Engine SWAP GUIDE 1985-1992 GM TPI EFI system engine into a 1970 - 1981 Camaro - NOW

This guide is designed specifically to swap a 1985-1992 GM TPI EFI system/engine into a 1970-81 Camaro. Though, for the most part, it can be used to swap in a TBI or LT1/LT4 engine/EFI system as well. All three engines install like a conventional engine on the existing motor mounts and they have the same transmission bell housing flange. The newest LS1/LS6 is a completely different animal altogether requiring extensive chassis modifications to install and will not be covered in this article. The first thing you need to take stock of is your vehicle and the system you will be installing. You need to also consider the emissions regulations in your state and how you will meet those requirements. I’ll touch on the emissions system briefly, telling how to hook it up. The emissions control systems are not essential to engine operation (save for maybe PCV and canister purge), but again, the emissions regulations will dictate their necessity from a legal standpoint. In California, there is a rolling 30 year exemption meaning that currently 1973 and older cars are exempt from smog. As such, I am not using EGR, AIR injection, or any of the other late model smog devices. However, I did retain my 1971 charcoal canister purge and PCV system. This article will cover two possible scenarios. The first is that you have bought an entire engine/transmission assembly or just the engine. You may or may not have the factory wiring harness and computer, you may or may not all of the sensors, injectors, and relays, or have bought new sensors to replace old or damaged ones. In this scenario, you have already taken out your old engine and or transmission and installed the new one in its place. You now need to reconfigure the rest of the vehicle to run the new power plant. If you are installing an LT1, this is your only scenario since the intake manifold cannot be bolted on to an older small block without extensive modifications. However, if you’re bent on doing something like that, visit the www.thirdgen.org site and do a search. Several people have adapted LT1 manifolds to work the TPI. I will touch briefly on the installation of a TH700R4 and how to adapt it in to a 2 nd gen since this is what I did. However, I will not discuss converting to a later model stick shift since I have no experience in that area. The second scenario is that you are putting the TPI/TBI system onto an older engine. In this scenario, you have already removed the old carbureted intake manifold and bolted on the new manifold. If you have TPI, only bolt on the base plate at this point. It’ll be easier to wire and plumb the system with the upper manifold and runners off (and the distributor out). Again, you now need to reconfigure the rest of the vehicle to run the system. I’m kind of glossing over the TPI base plate or TBI manifold installation part because putting on an intake manifold or installing an engine is pretty generic and can be found in any repair manual. The only caveat I have for this scenario is putting TPI or TBI on a seriously modified engine- that is, one that has a camshaft over 214° intake duration, cylinder heads with 180cc or more intake ports, full length headers and free flowing exhaust systems, etc. Stock TPI/TBI engines were extremely restricted as far as heads, cams, and exhaust systems go. Putting a bone stock EFI system onto a modified engine like this will result in poor, disappointing

performance if you do not get the EPROM recalibrated for the new combination. This will either require you to have a professional tuning shop do it, or you can learn to do it yourself. One thing to note before you get started is that I highly recommend using the 1990-1992 system. So much so, that I’m going to focus solely on installing this type of system. For reasons that will become apparent later in the guide, 1990-92 MAP systems are much more practical for EFI swaps than earlier 1985- 1989 MAF ones (see sensor section for definitions of MAP and MAF). If you have a 1989 or earlier MAF system, you can upgrade it to the 1990-92 configuration very easily. I’ll cover that later on. Another thing is that I would HIGHLY, HIGHLY suggest is buying a good automotive scanner! I use an AutoXray. It’s a very nice tool. It will read trouble codes, allow you to view real time operational data from the ECM (Electronic Control Module, aka, computer) as well as record it for future reference. You can also download this data into your PC and export it into Microsoft Excel for graphing and further analysis. This tool is invaluable for diagnosing malfunctions as well as for tuning, if you decide to get into that later. Actron also has a nice scanner, but it cannot record data. The main objective in an EFI swap is properly configuring the vehicle to work with the system. This involves two areas- fuel and electrical systems. Both need to be brought up to date. We’ll start with the fuel system. Vehicle Fuel System Preparation TPI/LT1 engines require a constant pressure of upwards of 40 psi to run properly as well as a return line to the tank. TBI’s operate on a much lower pressure of about 15 psi, but even they require a return line. In both cases, it means you will need an electric fuel pump. This presents you with two choices- either an in-tank pump or an external pump. At first glance, the external pump may appear to be the easier method, but it has several draw backs. The most obvious and complained about one is noise. Since you will be mounting the pump to the chassis, the humming of the pump will be transmitted through the frame and will be audible inside the vehicle. While only a mild annoyance, it takes away from the “factory-ness” of the swap. The second drawback is the heat generation. Cooling is mainly by convection (whereas an in-tank pump is submerged in a cooling medium, the fuel). Since there’ll be a lot of rubber (thermally insulating) padding to keep the pump mechanically isolated from the frame (to reduce vibration noise transmission) the heat conduction away from the pump is significantly reduced. Therefore, overheating the pump is a possibility. The third problem is fuel starvation. Unless internal baffling is added to the tank, low fuel levels combined with hard braking/acceleration and/or hard cornering can uncover the fuel pickup allowing

the pump to suck air. Electric fuel pumps do not like to suck air since it reduces the life of the pump significantly. In my opinion, the best way to install an electric pump is to go in-tank. It’s a lot easier than you may think and you eliminate all of the above problems. The key to the installation is to find a V8 or V6 late-third generation fuel tank sender like the one shown below. NOTE: It was recently discovered that a third gen sender does not fit into late second generation Camaro’s. It’s unknown the exact cut-off year. However, if cannot verify if the opening for your sender is not the same as a 1970-73, then this sender will not work with your fuel tank.

As you can see it has everything on it that you need and it’s a factory setup! Now, the beauty of this is that it will fit into a second generation fuel tank with minimal modifications. Namely: 1.) The depth of the fuel tanks between 2 nd and 3 rd gen tanks vary with the model year. As such, minor bending of the lines leading into the tank will probably be necessary. This can be accomplished by hand (but be gentle and don’t kink the lines!). Basically, measure the depth of your tank from the top flange of the sending unit to the bottom of the tank and make sure that the pump assembly is no more than 1/4” from the bottom. 2.) The fuel level electrical sender will operate the factory 2 nd gen fuel gauge perfectly (don’t you just love GM?). Both operate on a 0-90 ohm potentiometer operated by a float arm. However again, due to depth variations between tanks, you may need to do some minor bending on the float arm such that it is calibrated to the dimensions of your fuel tank. Just take the appropriate measurements and you’re set. 3.) As you can see, this sending unit has a lot of fuel lines. However on 2 nd gens, you only need two of them. Find the pressure line and the return line. The remaining two lines are evaporative lines and can be deleted since the 2 nd gen already has evaporator lines integral on the tank. On mine, I simply cut them a few inches from the root, pressed it flat about ½ inch from the cut end, and soldered the tip shut with standard Sn63 solder to ensure a leak proof seal (see diagram below) To plumb the lines to the tank you could use the stock 3/8 supply line that runs the length of the car as the supply line for the EFI. However, you would have to run high pressure rubber fuel injection hose from the supply line on the

sender to the line on the vehicle. You could also attempt to bend up some steel line to run the length of the car for the return line as well or attempt to use the vapor line as a return line. Some people have apparently done this successfully, but I’d rather not do it in such a manner. Again, you’d have to have rubber hose connections to mate up with the fuel sending unit. If you go this route, you NEED to use high pressure fuel injection hose!!! There would also be the need to plumb the steel lines into the fuel rail- calling for more adapters. I didn’t want to deal with all of the rubber hose and adapters and such so I ditched the 1971 steel lines and went the Earl’s braided line route. Basically, I bought fittings that allow you to hook up –AN braided steel hose to a steel fuel line. Today though, Earl’s has tubing adapters that are specifically designed to allow you to hook up braided steel line to the steel tubing. Simply call them up and as for fittings that allow you to hook up -6 AN line to 3/8” steel tubing. They also have fittings that utilize the factory fuel rail connections and allow you to plumb the braided hose right to the fuel rail. This gives the benefit of running a one piece line from the tank to the fuel rail (not counting the in-line high pressure fuel filter of course). Not to mention that flexible braided steel hose is a lot easier to route than rigid steel. One thing to keep in mind here, try to maintain as few connections as possible since each additional connection is a potential source for leaks! Below is a EFI fuel system block diagram: NOTE : I recently discovered that gasoline can permeate through braided rubber fuel line and result in a constant fuel odor, particularly when the vehicle is parked inside a garage. This is most likely due to various fuel additives in certain parts of the United States. One possible remedy, aside from hard steel lines, is to run braided teflon lines. Teflon lines are available from a variety of sources. While I did this option on my Camaro (which ridded me of the fuel smell), Aeroquip has posted a disclaimer about running any type of braided line on EFI engines. http://www.aeroquip.com/media/performance/A-SPPE-MC001-E-p54.pdf The fuel recirculation can oxidize the fuel which can allow to attack and deteriorate the hose. Therefore, I am not recommending running braided hose , but merely presenting the option as many people are already doing this rather than forming hard steel lines.

Lastly, the fuel starvation problem needs to be addressed. 2 nd gen fuel tanks were obviously not designed for EFI. Electric pumps meet an early demise if starved for fuel too many times which is why late model fuel tanks have complex baffle systems inside. This prevents starvation during high-g maneuvers. On my tank, I did the best I could to mimic the baffle philosophy by welding in a tray on the bottom of the tank. Basically, a gas tank shop cut out a section of the tank floor, welded a tray to it and then welded the floor back in. The tray looks like just that, a tray. It’s rectangular and a couple of inches tall. It has four holes (one at each corner near the bottom of the tray walls) to allow fuel to slowly enter in to the tray, but keep it from getting away from the pump. I forget the exact dimensions (since I did this about 7 or 8 years ago) but I would suggest a tray about one foot long by about one foot wide by about two to three inches tall. Here’s a generic view of what I’m talking about. The pump doesn’t necessarily have to sit in the tank like this though. In fact, with the third gen sending unit, the pump will be pointing toward the back of the tank.

In any case, the then hangs down and sits in the of the tray. This is not a sump. From the outside, the tank looks stock. This baffle tray is completely inside the tank. What I would suggest is to fit your fuel tank sender in and then take the tank and sender to a shop and describe what you’re doing. If they are at all able to do some custom work they should be able to do this. That’s basically how I did it. For the pump itself, I’m running a Holley high-performance in-tank pump. It feeds my modified ZZ4 (~400hp) just fine. Another option for an EFI fuel tank is to contact Rock Valley (www.rockvalleyantiqueautoparts.com/history.htm ). They can build a custom stainless steel tank for your 2 nd gen Camaro. The tank already has baffles in it and is setup for EFI. It’s pretty pricey at about $1000, but it comes ready for use. The above applies to all TPI/TBI/LT1 engines. Like I said, the only thing that will vary is the type of pump used- TPI/LT1 vs. TBI. Obviously, the higher the horsepower and displacement of the engine, the higher the pump output you’ll need. While I’m on the subject of the fuel systems, let’s talk injectors and fuel pressure regulators. Since I don’t recommend putting TBI on a high performance engine, I’m going to stick with the TPIs and LT1s. They use the same injectors. 305 TPIs came stock with 19 lb/hr injectors, on 350 TPIs that was increased to 22 lb/hr. When the LT1s came out, they received 24 lb/hr units. Rule of thumb, if you’re aiming for over 350 hp (which is pretty easy these days), upgrade to 24 lb/hr injectors. Additionally, don’t try to run 305 injectors on a 350 (especially if it’s a modified 350). They have insufficient capacity to feed that much displacement. The cheapest place I’ve found that sells injectors is Summit Racing. Matter of fact, I’m running Ford Motorsport 24 lb/hr injectors! I know… “HERESY HERESY TRAITOR!!” Hey what can I say, they use the same injectors that GM does, but they charge about half as much. At Summit, they cost about $220. For the regulator, you can run the factory regulator, but you’ll stuck with the factory fuel pressure. While not really a bad thing, but if you want

to up the pressure a little you’ll have to install an adjustable fuel pressure regulator. There are a ton of them out there- Crane, TPI Specialties, Granatelli, Holley, etc. They’re all pretty much the same, so whatever strikes your fancy. Injector operation varies between TPIs and LT1s. All TPIs were batch fire systems. That is, the computer alternately fires all four driver side injectors then all four passenger side injectors. 1993 LT1s had the same style injector operation. However in 1994, GM changed to sequential injection where each injector is timed to fire per the engine firing order. Sequential injection has a little bit of an advantage at low RPMs (usually showing up in idle quality). But in the mid-range and high RPMs, the speed of the engine is high enough that the timing of the injectors becomes less important. Lastly, remember that you need a high pressure EFI fuel filter!! And, it’s directional at that. Make sure you install it with the arrow (on the filter housing) pointing in the right direction!!! Well, this pretty much takes care of the fuel system. Vehicle Electrical System Preparation The electrical system of an EFI system is not as complicated as you might think. Nonetheless, the vehicle must first be prepared to handle the demands of a late model engine management system. Like I said previously, they call the system “stand-alone” because of the system’s minimal interfacing with the rest of the vehicle’s electrical system. On the EFI harness, the only places where the system connects electrically to the vehicle are power and ground. There is one hook up to the battery, one hookup to +12V switched power source, and a few ground locations (typically engine and chassis). As such, the system basically stands alone. I will take you through the electrical preparation, but also guiding you through the engine schematic explaining the sensor operation. Again, this is something most TPI swapping guides do not do. If you are unfamiliar with wiring schematics, this will help you familiarize yourself with them. It’s important that you do so that when problems arise with the installation (and they usually do the first time through), you will be able to more successfully diagnose the situation. First of all, you need to make sure that your vehicle’s electrical system is up to the task of powering an EFI system! Remember, you’re going to be adding eight fuel injectors, a computer, a fuel pump, electric fans (likely), sensors, relays, etc. This is going to place a much heavier demand than your original electrical system was designed to handle. First, examine your power wire going from the battery to the alternator- make sure it is in good condition. In fact, I would strongly suggest upgrading it to a heavier gauge wire since you’re going to have to have a high output alternator. Also, ensure you have excellent (not just good) grounds going from the battery to the engine, engine to chassis, and even battery to chassis. It sounds redundant, but trust me, EFI systems do not like electrical ground loops. All of your chassis grounds from the EFI harness must

Engine SWAP GUIDE 1985-1992 GM TPI EFI system engine into a 1970 - 1981 Camaro - NOW

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