I am considering adding fuel injection to my 73. Has anybody had any experience doing this?

I was thinking about using one of the following:

The Easy EFI by FAST
The Edlebrock system
The Holley Commander system

Any help would be great.

Thanks,

 

I am running a http://www.mass-floefi.com/mass-flo.html system on mine. Fuel injection in my opinion is the way to go. Instant starts better idling and mid range. Much more efficient. Driveability is much better. You can't beat a modern FI system. I did have to modify my fuel system and went a little over on that but it all works very well.

 

I have been looking into these also. If you haven't take a look at the powerjection III. The only problem im running into is putting in that electric pump. You must mount it by the tank and run wires/fuel lines and have some sort of safty system to shut it down just in case. I put in a new fuel line for my carb setup and it's not fun trying to put in a new line with fuel dripping all over you.

 

 

I am running a TBI system from a Chevy P/U. There is no question that FI is the way to go.
If I had it to do over again I would not use the system I have. Both the Edelbrock and Holley are good products. I would choose a system that controls both fuel and ignition.

 

well, somebody has to stimulate our economy
i like the new Dodge Challenger, and, i would not put a carb on it
But, i wouldnt put EFI on a carb car either.
http://community-2.webtv.net/mattgru/EFIMPG

 

Matt, I have to disagree, as for the primary reasons that Lars has posted about, guys are having a very rough time getting any carb to run right for various engines these daze, and the very first thing to suffer is the fuel economy, and yes, if it's fought long and hard enough it's possible to get a QJet to respond, maybe.....but when the last one built was some 20 years ago, tossing a kit just don't seem to do it, and I ran into that situation over 20 years ago, so to change the intake to something like a AFB, square bore and buy one from Edel is the only serious choice for a street machine to get any economy out of, a Holley is for drag racing and shows....

I know my bone stock L48 rebuilt mild street engine with Muncie and 336 went from a tops of 14 mpg to 24 mpg when adding the stock TPI to it and nothing else to greatly affect economy, I did have the serp drive in place before the TPI though.....

my little <400 hp 355 roller engine now gets about 20-22 maybe....with overdrive, still the same essential setup...
but larger injectors, and more agressive cam....

two things to get a carb to respond, a wide band O2 sensor, and a good parts kit, and a good carb to play with...all fine,....200 bux + for the O2 sensor, now get into the carb and kits, and pray the carb you got has not been all butchered up and/or need the throttle plate reworked, at some point a FI setup is just plain simpler, and easier....and not all THAT much more money....

plus the facts are these daze that FI off a junkyard vehicle is much cheeeeeper than they were some years ago....even with programming, assuming you stick with a stock computer....

then we get into the fuels available today, and complaints of what they do to antiquated fuel systems....

having said all that, I am using a nice clean old Carter built Qjet on a camper I am rebuilding, because it hung on my shop wall for some 20+ years gathering dust, the Qj that was on it was toast....

 

Here is my Tuned Port "primer" They are cheap now, and fairly easy to install. I have 2 and really like them. You could also go LT1 pretty cheap, but you need a C4 engine brackets (or aftermarket) to make it fit.
*************
You have a unit
First you have to determine whether you want mass air flow or speed density. The C3 is more conducive to speed-density due to space issues. Mass-air flow is easier to make engine changes without PROM changes. If you are technically proficient enough to make a Camaro harness work they can be bought for $100 or less. I have been told that you can also use a 3.1 Corsica or Cavailier harness with a little work, it uses the same 7730 Speed-Density ECM. Aftermarket harnesses range from about $300 for Painless to $500 for Howell to $700 for Street and Performance. Howell makes a great harness, but for a Tuned Port they do not make one that will control the converter lockup on a 200R4/700R4/4L60 transmission. If you are running a manual or non-overdrive-automatic transmission I highly recommend them. I have heard great things about Street and Performance harness, but do not have first hand experience with them. I also have a Fuel Injection Specialties (FIS) harness and it is OK. The ECM can be had used for $10-50. A good external fuel pump will cost at least $100. I use an 88 Ford Truck external pump, $114 from CarQuest, made in Texas by Airtech (also avialable at O'Reileys). If you have a 78-82 you can use your fuel tank with an 82 sending unit and a TPI pump. 68-77 can also use a modified tank or Rock Valley makes a tank for these cars with a baffle and a GM internal fuel pump. Stock 82 tanks do not have a baffle contrary to popular belief. An aftermarket PROM with VATS and Emissions codes removed will be $100-200 depending on source and complexity. You will have to add an oxygen sensor to your exhaust, $20 for the sensor, $5 for the weld-in bung, and say $25 for an exhaust shop to weld it in if you can’t. Some harnesses use VSS and some do not. An auxiliary VSS sensor is around $75. I recommend using VSS to get better drivability. To install a TPI I say figure at least $800 plus the TPI unit and whatever repairs are necessary to bring it up to useable status. I have TPI/700R4 in my 69 Corvette (Howell harness) and an 83 Pickup (FIS harness) and I love it. Starts good, great torque, good fuel mileage, easy to swap onto stock engines (although both of mine are complete engines out of 90/91 ‘Vettes).

Differences in years
All Corvette TPI intake manifolds work with the older (through 86) iron heads and the factory aluminum heads through 91. F-body TPI intakes use the upright center bolts on 87-92 and thus fit all 87-95 iron heads (non LT1). Either can be swapped to fit the other with some drilling. F-body has the fuel lines come out on the drivers side and has a central port for EGR. Corvette has fuel lines that come out on the passenger side and has an external port for EGR. Corvette fuel rails fit F-body intakes and vise-versa. The runners are all the same through the years, but the LH runner has a hole for a 9th injector in the 85-88 runners. This can be plugged off if you get a nice LH runner and don’t want the 9th injector or decide to run speed-density. The plenums all physically interchange, but 90-92 have an extra vacuum port for the MAP sensor used with the speed-density computers and wiring. 89 is an odd year, it is mass-air flow but without the 9th injector. 89 up throttle bodies can be used on all years, but a 85-88 throttle body requires a ½” hole be drilled in the front of a 89-92 Plenum for idle air. 89-92 Throttle bodies have a more desirable cable attachment. The cable attaches around a circular linkage which has a smoother actuation than the straight linkage on the 85-88. The Corvettes have an aluminum plenum extension over the distributor, the F-body extensions are plastic. The Corvettes use an HEI coil-in-cap distributor for 85-91 (Delco 1103680). 85-86 F-body also used a big-cap distributor. 87-92 F-Body used a small cap distributor with an external coil (Delco 1103479). This same distributor is used in the 87-95 5.0/5.7/7.4 TBI injected trucks and pre-LT1 B-body. The F-body intake gets it's exhaust for EGR from the center passages in the heads like most SB Chevys. A Corvette intake gets it's EGR exhaust from the RH exhaust manifold/header through a flex-tube to an opening near the distributor-no center passages in the intake. If you are required to keep EGR and you have a Corvette intake, I recommend getting the C4 exhaust manifolds. They are like mini-headers, and have a 2 1/2" outlet. I have them on my 69 and like them.

As far as a throttle cable to use, on my Vette, I used a TPI Corvette cable, 1990 I think (now discontinued from GM) but you have to cut the end off inside the car and use a hood-release-cable end (Corvette Central 342138 "cable stop") to get it the correct cable length (the housing is OK). You must use a cable from the type car your throttle body came from if you want to have a chance of not cutting it. Again, 85-88 use a straight pull, while 89-92 have a circular attachment for more smooth actuation and so the inner cable is longer. On my 83 truck I used a TPI F-Body cable and it was OK, but I had to coil it up into a loop in the engine compartment because the housing was so long. I also TPI'd a 72 Chevy truck and used a 90 350 TBI truck cable for it. It was 1/2" short outside if anything, but I was pretty pleased with it all told-I didn't have to shorten it. In a Vette it might be about right. In all vehicles I've done you need a die grinder to square the firewall hole off a bit. All vehicles I've done used the late throttle-body.

I would look into a TPI. They start immediately in winter, have great vacuum, and will get great mileage. I can open the headlights and the wiper door at the same time with no hesitation at all-solid wooomp. With 3.70 gears (and a 700R4 overdrive) I get 18mpg city and 22+ highway. With 3.55 or 3.36 it would be even better. You can probably find a used Corvette TPI engine for $1000 and with an $800 harness/computer/fuel pump you would be set. On a 78-82 you can use the stock fuel tank with an 82 sending unit and TPI pump and be in better shape than 68-77 with an external pump. With the Vette TPI you would have aluminum heads that would remove weight. Even with an F-body iron-head TPI 350 it will be less weight than a stock intake. It will bolt up to everything in your car, use stock accessories, use your transmission, and the visual appeal is awesome. Don't be afraid of fuel injection, it really works.

As far as websites see:
www.corvettefaq.com for conversions or more TPI info at www.fuelinjection.com also www.jagsthatrun.com for misc hard to find conversion parts and info.

LT1
Not to get too deep into the differences in LT1s, there are basically 3 variations. There is the C4 ('92-96) and an F-body ('93-97) version which are 5.7L and have aluminum heads. There is a B-body ('94-96) which is 5.7L with iron heads that actually flow better than stock aluminum heads. There is also a 4.3L B-body (L99) version that you want to stay away from. There is an LT4 in '96 that is an upgraded LT1. All are dimensionally the same as far as bolt-ons. Corvette engines have 4-bolt mains, all others have 2-bolt. All are cast iron blocks. An LT1 is a very similar installation to a TPI. As far as the mechanical installation, the 700R4 and 4L60E transmissions are the same (same length, same basic dimension, mounting, yoke, etc.). You have to have a computer to run a 4L60E which you will have for the engine anyway. As far as the engine, an LT1 will bolt in and can use the same exhaust although you may want to use C4 LT1 manifolds to get true 2 1/2" outlets. The biggest difference between a TPI and an LT1 installation is accessories. TPI can use stock C3 accessories. LT1 has to use LT1 accessories and really needs C4 LT1 accessories. Both F-body and B-body put the a/c compressor low on the passenger side. This interferes with the frame and the right motor mount. You have to use electric fans on an LT1, there are no provisions for a mechanical fan (B-body has an optional one, but it is offset and won't work in a C3). The other difference is in air intake, most LT1s are mass air flow. Again, it is difficult to locate the MAF sensor in a C3. You are better to have it set up for speed-density. In a '78-'82 C3 you could still use an '82 sending unit but an LT1 fuel pump instead. You will want to stay with programming for an OBD1 (pre-'96) style setup, without multiple oxygen sensors. '96-'97 OBD2 engines are fine, you just don't use all the sensors. LT1 requires a custom radiator because of how the hoses run. There are differences in the Optispark, later is better and if you swap to a later cam you can add the later vented Optispark setup. The water pumps are bad to fail and wet the Optispark, so always replace the water pump when you do a swap. LT1s have better top end power that TPIs, but all things considered I'd rather stay with TPI for a cruiser or mild build-I just like the look and the low end torque. If you want more power, LT1 is better; or just step up to an LSx.

 

try a search on this forum you will find that this has been talked about a lot .my vote is the fast efi

 

I have the Edelbrock EFI on one of my cars (not a Vette). It's mounted on a GM Performance 350HO. It's an excellent system...trouble free and very smooth running.

My only complaints...the electric fuel pump is somewhat loud (not unusual for any aftermarket electric unit), and you'll probably have some clearance issues with a C3 hood. Outside of that, it's a great.

 

 

I would love to have EFI...but there's just no way I can justify the expense vs. the fuel savings--AND it would lower the value of my 'stock' vehicle. Still, it would be nice.