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No sniper. My local vette shop will not recommend them or install them. Too many clearance problems, heat & software issues, etc. C3 has sniper fit issues with throttle, fuel bowls, fuel lines, air cleaner, hood, etc.
They say go Terminator X with a 4150 style throttle body, and has a remote ECU.
Fits & works perfect. Bolts on & fits just like a regular Holley.
Last edited by leigh1322; Mar 30, 2025 at 03:51 PM.
I spent a lot of time and effort to make my Sniper 1 work the way they should work. If you are willing to learn how to tune them, and get around the various problems that arise, they can work great. With that being said, if I could do it all again, I would do as Leigh stated and gone with the Terminator X stealth. More options, ECU stability, more user defined capabilities, etc. Keep in mind that the tuning and tables are still going to have to be tuned by you (or pay someone else) for your car. The Sniper software is essentially a watered down version of the Terminator X software.
However, to answer your initial question: I use the Weiand Team G single plane PN 7530 for SBC. It fits under a L88 hood. I would try to do something similar for the big block if possible - although I am less familiar with LS5 BBC and parts availability/compatibility.
Well for a stock BB you have four intake choices:
I do not know if any EFI option is perfect, so I'll just mention pros and cons.
If you want to fit under the stock BB hood.
You will need to use a similar-to-stock low profile intake.
The top stock GM intake manifolds, the OEM cast iron or the 68/69 L36 aluminum version, are very short.
With the GM open element drop base they give 1.25" of hood clearance.
I measured that. (The 72 twin snorkel is 1/2" taller, so it would have 3/4" hood clearance.)
But these two intakes fit spreadbore QJets.
The LS6 alum intake is the same height, is repop'd and fits a square bore Holley. Dual plane.
There is a rectangular to oval port mismatch, but many have used it and it does not seem to cause driveability problems.
This ?may? be the lesser of all evils.
The Torquer II is still available, takes a square bore carb, is a single plane which is frequently recommended for EFI, but has a 2500rpm and up power band.
Not ideal for a 5000 rpm LS5. It will chop some lower rpm TQ.
A Performer intake just does not fit well under a stock BB hood. It is 1.3" higher and kills all available hood clearance. Your only option is to use a much shorter air filter, which hurts HP, defeating the purpose of the Performer. With a 1.5 to 2.0" high filter in the GM drop base, it may clear.
Holley also makes a QJet spreadbore version of their EFI.
That one would let you use either of the stock GM iron or alum spreadbore intakes, and fit like factory.
So it is the easiest version to bolt on a BB.
It retains the dual plane intake.
But the Terminator seems to have a better ECM/software.
That could be the easiest choice.
It is not recommended to run the 3/4" thick square to spread carb adapters, but that is another option, but it chews up a lot of your available hood clearance. They sometimes have bad fuel distribution / weird driveability issues.
Here is a video of what was involved to put EFI on a C3. 70. SB.
They used a Sniper I, which is no longer available, and had it's own issues.
But the video is pretty good.
I am helping a guy now with a 70 LS5, get his Sniper II to fit under the hood.
The stock intake is coming off, because it has a 3/4" adapter on it, a Torquer is going on.
His GM twin snorkel air cleaner almost fits.
But he is switching to a GM open element for looks.
Either will need a modified air cleaner base b/c the air pipe does not fit with a Sniper.
It does not clear the fuel lines at the back of the "carb" unit.
Same as a 4150 DP does not clear that pipe, but a 4150 vac sec does.
He'll wind up with a filter can on the valve cover.
Not a terrific combo, but the Sniper was already installed, when the shop found out the hood wouldn't close.
The shop had no idea how to fix it, so they sent it home to him like that, undriveable. ?!?!
He would have been better off with either the QJet or the Terminator version.
Both clear that air pipe on the air cleaner.
His ?clueless? shop literally told him: "I hate working on Corvettes. Don't bring it back."
Under the Sniper II you can see the adapter that is causing all the hood problems. The fuel line in the back, marked "in" will not let the air pipe from the air cleaner fit. So the shop ripped the pipe off his OEM GM air cleaner. Taped it up with duct tape, and put the Moroso filter on the valve cover, and it still hit & marked up the hood. Less than 1/4" hood clearance, just not enough. Really nice car. He was not happy with the last shop.
Last edited by leigh1322; Mar 31, 2025 at 11:50 AM.
I have a HolleyStealth Sniper mounted on an EdelbrockRPM Air Gap dual plane intake manifold and I am using a factory L88 Hood with the air box on it. I was able to get everything under the hood and close it and seal the way it was designed to work. The Stealth Sniper is rotated 90* from the basic Sniper system. I specifically chose it because it fits on the engine just like a Holley Double-pumper like I used before. The wedding cake parts for the L88 Hood worked with the EFI system. The nice thing is that the intake (Combustion) air temperature is so close to ambient that you are not loosing power to the pre-heated air like so many Corvettes do. Using air from under the hood increases the potential for detonation. This is why GM designed the L88 Hood with the air box on it. The air box is the best feature of a L88 hood.
If I were to do the system over I would do as suggested above and use a Holley Terminator, a dry throttle body (they make them very short) and an intake designed for multi-port fuel injection. I already have the 58 psi that is required for the Sniper so it will not be as bad as it could be. Learning the Holley Sniper is different but not that hard to understand if you have worked on EFI cars before. The online software package is incredible as it allows you to tailor the settings for your specific engine.
When you are ready to get serious I would strongly suggest that you speak with the folks at efisystempro.com or use this link: https://www.efisystempro.com/. This company is located in Florida and has the best support I have seen for those who want to convert their own car to EFI. I had budgeted for a new tank and planned on spending $2500 for the system. The guys at efisystempro were able to get me everything for several hundred dollars (0ver $700 LESS) than I had budgeted. Efisystempro has a plan where if you buy from them they will give you 24 months of unbelievable tech support to get you and your system working happily. They have a Holley Expert who works for them who contacted me a day after I bought my system, before it even arrived. He gave me his cell number and email address so I could get help from him when I needed it. He is a Tier 3 Holley Technician with Holley and is VERY knowledgeable about EFI systems and components. You can call them or go to their website and tell them what you have car wise, and they will help you design a system for you that will work great. Their web site is chock full of information on the Holley EFI parts and they have tons of questions with answers posted on their web site. I go and just read, as I learn a lot that way from their questions and answers.
Efisystempro keeps a large inventory and ships it fast, not to mention they sell Holley parts at a slight discount. I bought from them because of the service, I was not positive that I could do it. I did not need much help but it was nice to know it was there IF I needed it.
Best regards,
Chris
The Holley EFI system on my L88 Clone has had no issues with fuel distribution as the Edlebrock Intake manifold has a "cut" center divider in it. This allows the RPM air gap to be used with the Holley equipment where other companies who have a solid center divider in the manifold cannot. There are a lot of intakes that are problematic with the Holley EFI system so it can be challenging for a new to EFI person. Talk to an expert and you will have a great system that can and will work on your C3. I can't wait to get a terminator or even a Dominator EFI controller...
Last edited by ctmccloskey; Mar 31, 2025 at 12:57 PM.
