conway62

Has anyone installed this EFI system? Looking to convert my 71 BB to EFI. I read some threads on the F.A.S.T system and it seems everyone is happy with it. The video I saw on the Atomic system looks pretty good also. Id like to hear some feedback from anyone who has installed one on a Vette.

Thanks
Ron

kdlp

I'm with Ron except I'm thinking about my 400 hp small block...anyone?

kdlp

Vette5.5

Don't think I'd do it, as really not seeing much advantage of throttle body injection, over a well tuned carb. If getting into that kind of money, probably hunt down a low milage LS motor, and go that route. GM Performance, actually sells an LS retrofit computer, with full wiring harness, drive by wire gas pedal, ext for about $1K. They also sell computers for the latest 6 speed auto tranny's. Something to think about.

Shark Racer

It's not *quite* throttle body but not quite port. Sort of a middle ground.

TBI had low pressure, this has the same or higher pressure than a typical port injection setup. So there *will* be better fuel atomization vs carb or TBI.

The major advantage is in closed loop self-calibration - your metering will constantly adjust for any environmental condition.

There are definitely cheaper ways to do it - but this is probably the lowest effort. (and all the others - EZ EFI, Powerjection III, Holley's kit...)

conway62

What have people done with the fuel lines? Are the factory lines ok to use or does a new high pressure feed and return line have to be installed. If so, where have folks run the lines. My 71 has them routed on top of the frame between the body and the frame. Cant imagine trying to run them there. What about the gas tank? Is it sufficiant for fuel injection?

- Ron

aussiejohn

Ron,

The MSD kit comes with a length of flexible high pressure fuel line, but I can't see why you cannot use the existing steel line. Both factory and MSD are 3/8" lines and this is ample for up to 600 hp. You just need two small lengths of HP hose between the tank and the pump and the pump and the factory steel line. Plus another length from the engine end of the steel line to the Atomic FI unit. Just make sure that the clamping is good.

You don't even need the factory steel return line as the Atomic unit is a returnless system whereby the fuel pump is electronically controlled in order to vary the fuel pressure. Remember that this system is designed to go on any engine in any body/chassis, whether or not it has a factory steel fuel line fitted.

The good part about the Atomic unit is that a lot of the wiring that would be found on other FI units is kept inside the Atomic throttle body. Plus the fuel rails are internal, again unlike most of the opposition. From what I saw at the SEMA Show last November, this really is a "plug & play" proposition. Just connect the fuel line, one 12v. wire and weld a bung into the exhaust system for the oxygen sensor and connect it.

Connect the throttle linkage and you're done, basically. Go buy one and document the fitting for us.

Regards from Down Under.

aussiejohn

conway62

Im still confused about the need for a return line. Their instructions say if in a warm climate (above 80 degrees most of the time) then a return line is needed. Im in Florida so this may be an issue. It gets even more epensive if a return line is needed. Other folks posted on here that you can use the factory steel line also. However their instructions say to never use a steel line. So Im a bit confused. Any additional imput from anyone would be greatly appreciated.

BrooksCJ

Conway62,

I was looking through the MSD forum page and this is a post from the MSD Tech:
"Steel lines cannot be used with a PWM (returnless) system due to the "water hammering" effect created by the pulsing of the fuel pump. The flexable fuel hose will absorb this effect."

http://www.atomicefi.com/forum.aspx?...&f=12884901886

I know the instructions say the same thing for the return style setup, but it appears to be a typo. Since the fuel pump won't pulse during the return style setup, using your 3/8 steel line for the return shouldn't be an issue.

I live in Florida too and when I used the points chart they have in the instructions, I received a 4. I think I'm going to trying to run the returnless setup with the fuel pump outside the tank and see what happens. If that doesn't work, then I'll run a return line.

I hope this answers your question.

C.J.

Vette5.5

The return lines really a fuel temperature thing. Whole idea being, there's always some fuel moving through the lines, looping back to the tank. Usually, just a small orfice fitting, so not enough to affect pressure.

Tim H

I think there is quit a bit of difference in changing out your carb for this EFI unit in half a day verses changing out a whole engine and wiring?
That is comparable to rebuilding your engine every time you change the oil!

I'll just wait for the Chinese version to come out for $500 instead of $2000 MSD is charging.

Shark Racer

I'll second this and add that as much as I'd love to change to an LS motor, every time I start to get serious I get ringing thoughts in the back of my head about lifting the hood and not seeing something that looks like what I've been seeing for the last 13 years.

Garys 68

I think you might ask why convert to what's basically a tbi over a carb.
Milage will improve a little, emissions will almost certainly decrease, top end hp will be about the same, reliability would be about the same.

conway62

I talked with the folks at MSD. They told me that in one of thier test vehicles running a returnless system on a trip between Texas and Arizona in hot weather, they experienced fuel pump issues. He recommended either running a return line or mounting the pump in the tank. Also, how do we address the issue of sucking air into the line during a low fuel situation and also reduce sloshing effect below 1/4 of a tank?

So, I have a few questions.

1. Can our early C3 tanks be easily modded for an internal pump?

2. Is there a later year C3 or perhaps C4 tank that will fit that is already set up for this?

3. Can a fuel expansion tank be used to handle the fuel slosh or low fuel issue so the pump doesnt suck air etc.

dembo

After my ordeal with the powerjection 3 returnless, where fuel pressure builds up to +100 psi after shutdown, not even during hot weather, after the car idled for 5 mins with a cold start I'm hesitative towards these systems and sooo happy I went back to carb, to bad it was a costly lesson
Nick

7t2vette

1: Easily done, no problem. There are several options available, after considering all the options, I decided on the Rock Valley fuel pump module.

2: Not sure. I think the later C3 tanks had the pickup mounted through a hole in the top of the tank, and the 82 might even have had an in tank pump, but again, I am not sure. Either way, those tanks were not baffled to prevent the pickup going dry.

3: You can go with a surge tank setup, but I decided to keep things simple instead. I thought why make things more complicated than they need to be!

This is what I did for my FAST EZ-EFI system. I've posted this several times before, but I will post it again in case you haven't seen it.

I went with an SS internal fuel pump/sump module kit from Rock Valley, for lower noise levels, a cooler running pump, and because of the design that traps fuel around the pickup. It cost $375 including the Walbro 255 lt/hr pump, and is very well made. It is made entirely of stainless steel, and it is made to fit into the stock tank. If my tank wasn't basically brand new, I would have went with the complete Rock Valley SS tank and fuel pump/sump. I had my local race shop weld it in my tank for me, then I custom bent SS hardlines for it. I then painted the tank.

































Here is my tank installed in the car:



No problems with this set up after 2 years of use. The pickup has never gone dry under any situation, and I have ran it almost completely empty a few times.

Hope this helps

conway62

Looks like an awesome install but also looks expensive. Not sure I want to get into all that fab work. F.A.S.T has a universal retrofit inside the tank setup. Looks pretty good. Would just have to drill an ll/16th hold in the top of the tank for the wiring. 150.00 includes the pump and all the fittings needed. Then again it might just be worth connecting everything up to the OEM supply line and mounting everything externally. Still trying to figure out whats the best solution for quality and price.

7t2vette

As I posted, the $375 Rock Valley fuel pump module is made entirely of SS and includes the Walbro 255 lt/hr pump. I paid the shop $50 to weld it in place. It is a high quality piece, and worth every penny. Short of either baffling my tank, or having a custom baffled tank fabricated, I felt it was the best solution to what I wanted.....no uncovering of the fuel pickup under any circumstances. The rest of the fabrication that I did isn't necessary, it's just what I chose to do.

The FAST kit you mentioned doesn't do anything to prevent the pickup from sucking air, which is what I thought you were concerned with.

There are other less expensive methods you can use, such as:



http://www.tanksinc.com/index.cfm/pa...prod/prd84.htm

OR



http://www.vetteworksonline.com/cata...f283f31139db4a

Brooklinite

Geez Bruce, even your gas tank is pretty!

airtime

i am thinking of installing an ez efi on my bbc 71 vette. going to use the factory return line and factory supply line. and go external pump. i did this on my 67 camaro (except i ran a new fuel line out of aluminum and used factory fuel line as the return. 67 model only had one fuel line) and have not had any fuel starvation issues in 12 years. hope the corvette will be the same. i am looking at the holley hp efi with the 900 cfm tbi. good for 550 to 600 hp. with the holley hp you can controll timing and nos or a turbo at a later date if you wish, plus its a ez self tuning model also. if you get the basic holley avenger ecu it comes with a hand held unit to tune engine with.

gdh

So what mpg improvement is achieved by going from a carb that was tuned using an a/f meter keeping the same trans. Most here seem to have added f.i. and a new 5 sp trans. and then report back their mileage increases. I well understand the benefits in addition to mpg that f.i. offers but would just like to read some first hand C3er experience sort of like Wayne (MotorHead) did when he swapped in his 5sp/