So I'm considering the Sniper Quadrajet EFI system for my 68/427/400hp. Has anyone used or heard any good or not so good feedback. This car is going to be given to my daughter and want it to be as easy as possible for her.
I'll be attaching it with a cast iron intake (3955287)from a 70-71 454 that was used on the car when I purchased it BTW.

Thanks all,
Jim

 

Lots of threads. Information on here about intake manifolds and EFI. I even ran a thread myself a couple years ago on this very topic. I am thinking a google search would net you a days worth of reading.
Bottom line, low profile duel plane manifold with EFI is highly likely to give you tuning problems that just can't be solved.
Better to get a low rise single plane manifold, if you can find one for a big block.
Otherwise, the Holley sniper EFI gets rave reviews.

 

There is a member here....Tom something, that put one on his 69' 427/390 (Q-Jet) and had nothing but trouble getting it to run right. Granted, the way he went about troubleshooting it and relying on Holley was a little touch and go, but the problems he had were valid......it just ran fat and nothing he did could change it. But the first mistake he made was buying it direct from Holley.......I could go on for days, but after being in the industry for 6-7 years at the front line and working on Hot Rods/Vettes for 35 years.......those who know...know that Holley is a big box entity that could give a **** if what you bought works or not. I still use Holley products because their money goes to R&D and most of their equipment works as intended and is hard to beat....including the Sniper, but customer service is a crap shoot.....and the good reviews they have for service on the internet I am almost certain are fake.
That said....I have installed two Sniper's and they work well on both...but here is what you need to know:

1) Do not use it without their Hyperspark ignition. Unless you are an engine and wiring wiz, using anything but the Hyperspark is a pain in the ***.....and not using the timing control all together is a complete waste of money....keep your Q-Jet. BUT, the Hyperspark is plug and play and the car will fire right up......the parameters will set and it will run as intended. The phasing tool they offer for the distributor is super easy......I setup the whole system, wired it, and had it running in 1.5 hours with a helper mounting the equipment in a K5 Blazer.

2) Do not buy it from Holley or the Big Box chains. The only place to buy one of these units is EFIsystems Pro. If you purchase the unit from them....you get instant, human support....and they are extremely knowledgeable about what to do in certain situations.......they have online tech write ups as well. The member I mentioned above with the 69' had his problems solved by EFIsystems Pro quickly after screwing with Holley for over a month......the car is a beautiful 70k Resto build....search for his thread here and gain some valuable insight.

3) Spend time routing fuel lines and wiring. I can't stress this enough.....with fuel and electrical routing, if it looks good, chances are it is good......There is a retro fit tank module for Vette's that makes the fuel question very easy......but the longitivity of these self regulating pumps is still not determined. Out of the way of everything is the golden rule......especially with the electrical as the Sniper can be very sensitive to RF noise from other electrical components and this is well documented. Fuel systems should be setup so everything is accessible and easy to repair/change out.

4) I agree with the single plane manifold deal. Unless Holley changed it......the MAP sensor for these is only on one primary barrel. A dual plane has two distinctly different sets of signals it gives to a carburator...and one side of the primary will not know what the other side is doing although the computer will deliver fuel using the data from the one side of the primary. If the other wants a silightly different fuel curve, it will not get it. This discrepancy increases when airflow demnds increase as well, it will be more of an issue with a 600hp dual plane setup than a 400 horse. The dual plane was 100% developed for carburated vehicles to increase vacuum signal to the carb......the is NO other reason to use a dual plane intake. Some claim that the extra runner length is beneficial, but only 4 cylinders get this....stare at a dual plane and see for yourself, four runners are longer. Having a single plane makes sure that all 8 cylinders receive the same amount of fuel as best as the mechanical aspects of the engine allow. The K5 Blazer we did had a Blueprint 355 with a high rise dual plane and four plugs looked a little different than the others.......not bad enough to make me want to change the intake....but if it were mine personally, I would have changed it out before the EFI was ever installed. EFI does not require a signal to work....therefore a dual plane becomes obsolete.

On a Big Block...the only single plane inatke that fits under a stock hood is the Torker 2O.....it is not an ideal intake, but for up to 480 horse or so, it is not a restriction. I recommend blending the runner dividers and port matching.

There it is. Others will chime in on their experiences as well.....this is just what I know from observing the field and installing two units. I would use another.

Jebby

 

I have a non-quadrajet style Sniper with timing control on a GMPP 350 H.O. and agree with Jebby in regards to Holley's tech support. It's trash, and that's even if you can get them on the phone. If I had to buy again I would buy from EFISystemPro. Chris even answered a few of my questions despite not purchasing my Sniper from him. I learned more about how to tune my Sniper by asking questions here and on the Holley forums, which is also another good resource. The most important thing to keep in mind is that you will have to tune your Sniper to work with your engine. It's a "self adjusting" system but not a "self-tuning" system as advertised, and the base tunes that come with the software are not great. If you have any other questions, I'd be happy to answer them.

 

Yes, the tuning input by you is the median.....and the system has a "window" of operation......you can move the median but not the window.

Jebby

 

I had a Sniper EFI Holley 4150 style "carb". It worked great on my 327 with an old tarantula style low rise single plane. I transferred it to a 396 with a lw rise dual plane and it was running rich on one bank and lean on the other. Never got it straightened out. When I went to remove it there was standing gas on the valves and in the manifold...Puddles of fuel. Get a Low rise aluminum single plane and it should work for youir daughter.

Buy the EFI system from https://www.efisystempro.com/ They actually have customer service and care what your doing

 

Thank you all so much,
I'm going to go with the quadrajet model so I can you the spreadbore intake that came off a 70 454. I know it's cast iron but that ok with me. That's what this efi was designed for. Really really appreciate Jebby for steering me to the right place to buy.. and will definately go with the distributor and there's a part the allows me to forgo the return line. Hope that's a good plan.

Jim

 

Jim the EFi Looks like a spreadbore so you can use it on aspreadbore intake, but its not designed to be used on a dual plane intake. All REal EFI intakes are essentially single plane intakes. Hope it works for you...good luck

 

I've filled out my profile on EFISystems pro and will be talking to the representative on Monday and determine what is the best fit for me. Will keep everyone posted. Thanks again for the recommendation for EFISystems..

Jim

 

I know this is a few days old, but I've installed 3 of these now, and they're amazing. As said before, if you can, go with timing control, but I haven't used it on 2 of them, and I've been very happy. The driveability and cold starts alone make the swap worth it.

 

Can you tell me what other components you installed? Distributer,Fuel tank?
Thanks

 

Sure. I put in an HEI distributor with a cable tach drive, and it was not MSD. I didn't do anything with the fuel tank. I ran the rubber fuel line from the unit back to the fuel pump, and then into the tank. I used the existing metal return line.

 

Go with the retrofit intank pump no return needed I hated hearing the external fuel pump all the time ! .Also the complete Hyperspark ignition system ..I tried the progressive linkage but it did not work well with my AIR Gap manifold ..Engine likes all four injectors spraying fuel even at idle ..
After the self tuning she runs sweet ! Starts quick..Go with EFI System Pro and read the Holley Sniper forum lots of useful info on there...Be prepared to spend more than you think ,just buying the EFI is not enough you need the other components to
get the full benefits of the system...

 

I had sniper efi on my ls5. It never ran right. Went for a holley dp instead for trouble free driving.
Im sure many people using sniper and got great experience but don’t forget that with cpu you’re adding more potential problems.. just my two cent