Holley sniper install questions

codfish

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Temp sensor now in the head. I did put the stock sensor in the thermostat housing though for the stock gauge. Not too worried about the looks. It’s soon to be my daily driver.

The battery is a year old. AC Delco 665 CCA. Truck has been sitting for a week or so without being started, but with the battery disconnected.

Perhaps I’ll put the charger on it and retry the voltage while cranking. I’ve got no problem with using a relay though. Have everything I need.

Codfish
 

83c10mike

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Do not "piggyback" sensors, it makes for bad readings on both ends. Put the temp sensor in the other head. It will perform better during warm-ups.

I would avoid the master kit, instead invest in an 87 tank, sending unit an a fuel pump from a 96 C1500 5.7l. In tank pumps are much more reliable an longer lasting.

There should be several ignition sources you can use in the fuse box, just make sure its hot in run AND crank. Otherwise the sniper will power off when you try to crank an it will be very hard to start. Yes I've seen this alot unfortunately.

Power an ground need to go straight to the battery, NO EXCEPTIONS!

O2 sensor, have a bung welded onto the exhaust, don't use the clamp on unit that it comes with. 6-8" after the collector with a minimum of 18" of pipe after it.

Your engine and current wiring need to be in good shape for the system to perform at its best. The units work well as long as the installation is done properly and your willing to invest the time to learn the system and to make it work its best. I've had a sniper on my truck since 2018, I'm still on all the original sensors an I've probably put 30k miles on i
What is your reasoning on using a 96 c1500 sending unit and fuel pump with a 87 tank. Is there something wrong with the 87 sending unit and a pump in an 87 tank? Does the 96 sending unit drop in the 87 tank with no modifications?
 

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What is your reasoning on using a 96 c1500 sending unit and fuel pump with a 87 tank. Is there something wrong with the 87 sending unit and a pump in an 87 tank? Does the 96 sending unit drop in the 87 tank with no modifications?
I have the same setup on mine with a ProFlo4 EFI and use the 87 sending units but with the newer pumps. The newer FI runs at a higher PSI which those newer pumps do nicely.
 

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I have the same setup on mine with a ProFlo4 EFI and use the 87 sending units but with the newer pumps. The newer FI runs at a higher PSI which those newer pumps do nicely.
Yup. Same here. EP 381 pumps btw. OEM for the 90's Vortec engine.
 

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What is your reasoning on using a 96 c1500 sending unit and fuel pump with a 87 tank. Is there something wrong with the 87 sending unit and a pump in an 87 tank? Does the 96 sending unit drop in the 87 tank with no modifications?

The 87 pump doesn't put out the pressure a newer efi system needs. The 87 pump is for about 15 psi, the 96 puts out the 60 psi that all modern efi systems use. It will fit the 87 sender with no mods.
 

Ricko1966

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Just getting into the wiring finally for the sniper. Pink wire question.

I know it needs power while in run and while cranking. That’s understood.

I have a couple empty terminals in the fuse block that are hot in run and while cranking. Only thing is, the volts drop from 12 to about 8.5 while cranking. Is this sufficient?

I’ve searched this topic on many different sites, and EVERY answer just says the source has to be hot in run and crank, not necessarily 12 volts.

Thanks again for the help
Codfish
Run a volt drop test on your positive and negative cables if they are good check amperage draw on your starter.
 

chevytech87

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The 87 pump doesn't put out the pressure a newer efi system needs. The 87 pump is for about 15 psi, the 96 puts out the 60 psi that all modern efi systems use. It will fit the 87 sender with no mods.
This may be a silly question, but I’m about to swap to a sniper on my 87 and was looking into doing the in-tank pump swap as well but I had some concerns about the switching valve being able to handle that much pressure. Am I overthinking or does nobody run dual tanks making the switch an non-issue?
 

bluex

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This may be a silly question, but I’m about to swap to a sniper on my 87 and was looking into doing the in-tank pump swap as well but I had some concerns about the switching valve being able to handle that much pressure. Am I overthinking or does nobody run dual tanks making the switch an non-issue?

The 87+ valve will be ok with the pressure. Any soft hoses and clamps will need to be replaced with EFI rated ones. Most people that try to keep the dual tanks with efi have lots of issues. I personally recommend just sticking with one tank an if you really need the extra capacity use the second tank an the standard 87 pump to transfer into the "main" tank.

From my experience trying to keep the dual tanks just isn't worth the effort and additional expense. If you have an OD trans an the efi you should have decent enough fuel mileage that one tank, even at 16 gal is sufficient range.
 

SquareRoot

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I've done it. No issues with dual tanks and EFI. The "extra effort and expensive is BS". It cost a whopping $25 for a roll of 16 guage wire, a double throw switch and a Bosch relay. The Sniper on the other hand......
 

MarineOne

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If stock intake is dual plan it is essential to graind down the center so that may reads properly or run a spacer
 

RanchWelder

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I called Norm and asked if I can add smaller injectors to the Sniper and he said NO.

He then said, he can mod the injectors so duty cycle is perfect for the build, ^^^^^^^^ before the Holley ships. He engineers the entire system... reprograms everything to match them custom and ships it. In fact he said the program will most like run as shipped the first time it's installed without having to learn anything.

His build get Dyno'd on his Dyno...

Keep in mind, if you read this and say to yourself, "Thanks Welder, I'll just install custom injectors on my NEW Holley Sniper"... you immediately void the warranty and Holley will block your calls for being too smart for your own good... Norm has permission from Holley to do this, YOU do NOT...
He told me he re-maps the entire computer algorithm, so when you program, the injector size changes are now part of the entire program.

How many guys think about this before they try to add an 800HP TBI to their small block 350HP build?
Then frantically try to down tune the injector duty cycle to nearly zero to keep it running?

Let the engineers do the engineering...


We discussed the Heritage Sniper which looks like a double pumper, custom built to your specs. It comes with huge injectors... capable of giant HP... your small block will most likely never run right on them and you are not allowed to swap them out, without a new reprogram of the entire system logic.

Do yourself a favor and check it out...
The price he quoted me was very reasonable, lil more than buying from a retailer would cost, and he becomes your tech support Engineer, not Holley... No long hold with Holley,,, ever...

All the issues these other guys have stated is why the error ratio and the bad parts selection issues concern me. Over injected... bad duty cycle... No clue...

I would not cut a divorced manifold unless it was proven on a dyno first...

I'm not able to tell you the system he built me is awesome... My budget precludes me buying his basic systm at this point in my build... He did answer the phone when I called him...

This seems to be the main complaint when buying without using an engineering company, from Holley forums.

If you expect to bolt on a non custom Holley Sniper the way it ships, I would call Holley and get the exact lift and duration for the cam and engine specs they designed it on. Then copy it exactly.
Your engine may not even come close...



Good Luck!
 
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SquareRoot

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Did the issue with the terrible linkage ratio come up? People with auto trans have learned to live with it. Those with manual trans like me couldn't. I wasn't willing to engineer new bracketry after spending $1000 on a piece of junk that kept failing.
 

bluex

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Did the issue with the terrible linkage ratio come up? People with auto trans have learned to live with it. Those with manual trans like me couldn't. I wasn't willing to engineer new bracketry after spending $1000 on a piece of junk that kept failing.

This $16 part will fix the stiff linkage issue. At this point they should be included on standard 4150 snipers imo.

 

bluex

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I've done it. No issues with dual tanks and EFI. The "extra effort and expensive is BS". It cost a whopping $25 for a roll of 16 guage wire, a double throw switch and a Bosch relay. The Sniper on the other hand......

If you have a 73-86 truck it's alot more expensive than than a roll of wire. You need 2 tanks, 2 sending units, 2 pumps, the 87 valve, switch an full wiring, etc.

Glad you've had good luck with it. Of the trucks I've been involved with the valves fail within a month, we tried deleting them an running check valves an 2 Corvette style regulator filters an had issues with the check valves. It was a never ending trail of problems for minimal benefit of some extra fuel capacity.....
 

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