How a 17-Year-Old Installed a Street & Performance TPI System
There are few modifications that can be made to an engine that can give both increased performance and better fuel economy. In these days of increased gasoline prices (nearly $2.50 per gallon), fuel mileage is an important consideration for vintage trucks that owners consider their daily drivers. For many reasons, vintage pickups are becoming not just weekend toys but also weekday workers. And one of the best ways to increase both performance and mileage is with an electronic fuel-injection system.
For those who don’t want to go the chrome route, S&P can refurbish your thrashed stock TPI to make it look as if it just came off the GM shelf.
For those with Vortec heads, S&P has you covered, and in chrome no less.
Because an EFI system is a closed system, the stock tank won’t really work with it. Besides, the fuel pressure needed to operate an EFI system is greater than that of a stock system. Either way, the stock tank has to go. Rock Valley makes an aluminum tank that is equipped with an internal EFI-rated fuel pump. The new tank fits between the framerails, so it is a bolt-in proposition.
Adjusting the throttle-positioning sensor is a major step toward making your TPI work correctly. To do this easily, S&P has produced this pigtail harness. It plugs inline into the TPS sensor, and the leads are then easily hooked up to a digital voltmeter.
Wiring may be the single most daunting part of any electronic fuel system, but with the S&P wiring harness, it is as simple as making the connections. S&P has removed all of the stuff that you won’t need and left only the wires that you do.
S&P can take your old TPI speed-density computer and add a custom chip to it so that it will work with the system in your truck.
One of the leaders in bolt-on fuel-injection systems is Street & Performance. For more than 20 years, Street & Performance has helped backyard mechanics get the most out of their vehicles, and S&P does this by providing performance kits that are complete in every way. Take its TPI system for example. This system has all you need to install a proven TPI system onto your engine. S&P can provide the units themselves (or refurbish one you already have), along with the all-important wiring harness and computer mods. All of these things combine to make this not only a great install to do for the daily driver, but an easy one as well.
The ’71 GMC that will soon be equipped with the Street & Performance TPI is in dire need of some help. The truck had been sitting, but with a little cleanup and work, it will be the perfect go-getter.
To demonstrate, this install will be handled by a mechanic who is only 17 years old. He is installing this kit onto his personal GMC pickup that he just received from his grandfather, and he has plans to drive it every day to school. He wanted to have an engine that was not subject to the whims of carburetors. One of the things that EFI requires, however, is that the fuel system be a closed-loop setup. It also needs to have a higher fuel pressure than what is normal for a carburetor. That means the stock fuel tank must be replaced with one that has a tank-mounted fuel pump that has provisions for a return line. A call to Rock Valley was all it took to get a new aluminum tank. The tank fits back between the framerails and even holds more fuel than the stock unit that was behind the seat.
For those who think that fuel injection (thanks to the computer and the wiring it needs) is beyond their mechanical realm, think again. Or if you are worried that getting all of the parts together will be a huge hassle, think again. Thanks to Street & Performance, if you want to go the electronic fuel injection route, help is but a phone call away.
With the area clean, the old carb and valve covers are removed.
To get the new intake manifold to seal well, the heads need to be cleaned of any old gasket material.
A bead of silicone gasket is applied to the end rails of the engine. In this shot you can see that the stock fuel pump has been removed and a block-off plate has been installed.
Since it is hard to get to later, the S&P oil pressure tree has been installed. This piece will send a line to a gauge and is instrumental in working the S&P TPI system. It is oil pressure that controls the new fuel pump. When the oil pressure goes above 8 psi, the new S&P fuel pump kicks on and supplies a steady stream of fuel.
These intake gaskets are included with the S&P kit, and they are set into position.
The manifold is carefully dropped into place. S&P recommends that Teflon pipe sealant be used on the mounting hardware, as well as with the sensors.
The hardware is torqued to 18 lb-ft and in a pattern supplied by S&P.
After lubricating the rubber O-rings on the injectors, the fuel rails are installed. Anti-seize should be used on the mounting hardware.
Hooking up the new S&P harness is a snap (no pun intended), since all the connections are labeled. S&P even goes so far as to color-coordinate them. In this case, since the truck is a pre-’74 model, the EGR lead is not used, so it is just taped out of the way.
A dab of anti-seize should be placed on the hardware when you install the tube bolts. These will be torqued down to only 5 lb-ft. Also, it is recommended that the distributor be installed prior to the runners, since it just makes the job easier.
With the air-temp sensor installed into the bottom of the plenum (and the lead plugged into it), the plenum is set in place. Note that the plenum gaskets have been installed.
In the case of the Chevy truck, the fuel lines enter the engine bay on the passenger side. In this case, a Vette fuel rail has been used. If you need to have the lines enter the rail on the driver’s side, S&P can modify the setup.
The throttle body is installed. The hardware (four 8x75mm bolts) is tightened to only 5 lb-ft.
With the throttle body in place, the TPS, or throttle-positioning sensor, and the idle-speed motor connections are made
A Lokar billet aluminum throttle cable bracket and throttle cable are mounted.
A 1/4-inch plug, found on the side of the block, is removed, and in its place will go the knock sensor. This is only for systems that are using a speed-density-type system. Be sure to mount the sensor away from the spark plug wires, because the electrical pulses running through the lead wires can cause the knock sensor to give false readings to the computer.
An S&P 360-10-degree water neck was installed, as was a 195-degree thermostat.
The exit hose bib from the idle-speed motor housing was run to the heater input, and the breather tube was run to the valve cover vent (although not the one with a PCV valve).
With the Rock Valley fuel tank in position, the fuel lines were hooked up. The S&P system requires that a 3/8-inch feed line and a 5/16-inch return line be used. In this case, a set of Tube Tech nylon lines was used.
A stainless steel bracket comes with the S&P fuel filter. The filter will be mounted inline and up against the framerails.
Since the S&P fuel filter is supplied with two 16mm to AN6 O-ring-equipped fittings, so connecting to the Tube Tech lines is a snap.
Tube Tech also supplies these cool clamps to secure the lines in place.
S&P also supplies the 14- and 16mm to AN6 fittings needed to connect the lines to the fuel rails.
S&P also has radiator hoses and even headers, as well as all the brackets and hardware to install various items such as the alternator and power steering pump.
S&P even has these trick hoses that run from the power steering pump to the remote reservoir.
Now is the time to make sure all the fittings are tight.
To give the engine a finished look, a set of S&P spark plug separators was used, along with a Lokar dipstick. Also note that the oxygen sensor has been installed onto the collector on the driver’s side.
To keep the computer out of the weather, it was decided to mount it inside the cab. S&P has a lot of computer options for you, and even some that are fully waterproof.
But one thing that can ruin your whole TPI experience is a bad ground. S&P is adamant about the system being grounded well. The system is grounded to the back of the engine, which means that the engine must be grounded to the frame.
When the TPS is set, the EST bypass is unplugged so that the base timing can be set. The timing should be set to 6 to 8 degrees BTDC. The engine is turned off and the EST bypass is reconnected. With the EST connected, the timing will actually be between 16 to 22 degrees. Confused? No problem, as the S&P instructions will explain it all.
With the S&P throttle-position sensor pigtail hooked up, a digital voltmeter is connected to it. The TPS needs to be calibrated, so, with the meter connected, the TPS is rotated until the reading on the meter is 4.5-5.0 volts with the throttle in the wide-open position.
For those who have access to a scanner, this is the hot setup to dial in the timing and the TPS, and it is much easier than doing it with a timing light and a voltmeter. Since this truck had been equipped with a non-stock lift cam, the vacuum was weak. To compensate for this problem, the computer had to be recalibrated. But that was not really a problem, since Street & Performance does that and more—you just have to give them a call.
And that is it. The final shots show an engine that not only looks great, but is also one that will give peak performance with the best fuel mileage that you can get out of a V-8 engine. Where do we sign up?
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