Sniper EFI Quadrajet on Olds 403

[EscapeRacing]

A while back I swapped the stock Quadrajet on my 79 Trans Am with an Olds 403 to the Sniper Quadrajet EFI system. I purchased everything through Chris at EFI System Pro and I cannot say enough good things about my experience with Chris before, during, and after the purchase. I would 100% buy from him again and highly recommend him. I have not horse in this race, just think he did a good job.

With this EFI, the shaker fits fine with no modifications.

Its important to note that if your engine is not running well, EFI is not going to solve your problems. In fact, it will probably expose additional problems after the install. You really need to get your engine "house" in order as far as timing, distributor, vacuum leaks, exhaust leaks, and so on before you install an EFI or you will be disappointed.

The components I purchased were these:

Holley 550-869 Sniper Quadrajet EFI System Gold, $1199
Holley 12-304 OE-Style Fuel Tank Module 79 Firebird, $348
ESP OEMODINSTKIT Install Component Kit OE-Style Module, $46
Earl's 100187ERL 100 PSI Mechanical Fuel Pressure Gauge, $33
Earl's AT100199ERL -6 AN Male-To-Female Gauge Port Adapter, $15
Holley 12-813 Mechanical Fuel Pump Block-Off Plate, $12

Driving impressions -
I was really hesitant to swap the carb purely for nostalgia reasons, but finally made the plunge and I am really glad I did. I did not notice any material horsepower gains (and was not expecting to), but the drivability is night and day.  The car fires right up, idles smoothly, accelerates from a stop well, and is very responsive to throttle inputs. Way better than the carb ever was for me and I did have my QJet professionally rebuilt and tuned. I love the handheld "computer" that allows you to adjust the idle, fuel mixture, and other inputs on the fly. And it serves as a sudo-dashboard showing A/F ratio, timing, coolant temp, and a variety of other inputs.

Installation
This was not a one day job for me - I took my time and spread it out over a few days. Amongst maybe a few other things, you will need to drop your fuel tank, run new fuel lines, install an electronic fuel pump, wire that fuel pump the engine, remove the carb, install the EFI, install an O2 sensor, install a coolant sensor, run wires into the cabin, and tidy up the wires in the engine bay. None of this was rocket science by any stretch, but taking your time makes it look much better in the long run. If you add things like a new distributor or ignition there will be more work.

I recommend marking every single vacuum line, drawing pictures, taking pictures, whatever you need to do to make sure you know where everything came from. This will save you massive headaches later. Also, laying everything out ahead of time and having a gameplan is smart. Think about how you want to run the wiring, how you want to run the fuel lines, etc.

As far as the fuel goes, most folks likely buy a new EFI fuel tank with in tank electronic pump OR install an external pump with return lines. The Holley 12-304 OE-Style Fuel Tank Module made my life SO much better. This unit dropped into my stock tank and does not require a return line to the EFI. That does not mean its returnless, which is different. I highly recommend this unit for EFI. The one thing that took some time here is the module exits to the passenger side and our stock fuel line is on the driver side. You can either 1) skip the stock fuel lines and run new line straight along the passenger side to the engine, or 2) run a 180 degree bend and route the fuel line back to the stock lines on the driver side. That is what I did.

I installed my O2 sensor on the downpipe ahead of the cat and that seems to work fine.

Tuning was pretty easy and I am now starting to play with settings.

[Gene-73]

Great write-up, thanks for posting!  I'm seriously considering the Sniper setup so this helps.

How is the noise with the in-tank pump? I keep hearing noise is a factor with electric pumps and have been wondering how the Holley in-tank performs.
Also, the fuel line on my 73 runs on the passenger side so the 180 turn isn't an issue on the early second gens.

Were you able to install without a tech call to Holley? It seems lots of folks get hung up somewhere along the way and need support.

[EscapeRacing]

My pleasure! There is a noise when you first turn on the ignition when the electric fuel pump is priming. That lasts for about 5 seconds. I actually put the key to the on position, wait for the pump to prime, then turn on the engine. That noise does not bother me at all, but its something new that isnt there with a carb setup.

The noise I was not expecting was the "ticking" from the fuel injection itself. Its actually relatively loud and you can hear it standing outside the car. I still have not really got used to it, but its just part of the deal.

As far as how the Holley in tank pump performs, its been great. I was really not wanting to run a return line and I was not willing to go with a returnless system because I read they have issues of their own. This one fit my need and i was able to use my stock tank. Caveat - I had just put that tank in a few months prior. If I was still running the original tank, I would have been much more willing to look at an EFI tank with in-tank pump built in.

Fuel lines wont be a problem for you - it will be easier.

I was able to install everything without a call to Holley, but I did call Chris at EFI System Pro after I had it running to help me adjust my base tune, which he did. He will have you email him a data log (easy to do) and then send back a file that you in-turn load to the card that goes in the hand held unit. That was one of the main reasons I went with Chris - he is 100% there to support you so that you dont have to go to Holley. I tried a few times calling Holley before I made the purchase and it was not a great support experience.

Take your time and do the research before you jump on it. I believe you can make a QJet run extremely well if you are willing to spend the time with it, read Cliff's book, etc. I was just over the carb and made the switch.

[FormTA]

Again,  great write up! Welcome to the EFI club.  I love being able to just jump in an go any time. I started may car after winter an just went for a drive. I did nothing other than check fluids first.

[737driver]

Great write up on the Sniper! I have installed 3 of them already and an Atomic on another. I really have been quite happy with the Sniper. I did a similar install to yours with the Holley in tank pump . I would like to try out the Quadrajet Sniper the next time around for sure.
Jim

[5th T/A]

Nice write up and great pictures.

I am a little confused about the fuel return or lack of with your fuel pump. You mentioned you did not want to run a return line, yet didn’t want to run return-less? Isn’t it one way or the other? Do you have any pictures or drawings?

[5th T/A]

I also like the fact you were able to retain the stock shaker and air cleaner assembly. I notice you have an aluminum intake, but it must be the same height as the stock manifold.

[Gene-73]

I am a little confused about the fuel return or lack of with your fuel pump. You mentioned you did not want to run a return line, yet didn’t want to run return-less? Isn’t it one way or the other?

The Holley in-tank pump has the regulator and return inside the tank so the excess just flows right back in immediately. The only downside to this setup vs an external pump is that pump failure means having to drop the tank to fix.

I'm guessing that what he meant by return-less is one of those intermediate sumps that work with your existing mechanical pump.

[EscapeRacing]

I am a little confused about the fuel return or lack of with your fuel pump. You mentioned you did not want to run a return line, yet didn’t want to run return-less? Isn’t it one way or the other? Do you have any pictures or drawings?

Yeah, i wasnt sure how to articulate that. I definitely did want a return system, but didnt want to have to run a return line from the engine back to the fuel tank. Call it lazy, i guess. I also didnt want to use "no return" because I read there were a variety of issues that arise with that setup. I cannot recall exactly the issues - could have been vapor lock or something like that. Anyway, I found out about the Holley unit and that gave me the benefit of a return line system without having to run a return line. This is directly from the Holley site - they say it better than I do

"Fuel pressure is internally regulated to 58 psi eliminating the added expense and effort of purchasing and installing an external fuel pressure regulator - no separate return line is required because this module returns excess fuel right inside the tank! This 1977-81 F-body Muscle Car EFI Fuel Pump module was designed as a direct replacement for your factory pick-up and sending unit."

I also like the fact you were able to retain the stock shaker and air cleaner assembly. I notice you have an aluminum intake, but it must be the same height as the stock manifold.

Yeah, I used the Edelbrock #3711 intake manifold. My original one was looking pretty shabby and the Edelbrock shaved about 5,000 pounds off the factory one!! (kidding, obviously).

[5th T/A]

I appreciate the detailed reply.

There is a reason for all my questions. I am in the process of upgrading the original 301 on my 1980 TA with a 461 Pontiac engine I purchased from a fellow TAC member. The engine included a FAST EFI 2.0 system. I have learned a lot of research and work goes into a proper EFI installation. The FAST system can be installed with an external or internal in tank fuel pump and returnless or full return. FAST recommends using an internal fuel pump for optimal cooling, longer pump life and quieter operation. They strongly suggest a full return system saying almost all modern fuel injected cars have the fuel pump mounted in the tank and full return to allow for cooler fuel to the engine and less chance of vapor lock.

Going back 40 years ago Pontiac installed a full return on most these cars, using a 3/8” supply and a 1/4” return line, so there must have been some merit to the extra expense. With an internal pump constantly circulating fuel, your pump should stay cool and with 58 PSI of fuel pressure I would think the likelihood of vapor lock or fuel percolating would be significantly reduced, the same way a pressurized cooling system raises the boiling point of engine coolant.

A high quality in tank electric pump was included with my EFI system, but it wouldn’t fit through the sending unit opening of my original tank. On recommendations from TAC members I purchased a new fuel tank from Tanks. I liked the fact that it has a 4.7 liter sump for the pump and baffling to help prevent fuel starvation under hard cornering or acceleration. I used the original 3/8” hard lines for supply. I flared the ends using a 45 degree inverted double flare and connected to flexible lines at the tank and throttle body using adapters to -6 AN lines. For the return side I am in the process of duplicating the original 1/4” steel return lines in 3/8” steel. Duplicating all the twist and turns of the original lines is a lot of work and I chuckled when you said you didn’t want to deal with a full return. Properly plumbing the fuel system is definitely a task in itself. I also think about the dangers of a fuel leak with 50 PSI of pressure, under the right circumstances could have a flame thrower under my car. Running a carburetor this is not nearly as much of a concern because only the last few feet of the fuel system is pressurized at about 5 PSI.

My apologies for hijacking your thread. You offered lots of good input, looking forward to hearing more about your car.

[EscapeRacing]

Wow, sounds like you have an amazing build going on there! The baffling is a nice feature - I don't do any kind of hard cornering or racing or anything but its something I still would have done if I wasn't so intent on keeping my mostly new "stock" tank.

I am trying to post (re-post) different parts of my build to get some more content and pics back on the forum. I'm grateful for all the help this forum gave me over the years and excited to see it start getting content back!

[MNBob]

This was not a one day job for me - I took my time and spread it out over a few days.

Thanks for the detailed writeup.  I also installed a Sniper QJ on my Pontiac engine last year.  It took me all last summer and into the fall to install it!

Holley calls the 12-129 in tank pump I purchased "Returnless" in their product description.  What they mean is there is no external return, but the pump has a built-in regulator and returns fuel to the tank.  This model was for a carb and I had to call technical support to verify the part number to change it's internal regulator to FI when I decided to go that way.

I tried a couple of "Minnesota" cold starts in February.  The Sniper QJ handled them flawlessly.  The old QJ used to go up to about 1700 rpm on the fast idle cam and then work down.  The Sniper only went to about 1350 and then down, but ran well.


Wired (Ready for Startup)

[EscapeRacing]

Looks great!!! Love the black finish.

[Nexus]

Although I don't have the Holly system, the principals are the same and I was able to pickup the MSD setup for peanuts. This type of write up helps with basic principals and to do's which gives me ammo in knowledge for when I go to install my setup!

thank you

[Harleyfatboy]

I also have a 79 trans am.  Did you need any adapter to go from EFI to the shaker hood?  That ring you have over the EFI  looks like an adapter of some kind?  Thanks

[olds403]

I did this on a 403 using a FiTech and posted before the site crash.
The spacer i jb welded to the bottom of the air base was Spectre - SPE-4954.
Spectre efi fuel tank

I used a painless add a circuit to wire up everything and a relay bank. 
Hope that helps

[willmo]

Thank you for the excellent write up.  I'm actually in the process of doing this exact setup (also from Chris at EFI Pro) on my 78 and noticed that the fuel line came out on the passenger side and freaked out a bit until I came across your post. 

Did you use a low oil pressure sender as a safety switch for your fuel pump?  I have one for mine, but haven't started any of the wiring yet.