but I have to do more reading. I think my biggest stumbling block is that I have not seen a step by step for a mopar anywhere. I have seen the wiring diagrams on Holley's website and I downloaded the Sniper instructions. I watched some install videos on YouTube, but I still don't have a feel for a install should go. I'm still a ways out from doing this so I have time.
 
The sniper is actually pretty easy. Tuning any of them is yet another learning curve, I am certainly no expert on that one.
 
I think my post absolutely shows that I do not know as much as I should about EFI. I do know I am going that route, but I have to do more reading. I think my biggest stumbling block is that I have not seen a step by step for a mopar anywhere. I have seen the wiring diagrams on Holley's website and I downloaded the Sniper instructions. I watched some install videos on YouTube, but I still don't have a feel for a install should go. I'm still a ways out from doing this so I have time.
To be honest and don’t take it the wrong way ok, if you really don’t have any jest on these things believe me they are not plug and play as Holley states and all you will be doing is pulling your hair out running into issues . I’m not sure the 6 A box will cut it if you want to run the timing as well as I think they are the analog type some one will correct me if I’m wrong. You can use it as a stand alone unit without the timing control. The master kit with inline pump are junk better to run in-tank pump. When their on and running correctly they are awesome , easy to tune via laptop as these are things you will need to do so if your half cocked stay with the carburettor and save your self pain and sufferings. Just my 2c
 
I second 67 gt. If you're not up for it, moving over to efi is a bear. I did it on my Coronet, been running FiTech for 3 1/2 years. The terms "plug n play" and "learns as you drive" are marketing slogans. If you try installing and tuning the system yourself you'll end up joining about 1/2 dozen forums and scrolling through hundreds of pages of posts to learn why your car i) won't start cold, ii) won't start warm, iii) won't start hot, iv) suddenly dies while driving down the freeway, v) surges at idle, vi) dies at idle. I could go on and on but you get the idea; and that's post install. Before that you'll have drop the gas tank, upgrade your fuel delivery system from stem to stern, possibly upgrade your charging system, figure out how to get power at both start and run, figure out your ignition system. I'm just getting warmed up.
I know there are scores of enthusiasts that love their efi, and just as many that despise it or went back to a carb. A lot depends on how you use your car. If you drive a couple thousand miles a year mainly to car shows and around town, stop and consider if the time, money, and learning curve are worth it. If you do decide to go for it, this is a great forum to be a member; lots of guys have had success with their efi installs.
 
It may be a bear, but I believe I can do it. Its more about learning as much as I can before I do it. I have the fuel system and tank. It is the areomotive setup. Thats why I wanted to know if there are any benefits to getting rid of the mechanical fuel pump. I may run the tank for a bit without the Sniper. Then later on I will buy and install the Sniper.

Now the trouble shooting of cold starts, hot starts, and dies while driving absolutely have me concerned. I want to go to EFI for easier starting. The car takes a enough energy to start already. I also would like to take a few road trips and I don't want elevation, etc. to cause me problems after sitting overnight. The wiring on this car is pretty old. Starting the car I have to pump the pedal 3 times, turn the key and keep my foot on the pedal for a minute or two. After that the car may decide to stay on or it may cutoff. I am willing to do what it takes to stop doing this dance with the car when I want to drive it.
 
Kipprc
Just trying to figure out here why you are having issues starting your carberated setup right now, with extended cranking and multiple pumps in the throttle to get it going ??

Have not heard what engine, carb, or ignition you are now running. Or what starter you are using.

Having your carb set right along with proper ignition timing and good clean non-ethanol fuel, the single best thing you can do for starting is install the newer generation Mopar high torque Mini Starter.

The thing with the mini starters is that they spin much faster, and they are engineered to take way less electricity away from your already good ignition system, not starving it for spark.

Every time we put a mini starter on the the mopars, we just sit back, smile and say: it starts like it has fuel injection.
Starting Immediately

Was at Cruise In in town here this Wednesday, a guy came in with an 80s Ford 302 mustang with the Sniper Fuel Injection setup, nicely done. Was getting time to leave, he said wonder if it is going to start ?

Unfortunately No Joy, he cranked and cranked, letting the starter cool in between attempts for over a half hour messing with it. Had his laptop out and plugged into the harness, still no joy.

Then finally After 10 some attempts it started spitting and sputtering and started, and then ran fine. Not knowing what the problem was, and he drove away headed for home.

Walked over to the '76 Dodge D100, half stepped the throttle on the Edelbrock to set it, hit the key to start it with the mini starter.

Yep, starts like it has fuel injection.

Warmed it up a bit as the show cars were clearing. Then drove off running nice, heading for home.
 
It may be a bear, but I believe I can do it. Its more about learning as much as I can before I do it. I have the fuel system and tank. It is the areomotive setup. Thats why I wanted to know if there are any benefits to getting rid of the mechanical fuel pump. I may run the tank for a bit without the Sniper. Then later on I will buy and install the Sniper.

Now the trouble shooting of cold starts, hot starts, and dies while driving absolutely have me concerned. I want to go to EFI for easier starting. The car takes a enough energy to start already. I also would like to take a few road trips and I don't want elevation, etc. to cause me problems after sitting overnight. The wiring on this car is pretty old. Starting the car I have to pump the pedal 3 times, turn the key and keep my foot on the pedal for a minute or two. After that the car may decide to stay on or it may cutoff. I am willing to do what it takes to stop doing this dance with the car when I want to drive it.
Kipp you will need to get rid of the mechanical pump with FI as it requires 60psi and that pump would be lucky to push 6 on a good day . I’m running the Tanks inc tank with the Walsbro 255 in tank pump. New 3/8 hard lines than braided 6-12 inches each end . Ignition is 6AL with msd distributor not ready to run . Msd 8.0 plug wires are a must as they are the best to use and give the least issues with rfi. I’ve had the system on my car since early March last year and has been faultless but in saying that I haven’t been controlling spark just fuel only and setup distributor curve with springs and those little advance round spacers provided with the unit. I will one day go with the control timing as for now it runs so well and I don’t want to rock the boat as they say !. Ok so your committed best advise I can give is read the setup manual follow it to a T keep dirty wires away from all other wires meaning distributor and coil Power wires. Remember RFI EMI are your invisible enemy as your snipers ecu lives in the throttle body and is exceptable to any noise. It’s not hard you just need to get your head around it all and understand it Take your time in running the loom properly, you must have good earths ! when attaching wire ends do not just crimp only solder crimp heat shrink what your doing is eliminate any possible problems that can pop up . Don’t use the rubber fuel lines provided run hard lines feed in and return only use in small lengths with AN fittings . Last thing weld that 02 bung in don’t use the kit they supply any exhaust leaks prior to 02 sensor will spike the system lean and that girl will dump fuel . Make sure the engine is mechanically good as if it burns oil leaky exhaust you need to address these first as these systems are a little more temperamental than what your carburettor will let you get away with. Sorry long post good luck grass hopper on your adventure.
 
Last edited:
George Jets if I had to guess, I would say I am the problem. When the car starts it runs fine. Right now I am learning everything on the fly here. I purchased the car from out of state at a dealer. I did it the worst way possible which was online. I have always been against that and then I broke my own rule. The car was good for the most part. I changed a few bulbs, installed a more modern sound system and now I am going through the front end. I noticed the car had an oil leak from the oil filter mounting plate and I fixed that with a Canton plate. The car started off as a 6 cylinder and somebody swapped in a 340. The last owner was a Brian Patterson in Oklahoma if anybody knows him. I don't know him, so I don't truly know all that has been done to the car.

I did a post when I first got the car to try and attempt to figure out what carb was on the car. I think it said1450, but I would have to go back and check on that. I remember it had a bold W with a line under it. Could be a knock off for all I know. The ignition is a mopar electric connected to a msd blaster coil (from what I can tell and I could be wrong). I have no idea what starter is on the car, but it is worth checking out when I get the chance. I know you didn't ask for all of this information, but I'm putting it all out there in case it sheds some light.
 
Edelbrock 1406 with electric choke carb is a great running simple carb that works for many mopar small block applications.

Pretty much use this model carb on everything I do. Have not had to do any rejetting on them either, bolt on and go.

Lot simpler that trying to swap the whole car over to EFI.

Screenshot_20200807-121328_Gallery.jpg
 
I had no experience with efi or Mopar ignition systems before I began my adventure. Now I have the Holley super sniper, hyper spark ignition, coil. Wiring them up was easy. I have the tanks inc tank and pump controlled by the efi. I have an internally regulated alternator . Having these pieces I was able to remove the ballast resistor, Mopar ignition box and voltage regulator. It was rather easy to do.
 
I doubt you have a 1450 carb; that's essentially a race carb. The underlined W is the Weber logo, found on Edelbrock carbs - should look like the one posted above.
 
If you have the 1405 Edelbrock carb on there, that is the same carb as the 1406 without the electric choke.

Believe the 1405 carb is a manual choke carb, works with a choke cable, and possibly a hair richer on the jetting than the 1406 too. You can read about them on Edelbrock's web site.

So just guessing here, if you do have the 1405 with no choke, or someone swapped a choke to it but did not set it closed right. Then that would explain why you have to pump it 3 times to give it some gas with the accelerator pump, because no choke or the choke is not closing up far enough to give it the more fuel it needs to start.

Also explains why at first start it is hard to keep it running without your foot on the gas. Pretty obvious the choke is not doing the job or is missing altogether.
 
I had no experience with efi or Mopar ignition systems before I began my adventure. Now I have the Holley super sniper, hyper spark ignition, coil. Wiring them up was easy. I have the tanks inc tank and pump controlled by the efi. I have an internally regulated alternator . Having these pieces I was able to remove the ballast resistor, Mopar ignition box and voltage regulator. It was rather easy to do.
Kent it is easy if you can follow the instructions and put that into practice but some people find that part difficult to comprehend not having a dig at anyone. I’m on the Holley forum both on Holley and Fb , the fb one is pretty good and there’s a lot of good people helping guys out and I see people all the time complaining about this product is **** , I want a refund . There is some issues with the sniper where there has been ecu malfunctioning **** inline pumps not lasting ,**** connectors on the injectors coming loose and causing headaches for customers.when they are asked to run a data log so the people on board can get a better understanding on what’s happening the person having issues wouldn’t have the faintest idea , or just in engine perimeters what engine cu inch what ignition system etc they input wrong info or finding a 12v source as my screen keeps rebooting as I’m cranking ,basic things because people don’t take the time to read the information in front of them or not understanding it . It’s not as forgiving as a carburettor there a steps to be followed to achieve a result. You have to agree though these classics we drive were very basic and than 60 years later here we are integrating later tech Into them Weather to get better performance or fuel mileage so do your research have a plan of attack and just understand on what your dealing with.
 
This is the carb. I will get more pics when my shift ends.

View attachment 1715574401

View attachment 1715574402

OK as you have pictured, there is no electric choke on the Edelbrock carb, and the manual choke Butterfly in the front appears to be wired open. So that means no choke on startup.

20200807_195054.jpg


2nd, the geometry on your throttle and transmission kickdown linkage is way off, moving the kickdown linkage in the opposite direction because it is hooked up below the the throttle shaft pivot and should be above it to get the right push on the kickdown as you are opening the throttle.

See the Factory Mopar Linkage pictured below.

Also you need the Edelbrock to Mopar linkage adapter too, to get your throttle cable and kickdown linkage mounts in the right spots. They are like 15 dollars.


20200807_195651.jpg


Edelbrock Mopar.jpg


Edlebrock # 1481 mopar linkage adapter

1481.jpg
 
OK as you have pictured, there is no electric choke on the Edelbrock carb, and the manual choke Butterfly in the front appears to be wired open. So that means no choke on startup.

View attachment 1715574493

2nd, the geometry on your throttle and transmission kickdown linkage is way off, moving the kickdown linkage in the opposite direction because it is hooked up below the the throttle shaft pivot and should be above it to get the right push on the kickdown as you are opening the throttle.

See the Factory Mopar Linkage pictured below.

Also you need the Edelbrock to Mopar linkage adapter too, to get your throttle cable and kickdown linkage mounts in the right spots. They are like 15 dollars.


View attachment 1715574504

View attachment 1715574505

Edlebrock # 1481 mopar linkage adapter

View attachment 1715574506

Damn man thats masters level carb speak you got going on there. I'm intrigued. I am going to order this part tomorrow... Nevermind, I just ordered it. Just want to see if these changes make a difference.
 
Last edited:
I have been go going to Holleys website for a couple of weeks now. Thats how these questions got into my head. I may have to actually give them a call. I just want my knowledge to be better so I don't get sold something I don't want or need. Buying their complete ignition system sounds like solid advice. I'm pretty sure whats under the hood now isn't made anymore.

I wrote a couple of articles on Sniper install that are on the Hot Rod website. I highly recommend buying the Holley Hyperspark distributor in addition to the Sniper. You can also buy the Hyperspark ignition box and coil or use a MSD box if you have one laying around. If you are buying new parts then just stick with Holley for everything including the fuel pump. Depending on which car you have you might be able to buy a drop in fuel pump from Holley that bolts into your existing tank. That is a really clean solution if it is available for your make and model.

Holley HyperSpark: Install and Tune
Super Sniper EFI Sees Powerful Improvements To Data Logging
 
I have been trying to quietly learn about carbs, MSD and EFI by reading a lot of old post along with articles written online. I find that I am still left with questions. I still have a carburetor on the car, but I am putting together the parts for an EFI setup. The fuel system is on the way, but I haven't ordered the Holley Sniper yet. The fuel system portion of EFI looks simple enough, but the actual wiring of the 7 pin and 10 pin connectors is throwing me. When I get all the pieces in, I wouldn't be installing this until October or November anyway, unless I find myself with some extra days off. I want to sure I can get the job done in a day.

1. Is MSD 6a just a better form of electronic ignition?

2. Is it better to run MSd 6a along with an EFI setup (leaning towards Holley Sniper)?

3. Is there any benefit to running an electric fuel pump with a return to a carburetor?

4. On the Holley Sniper ECU wiring diagram do the 7 pin and 10 pin go back to the cluster of wires on the firewall?

5. Once installed can all of the old oem chrysler ignition stuff just be removed and trashed?

I'm just a guy with a garage and some tools. I have no formal mechanical training. So please dumb these answers down. I have never owned a car with a carburetor till now. The most I ever had to do with EFI was fumble with fuel rails and replace injectors. This will be a new experience for me. Thanks in advance.

Photos added for reference

View attachment 1715573638

View attachment 1715573639

The Sniper instructions will answer some of your questions. The wiring diagrams in the instructions will show you what to do with the 7 pin and 10 pin connectors. Basically you need to hook up to power and ground and then run a wire to your new high pressure electric fuel pump. You'll also need to connect to your ignition system. If you are going to control fans then there are wires for that. There is a tach wire which you may or may not need and a gauge cluster wire which you might not need. If you use a Hyperspark then you use the white wire and remove the yellow wire. It is all very simple once you understand the instructions.

Toss all of the Mopar ignition system in the trash including distributor, coil, ballast resistor, etc. The tricky part for a Mopar install is that you need 12 volts cranking and running so you have to tie IGN 1 and IGN 2 together. Those tied together will send 12 volts to the Sniper and the ignition system.
 
You'll also need new resistor plugs and new resistor type spark plug wires. I use OEM application NGK plugs and FireCore wires on all of my installs. You will want to install a fixed orifice PCV valve to work with the Sniper and you should have an O2 bung installed in both head pipes while you're at the exhaust shop. Make sure the bung is installed correctly so you can access the O2 sensor and the harness. You'll need to install the CTS in the hot side of the cooling system so check to see if you have a 3/8 NPT port in your intake. If you don't have a port then you might need to get one of the thermostat spacers I make for the Sniper. You might also need a Sniper throttle bracket that I make. After doing a bunch of Sniper installs I decided to start making the parts that people needed for a clean install.
Thermostat spacer with EFI sensor port | AR Engineering
 
-
Back
Top