Holley Sniper Info and Resources

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Joined
Sep 8, 2018
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Ross, Ohio
My Car
71 Sportsroof Bright Red.

Since I installed my new Holley Sniper, I have been doing research on tuning and creating config files for it. I really like the customization that you can do and the log reports that show how everything is running.

While doing this research I came across some interesting info that I figure I would share. I’m for sure that most of you that have Sniper's will be familiar with what I’m posting but for those that are new to these units it might help you out and save you some time and trouble.

Beside YouTube and other places on the web the following site has a lot of info and good how to articles on the Sniper plus all the other Holley efi systems.

EFI System Pro - Your One-Stop Source for Fuel Injection Systems and Information

To get to the section that has the articles and other good info go to the “EFI Pro Hangout” at the top left side of the page. Here you will find info on all the Holley efi’s and some good articles and “How To’s”.


I found that one of the most common problems with the Sniper is RFI/EMI interference. With the ecu enclosed in the throttle body it makes it more susceptible to interference. I found the following article that addresses the issue, and I can see how ignoring proper wiring installation can lead to such problems and cause a lot of wasted time chasing ghost. Here is the link to the article.

Solving RF Interference Issues in Sniper Installations (efisystempro.com)

After following the guide and checking over all my wiring I took the car out for a run so I could log some data and check to see if I had any interference. Upon reviewing the log all looked great. Here is a screen shot of the log. All sensors are showing stable with no signals crossing over another.
RFI - EMI Graph  (2).png

I have also read several other articles where guys have made shields to address interference problems. Although I don’t agree with using a shield to fix a rfi/emi problem, I can see having one to prevent issues from occurring if the alternator or other electronics were to fail. It would provide a band aid until you got the real problem fix.

Knowing that my install was clean with no interference I decide to go ahead and make one. Here are the dimensions that I used to make it if you are interested. I used 22 ga sheet metal so I could tuck the upper edge under the Sniper’s top lip. Make sure that you have a good ground when you bolt it on. You will also need to be aware of your air cleaner clearance. I have a 1 ¼” drop bottom and it just clears the outside corners of the shield. You will have to overlook my great artistic rendering of the template.


20211229_161235_resized.jpg

20211229_135420_resized.jpg 20211230_105626_resized.jpg 20211230_111427_resized.jpg 20211230_111032_resized.jpg

I ran another log after installation, and everything still looked great.

The next issue I read about is the linkage. Besides having to make a bracket to move my throttle cable out away from the manifold to keep it in line with the Sniper’s linkage it seems that the Sniper is touchy when it comes to the throttle by being oversensitive to input. To address this issue Holley has come out with a throttle level extension. The extension creates a longer leverage point giving you more input control, so the throttle is not as touchy. They cost around $15, or you can make your own as I did. The bottom hole to center hole is about 2 1/8” and the top hole is 1” above that. I tried to scale from several pictures I found online.


20220102_122533_resized.jpg

Before running out and buying one or making your own there are several things to be aware of. The first issue that arises is clearance with the bottom of the air cleaner. In my case of having a 1 ¼ “drop air cleaner the arm was hitting it. To correct this, I cut out the bottom of the air cleaner and made box for the arm to pass through. I sealed up all the cracks around the edges. It ended up taking a couple of hours to modify the air cleaner.


20220102_153854_resized.jpg 20220102_153905_resized.jpg

The second and the bigger of the issues is that our throttle cables have approximately 1 ¼ “ of max travel which poses a problem when using the extension. By moving the linkage ball father away from the pivot point on the extension it causes the need for a longer arc (chord) travel length to get WOT. As our cars are currently set up, there is not enough travel length in our throttle cable to get wot when using the extension. It reduces the throttle to about 60% of full travel. The only way to gain this extra needed travel is to modify the gas pedal travel and go to an aftermarket adjustable throttle cable. You will need to pick up at least an extra inch or more of cable travel to get to WOT. See diagram below.

The top drawing is factory length, and you will be able to get to wot. The bottom is after adding extension which will only give you about 60% of wot due to not enough arm travel.

Extension Diagram (2).jpg

It wasn’t until I had completed all of this work that I found out I didn’t have enough throttle cable travel to be able to use the extension. For the time being I have taken the extension off. I will decide in the near future if I’m going to replace the throttle cable and modify the gas pedal or leave it as is.


I hope this will help some of you out and keep you from having issues.


 
Joined
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Philadelphia
My Car
73 Mach 1
I had RFI when I 1st installed mine. Lots of research lead me to grounding. I went overboard after reading and ending up wrapping most of my wires in copper tape and grounding them on both ends.
Later I found a guy in Australia who makes similar to what you've done. Looks clean.
One of the biggest gains I believe was from the plastic thread for the air cleaner. That thing can act like an antenna!
I can't say for sure if any one thing fixed it or the combination of all but I know my setup runs like a champ.
I've driven my car to work (50miles) many of times in the summer and fall. 95 degree days have my electric fans turning on at 195 and 200. Both turn off at 185. Car never over heats and shes a 408c.
With the aeromotive fuel tank/340pump, hydraboost brakes, hydraulic clutch, TKO 600 and EFI it's a pleasure to drive.
 

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machphil

Active member
Joined
Feb 23, 2018
Messages
39
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Location
Illinois
My Car
'71 and '73 Mach 1's.
Since I installed my new Holley Sniper, I have been doing research on tuning and creating config files for it. I really like the customization that you can do and the log reports that show how everything is running.

While doing this research I came across some interesting info that I figure I would share. I’m for sure that most of you that have Sniper's will be familiar with what I’m posting but for those that are new to these units it might help you out and save you some time and trouble.

Beside YouTube and other places on the web the following site has a lot of info and good how to articles on the Sniper plus all the other Holley efi systems.


EFI System Pro - Your One-Stop Source for Fuel Injection Systems and Information

To get to the section that has the articles and other good info go to the “EFI Pro Hangout” at the top left side of the page. Here you will find info on all the Holley efi’s and some good articles and “How To’s”.

I found that one of the most common problems with the Sniper is RFI/EMI interference. With the ecu enclosed in the throttle body it makes it more susceptible to interference. I found the following article that addresses the issue, and I can see how ignoring proper wiring installation can lead to such problems and cause a lot of wasted time chasing ghost. Here is the link to the article.

Solving RF Interference Issues in Sniper Installations (efisystempro.com)

After following the guide and checking over all my wiring I took the car out for a run so I could log some data and check to see if I had any interference. Upon reviewing the log all looked great. Here is a screen shot of the log. All sensors are showing stable with no signals crossing over another.
View attachment 58630

I have also read several other articles where guys have made shields to address interference problems. Although I don’t agree with using a shield to fix a rfi/emi problem, I can see having one to prevent issues from occurring if the alternator or other electronics were to fail. It would provide a band aid until you got the real problem fix.

Knowing that my install was clean with no interference I decide to go ahead and make one. Here are the dimensions that I used to make it if you are interested. I used 22 ga sheet metal so I could tuck the upper edge under the Sniper’s top lip. Make sure that you have a good ground when you bolt it on. You will also need to be aware of your air cleaner clearance. I have a 1 ¼” drop bottom and it just clears the outside corners of the shield. You will have to overlook my great artistic rendering of the template.

View attachment 58623

View attachment 58622 View attachment 58624 View attachment 58625 View attachment 58632

I ran another log after installation, and everything still looked great.

The next issue I read about is the linkage. Besides having to make a bracket to move my throttle cable out away from the manifold to keep it in line with the Sniper’s linkage it seems that the Sniper is touchy when it comes to the throttle by being oversensitive to input. To address this issue Holley has come out with a throttle level extension. The extension creates a longer leverage point giving you more input control, so the throttle is not as touchy. They cost around $15, or you can make your own as I did. The bottom hole to center hole is about 2 1/8” and the top hole is 1” above that. I tried to scale from several pictures I found online.


View attachment 58626

Before running out and buying one or making your own there are several things to be aware of. The first issue that arises is clearance with the bottom of the air cleaner. In my case of having a 1 ¼ “drop air cleaner the arm was hitting it. To correct this, I cut out the bottom of the air cleaner and made box for the arm to pass through. I sealed up all the cracks around the edges. It ended up taking a couple of hours to modify the air cleaner.


View attachment 58628 View attachment 58629

The second and the bigger of the issues is that our throttle cables have approximately 1 ¼ “ of max travel which poses a problem when using the extension. By moving the linkage ball father away from the pivot point on the extension it causes the need for a longer arc (chord) travel length to get WOT. As our cars are currently set up, there is not enough travel length in our throttle cable to get wot when using the extension. It reduces the throttle to about 60% of full travel. The only way to gain this extra needed travel is to modify the gas pedal travel and go to an aftermarket adjustable throttle cable. You will need to pick up at least an extra inch or more of cable travel to get to WOT. See diagram below.

The top drawing is factory length, and you will be able to get to wot. The bottom is after adding extension which will only give you about 60% of wot due to not enough arm travel.

View attachment 58633

It wasn’t until I had completed all of this work that I found out I didn’t have enough throttle cable travel to be able to use the extension. For the time being I have taken the extension off. I will decide in the near future if I’m going to replace the throttle cable and modify the gas pedal or leave it as is.

I hope this will help some of you out and keep you from having issues.
Are you running a 429 Blue Thunder intake?
 
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