Holley Sniper EFI install on my 258

gr8dain

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Ashburn
State
VA
#1
I intended to take a bunch of pictures and make sure I document my experience installing the Sniper on my Scrambler. I probably did not get enough pictures or take enough botes, but here goes.

To start off, I replaced a Holley 4bbl carb mounted on an Offenhauser intake. Is it more carb than needed on this engine, yes. But it came attached to the engine I swapped in a number of years ago. And I felt it was easier to get the 4bbl Sniper than to swap back to a stock intake. So with Christmas gift $$ and a lot of my own added, I purchased the 550-511k Master kit
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First step was to remove the old carb. Here is a “before” pic. Then without the carb.

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Last edited:

gr8dain

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Ashburn
State
VA
#2
Next was to remove the plug in yhe bung on my Borla header for install of the O2 sensor. The kit comes with a clamp on adapter if you want to drill and clamp the sensor on, but I would have welded a bung in anyway. Luckily the header had one. I did soak the plug in pb blaster multiple times starting a week ahead. Luckily it only took a little persuading to get the plug out. And then the O2 sensor went in easily.
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gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
#3
Next, the new unit was installed onto the manifold. The gasket under the old carb had a little matterial missong between the large holes, so I used a little gasket maker to seal it up a bit. The sniper fit perfectly on the intake. And the relay and fuse were mounted along the firewall.
DDD4FF49-0B5B-431D-BB03-5AFFB79DB7A1.jpeg
 

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
#4
While my friend Rob was complaining about my wiring for the e-fans I have installed and taking the effort to clean it all up, I went under the back with another friend to work on the fuel line and pump and filter install. There is a pre-pump filter and a post-pump filter. Here is where I deviated from common practice. Since the pump is a gravity fed external pump, most say to mount it on the frame rail in front of the rear wheel. But it is also best to keep the pump as close to the tank as possible. Garner (the friend assisting with the lines) has an EFI on his CJ and mounted his pump on the cross bar in front of the tank. His has been working great for about a year. And he wheels it hard. He did it there for better protection. I took his advice and mounted my pump in the same place. And I ran the wiring through the frame rail. 1C1F4B97-5275-4231-9003-D8CEB106E7E8.jpeg 96873C18-60AB-4D6E-8144-DC924527E2F4.jpeg
 

gr8dain

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City
Ashburn
State
VA
#5
To power the unit, we needed a switched power that would be hot after cranking. Since the wire leading to my “Batt” terminal
On my HEI coil would no longer be used, we took that spare wire and hooked it up to the pink power wire on the Sniper.
367CB6F6-7B46-4A3C-B6C6-DAEB11898C10.jpeg
 

gr8dain

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CJ-8.com Member
City
Ashburn
State
VA
#6
More wiring by Rob. He was taking the Flex-a-lite controller for the e-fans off and wiring the fans into the Sniper using the supplied lines. But we needed a relay and pigtail to do that. And my positive battery cable terminal broke as we were disconnecting it, so I ran off to three different auto parts places looking for parts. While doing that, Rob cleaned up wiring.
8D84EFBB-E593-4E5B-90BD-25F69FFEA923.jpeg 0F2F3501-1A98-45B8-B2CF-59826C4BD8AB.jpeg
 

gr8dain

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City
Ashburn
State
VA
#7
After plugging everything together, it was time to try it out. Went to the key and put it to On. Nada. Hmmm. What happened. Tested power, that was good. Relay worked, pump was getting power.......... Turnednout that the module/display that was run to the cab was plugged in but not far enough to hear the click. Once we got the click, we tried again. Turned the key to On and the display lit up. We follwed the directions to get an initial read and format the memory card, etc. cycled it off. Then turned it on, wait 3 seconds to prime the fuel line, then fired it up. I could not believe it turned right over. I have a video of the run, but can’t uplaod it. So here is a picture of the final install.
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gr8dain

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City
Ashburn
State
VA
#9
What do I have left? Well, I have an issue with the temp sensor. Holley recommends using the spot on the back of the head. I cannot do that since an old sensor broke off in that spot years ago and to keep it from leaking, the area got filled with JB Weld. But I have a bung for two sensors spliced into my radiator hose. So I thought I would use the one that used to control the fans since I don’t need that one anymore. Well, it is not being nice and coming out. So I will work on that today. If I can get it out, I will screw in the Holley sensor and make sure all is good and the fans turn on.

Almost there.
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
#11
Thanks for the update Dain I'm still putting my 258 together. I purchased the 2 barrel sniper because I have the original manifold and just figured the 4 would be to much even though it is all adjustable and programmable. I went with the intank pump also. Looking forward to seeing how it all works.
 

gr8dain

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City
Ashburn
State
VA
#12
So does the display show RPM / AF ratio / loading / throttle % in real time?
Yes it does. And the display can be configured to show whatever you want really. I will ipdate with a pic of the display in a bit.

I got the stuck temp sensor out this morning, but the Hilley sensor is too big for the bung. Getting a new bung from a friend in a bit. Then to try again.

My fans never came on as I don’t think the sensor was getting up to temp since I had it pressed between two hoses and not really in the coolant.
 

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
#13
Thanks for the update Dain I'm still putting my 258 together. I purchased the 2 barrel sniper because I have the original manifold and just figured the 4 would be to much even though it is all adjustable and programmable. I went with the intank pump also. Looking forward to seeing how it all works.
I was tempted by the in tank pump. But I am going to test this one first. The pump they sell did not have a sending unit so I would need to drill another hole in the tank. There is a company that sells a drop in pump with sending unit that fits the CJ tank but I cannot remember the name.
 

tower210

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City
Olathe
State
KS
#14
If you have the same radiator hose bung I have; it might not be what you need. I think my hose that has the bung only sees coolant after the t-stat has opened; which won't be until 160-200..... Maybe the fan shouldn't run before then anyways.....

Does Holley recommend a higher T-stat with the FI? I know the 4.0's use 190F tstat to run best....

I've heard of people using 4.0 tstat housings as they have a temp sensor bung in them; I tried this when I had a 258; but it sticks out slightly different and hit my serp belt (I had one of the rare California models with a serp belt) - pretty sure it didn't hit the V-belt; cause others had used that housing....
 

gr8dain

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Ashburn
State
VA
#16
If you have the same radiator hose bung I have; it might not be what you need. I think my hose that has the bung only sees coolant after the t-stat has opened; which won't be until 160-200..... Maybe the fan shouldn't run before then anyways.....

Does Holley recommend a higher T-stat with the FI? I know the 4.0's use 190F tstat to run best....

I've heard of people using 4.0 tstat housings as they have a temp sensor bung in them; I tried this when I had a 258; but it sticks out slightly different and hit my serp belt (I had one of the rare California models with a serp belt) - pretty sure it didn't hit the V-belt; cause others had used that housing....
I could not use the sensor location at the back of the head due to a previous sensor breaking in half so I have to use the hose at the t-stat. I know it is not optimal, but as you mentioned, the fans won’t turn on until it hits that higher temp anyway.
 

jbeemer

CJ-8 Member
CJ-8.com Member
City
Conklin
State
MI
#17
I'm not positive, But I think the Holley need continuous temp signal. The temp sensor will adjust fuel, timing, idle, etc... before the T-stat opens. Like I said I'm not positive, but that is how my Holley Terminator was.
 

tower210

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City
Olathe
State
KS
#18
I'm not positive, But I think the Holley need continuous temp signal. The temp sensor will adjust fuel, timing, idle, etc... before the T-stat opens. Like I said I'm not positive, but that is how my Holley Terminator was.
This was my concern. It may adjust fuel mixture before the t-stat opens based on temps....
 

gr8dain

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City
Ashburn
State
VA
#19
This was my concern. It may adjust fuel mixture before the t-stat opens based on temps....
I have/had that concern. But I don’t have much choice. I could not use the location at the back of the head. And a couple mechanic friends who have done FI conversions on CJs before said that location would be bad anyway and the best spor is in that heater lone I used. So at worst, I run rough until the engine heats up. Best I can do.
 

gr8dain

Scrambler Junkie
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City
Ashburn
State
VA
#20
By the way, it stalled twice today. Once on the way to work. And once on the way home. I think both were before it warmed up. I am going to keep an eye on it. Maybe I adjusted the idle screw too low. May play with that tomorrow.
 
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