Great White Shark Story
Fuel Injecting the '73, or how I spent my summer
Memorial Day weekend, Kim and I went racing in Tucson. While doing back-to-back drag racing and autocrosses in 110 degree heat, we lost the oil pump and fried the motor. I had been talking about getting rid of carburetors and going to fuel injection for quite some time and this incident finally gave me the incentive to make the change. I had been researching a variety of systems and decided to use TPIS out of Minneapolis. I had work done by these folks years ago when we lived in the Midwest and had always been satisfied with their expertise.
[Fuel system mounted under frame rail]
I pulled the 383 and sent it off to the machine shop (Doug Anderson at Automotive Machine Services) and bought a used L-98 out of a '89 Corvette. It came set up for Mass Air Flow (MAF) and I decided to convert it to Speed Density as used on 90 to 93 Corvettes. The reason is it's simpler and easier to set up than the MAF. I got a harness, computer and chip from TPIS and they programmed it based on the characteristics of my car. Their harness was extremely easy to connect and their technical support is the best I've ever dealt with.
[F-I Motor installed, front view]
The conversion has four major areas; mechanical installation, fuel system, electrical, and air intake. Mechanical consisted of taking parts and accessories off of one motor and putting it on the other. The biggest difficulty was finding the right flywheel to go on the L-98 because it originally came out of an automatic. The folks at Findanza took my drive-train specs and came up with the right Aluminum flywheel. It had to mate up with a Tremac 5-speed, Centerforce clutch, and a GM bellhousing. It went together flawlessly.
[Driver's side shows Lokar throttle cable system]
The fuel system was a real challenge. The Fuel Injection system requires a high pressure feed and return, both 3/8" in diameter. The '73 has a 3/8" fuel line but a very small return. I ended up running steel braided fuel line back to the tank along side the existing steel line. I dropped the tank expecting to have to take it somewhere to have a 3/8" return tube welded in but to my surprise, where the carbon canister vent line connects to a separator mounted on the tank, it already had a 3/8" tube feed in at the top.
I installed a Bosch external fuel pump that I got from TPIS and a Fram 10 micron canister filter. I wired it back to the TPIS supplied fuel pump relay and I had a functioning fuel system.
[Passenger side shows MSD box and air intake]
The electrical was straight forward. Because the car is too old for emissions, I bought what TPIS calls a Street Rod harness. It has all the necessary operating connections, but no EGR and the like. Every connector was clearly marked and the conversion uses all standard GM sensors. We ended up mounting the computer and relays under the passenger side dash. The toughest part was removing the wiring that I had done to install an electric fan and the old low pressure electric fuel pump. The fans and fuel pump relays are now controlled through the computer. I took my headers to a muffler shop and had O2 sensor bungs welded into the collector. Because I have long tube headers, a heated O2 sensor was required. A GM small cap divorced coil distributor was used and the guys at TPIS even helped me wire in the MSD 6-AL. A new set of MSD wires was installed and the electrical was done.
[Heated O2 sensor in header collector]
The last system was air to the intake. The short coming of the GM Tuned Port Injection is the small plenum and long intake runners. A big breathing engine runs out of steam around 5000 RPM's. In order to improve the situation, I added a TPIS airfoil and, I hate to admit it, put on a large 4" diameter piping system from the Rice-Rocket store. I moved the Manifold Air Temperature (MAT) from under the plenum to the duct just behind the air cleaner.
Finally the Great White Shark was ready to start. It cranked for about 10 seconds while the air cleared out of the fuel lines and …Ta Da…it started like…a fuel injected car. I set my base timing and drove off into the sunset.
[The '73 back under power]
The saga isn't over yet…the 383 is back from the machine shop with Keith Black flat tops, a CompCams roller cam, Dart aluminum heads and a big breathing Ram air system on order. After SWI, the big motor is going to replace the L-98 and watch out. As they said in Tucson when Kim was drag-racing…"she may be little, but she's got 400 horse power"…well, make that closer to 500 now!
[The final words]