Holley EFI special- today only
 

Just saw this- today only

Dang... hate I missed this. Maybe catch a holiday sale.

Check with EFI Systems Pro

https://www.efisystempro.com

He's a Holley dealer and runs specials occasionally and with the holidays coming up I'd expect to see more.

In fact, we bought both of our Holley Super Sniper Stealth 8 injector units from Chris at EFI Pro and he wasn't running any specials at the time, but knocked $200 off anyway. Great guy to deal with.

I've been looking at the sniper stealth kit for a chevy that has a street / strip 375-400hp sbc engine. Currently running a Holley 4150. It's always been extremely cold blooded & while it performs great, its street manners are less than desirable. some hesitations and cold start stalls that I was never able to completely get rid of. It would be awesome to have something that would run better cold & self tune. The car already has an in tank GM fuel pump, so I have figured out the Holley pump I would use, but not completely clear if I have to have the full pressure regulator up on the firewall, or if I can mount it closer to the fuel tank. The car has no return line and bending one up to look factory might be a bit of a pain, but surely not impossible.

Can't seem to find much on the pros cons of where the regulator should be located & why. Maybe on a smaller engine like this its not a big deal?

Good news I stumbled on is it currently has an MSD distributer & ignition system that is compatible with the sniper kit to take control of all the timing. That is really cool & a pleasant surprise.

68rag - the Sniper has a regulator built into the throttle body. You do not need an external regulator. You will need a high pressure fuel pump and a return line to the tank.

if you have an electric choke, try switching it over to a manual cable-operated choke. i did so on an old big block chevy plow truck. once i got the fast idle screw set up right, it made a world of difference.

functioning heat riser valve makes a big difference in cold startup performance too.

The Sniper "Stealths" do not have a built in regulator.

I assume there was no way to do that and still maintain the Stealth appearance of a carburator, so you'll need a regulator in the system. No big deal.

You can mount it anywhere you want, back at the tank or up near the Sniper unit. I will say though that it's recommended as close to the Sniper unit as you can, with a full length return. That will give you the most accurate fuel pressure for the unit to operate, among other reasons.

It does work with a regulator setup at the tank with a very short return if that's really the way you want to go.

To add, at the mild 375-400hp level the 4 injector 4150 Stealth will probably do everything you're looking for with it's self tune capability, better cold starts etc....and have room to grow power wise. Usually when you get up into some of the more rowdy engines and bigger HP, the self tuning will only get you so far, and will generally require some lap top tuning to really dial it in.

Yes if you want to control timing, the Sniper Stealth will work with a current MSD distributor and box. You just have to lock out the distributor, wire it per instructions, and off you go. Most buyers opt for the dual sinc distributor setup from Holley.

I see they have what should be a direct fit fuel pump. not very expensive either.
I was just looking at the manual that showed I needed an external regulator, but Might have been the wrong manual. I'll take a peek at that. I'll probably remove the original line as a template & see if I can bend up a matching return line the piggy back on the routing. Also need to weld in a A/F sensor bung & I have the exhaust system ceramic coated already. They guy who did that for me is no longer in business, so I'll have to find somebody to redo that mid pipe.

It does have an electric choke, but it always has some hesitations at part throttle. I messed with timing curves, power valves & jets & never got it completely cured.
Just thought it would be cool to unlock the ability to fine tune it from the drivers seat. :)

When I built this car, I tried to make the drive train look factory. Has A/C & all the brackets that make it look like a factory 305. But, its a built ZZ3 based 350. I bought the MSD HEI lookalike so I could run an oem style cap & wire retainer. It has the lockout features, but lacks the adjustable spark rotor. I think I can get around that though by using an adjustable "fixed" vacuum advance device. it locks the pickup coil, but with that I could adjust the distributor to best line up the rotor and cap, then tweak the pickup adjustment to get it back to the correct fixed location. Which I believe is 45 degrees advanced & the system corrects everything from there. I did see the adjustment however is made setting it by using 15 degrees as the reference point. But mechanically it looks like the pickup is supposed to be at 45 degrees from TDC. This makes sense to me as then the system knows exactly how many degrees to retard from 45 & likely never go past 32 or 34 total on this engine.

Does this system let you specify an initial timing as well? This engine seem to like 32 ish total, but somewhere around 10 degrees is where it starts the best. Anything more & I get some preignition issues when its hot. The MSD distributor let me dial that in very nicely.

Yes you can specify cranking timing and idle timing separately. Much more tunable than a mechanical setup.

You sound a lot like me with the stock appearance thing. That's exactly why I went with the Stealth unit on my Chevelle. I even went as far as to make factory steel lines with the brass block, running down to a mechanical fuel pump. It's all "dummy" stuff that has no fuel in it. I ran the main fuel line hidden into the back of the Stealth unit.
With the air cleaner on it looks like a stock carb with stock lines and a mechanical fuel pump.

I was leaning towards the super stealth only because my air clean drops down a lot to clear the hood insulation. It has notches in the front & back for the conventional bowls, so I was hoping the super stealth would fit under it with no mods. But maybe I would be better with the regular sniper & modifying the air cleaner setup. Hmmmm

Yep, I'll post some pics. Its not stock, but built it so at first glance it looks like it could have been. Sanderson shorty headers stand out a little but everything is so tight in this car you don't see them at first.

A couple pics. The top engine pic is recent, bottom pic is now 13 years old! What I just noticed is how dull/oxidized all the aluminum stuff has gotten. I could tell, but the pic really makes it stand out. Never noticed it has changed that much.

I have the factory 2bbl air cleaner. I was planning on swapping out the bottom with the aftermarket chevy thats on there now, but never go to that. that factory setup has a very restrictive snorkel on it. ThoughIT would be cool to add a W72 snorkel to it, but for some reason I never pursued it & just lived with Chevy PP lid.

On the second pic you can see the factory fuel line above the brakes booster. Plan would be to remove it all the way back to the tank & see if I can bend up a tandem line.

https://forums.maxperformanceinc.com...1&d=1613322126

https://forums.maxperformanceinc.com...1&d=1613322126

You spent a lot of time on that Spyder :thumbup:

I had 3 of those over the years. My wife enjoyed driving them. Fun nimble cars.

The stealth will fit most any factory air cleaner that was originally equipped with a holley, or made for a holley.

I have the factory cowl induction air cleaner over my Sniper and works great, and dad uses an L88 air cleaner assembly that also fit the Sniper perfectly.

I had a Spyder,1977 and yellow, like that in high school. I loved that car. One day I will find another one. That looks great. Mine was manual steering and no A/C. I will probably put an EFI on my Firebird in the future.

Slightly off topic, but I just noticed that Holley offers a Q-Jet style Sniper. They claim its about the same dimensions as a factory carb. Does anyone know or have first hand experience with this?

I'd like to run it under a shaker, but I can't modify the shaker base in any way, shape, or form.

Thats what I had in high school. Prior to me purchasing mine in 1985, it was only 8 years old & getting pretty rusty form the Wisconsin Winters. Looked good, but door seams were already letting go on the bottoms. Lots of great memories. Dropped a tired 350 in with a cam, intake & carb to replace the anemic 140hp 305 & the fun factor went way up. Then started looking for one 20 years later & it was nearly impossible to find a nice one. By chance of fate / luck I found one out of Florida. Low miles & ron solid. All the plastic & rubber was dried up, but completely rust free. So I started a 3 year restoration on it.
You almost had to own one of these cars to have any interest in them. Kind of a cult thing I suppose. Extremely hard to find nice used & NOS parts for. The car was easy to restore, but getting parts was another story. I am guessing thats not getting any easier as whats out there ends up in a few more of these H bodies. :) Probably near the bottom on the collectibility scale, but thats not why I wanted it. :p

I have another set of wheels I run as well as the rallies in the pic.

https://forums.maxperformanceinc.com...1&d=1613390660

First, I would probably recommend EFI systempros because they appear to offer the best overall support and remote tuning through Mad-Science: https://mad-sciencemotorsports.com/

Second, if you are considering either a Sniper Stealth, Super Sniper or Sniper X-flow. I would take a long hard look at the Terminator Stealth X. It looks like it went up a bit in price recently but has a lot of advantages that the average person would actually use while offering increased RFI resistance: https://www.efisystempro.com/termina...1001-thru-1016

Thinking I am going to try the sniper EFI, or sniper stealth. I really don't need all the extras the terminator series offers.

Aside from appearance, is the only real difference that the stealth requires the external regulator & the regular sniper is internal? I guess I can go either way. buying a different air filter base is not a big deal. I am really, really tight for height though. I was trying to find the height of these units. specs say 3.28" but not sure if thats overall height, or bottom mounting surface to air cleaner resting surface.

my current carb is about that same measurement from base to air cleaner mounting surface.

here is a link to each if anyone want to take a look.

https://www.holley.com/products/fuel.../parts/550-510

https://www.holley.com/products/fuel.../parts/550-870

I don't know about the one that looks like a thermoquad, I've never had one of those in my hands, but the Stealth that I use ended up being exactly .200" taller at the air cleaner flange than the 4150 Holley 950HP carb that it replaced.

I looked at the Q-Jet style. It's supposed to work wth any factory deal...Ram Air, shakers and all. Don't know if that's a fact or not. They say it supports 500 HP and flows 715 CFM. Those specs were a little low for being a Q-Jet replacement it seems. Don't they all flow at least 750 CFM, some maybe 850 CFM? They can support well over 500 HP. I believe the secondary plates are smaller than on the carb. I'd like to run it for the ignition control, but my motor is a little bit bigger than they specify, and runs really good with the SD Q-Jet on it.

I think the only thing I liked about the square looking unit was the built in regulator. Really didn't want to mount a regulator & filter on the firewall, but maybe I can come up with something thats not too noticeable.

I do think the stealth unit is a little better looking though. still looks like a carb & maybe not out of place.

On the Pontiacs I mount the regulator where the mechanical fuel pump used to be. Not only is it hidden there, especially with power steering, but I can maintain the factory routing of the fuel lines that way, and sometimes even bend up a steel line to the unit from the regulator to make it look factory.

The filter I'll generally hide down on the frame somewhere before it enters the regulator.

Still haven't ordered one. Leaning towards the std sniper because of the built in regulator rather than external. Otherwise I don't see much of a difference besides the looks. I really like the edelbrock pro flo 4 kit, but the manifold would not fit without a lot of changes on this sbc, otherwise thats extremely tempting.

What car you putting this EFI unit on again?

I'm glad this topic is back up. We're going with the Holley super sniper stealth 1250 in the next few weeks on my 70 GTO with the 468. I was concerned about the 72* of overlap and low vacuum, but shop has assured me that is not an issue., but what happens when opening up the dumps that is about 18" from the AFR sensors? Any questions or concerns I should be aware of?

No problems with that. We are running a pair of Super Sniper Stealth 8 injector units on both cars. I have cutouts on both cars about 18" behind the 02 on one car and 22" on the other. That's just how it worked out with the room I had.

Only thing you'll notice is the AFR immediately starts correcting the fuel table as soon as you open them up, which is what it should be doing.

Low vacuum isn't an issue either. Both cars only make about 6-7 inches at idle and the Snipers work fine.

" Only thing you'll notice is the AFR immediately starts correcting the fuel table as soon as you open them up, which is what it should be doing."

Great, and thanks.

Aside from the looks & the regulator being built in on the sniper, are there other differences? Meaning if you didn't care about the appearance or if the regulator was mounted somewhere nearby what are the other differences between the sniper & the sniper stealth? I kinda like the look of the stealth as far as blending in like a regular carb, but with the filters & regulator required it almost seems like more of a hassle? Are both models equal in every other way? Haven't found out much in that perspective yet. Or I am looking in the wrong place :)

I have some info on the 1st page of this thread with a couple pics. Fitment problem with the pro flo 4 would be the radiator hose neck, mounting locations for the PS & air conditioning brackets. the engine has the 10185063intake & allowed all the factory part to fit like it was made to fit.