In other words, an 85-89 TPI knock sensor is different from a 90-92 TPI knock sensor. They physically look the same, but will not interchange. The 85-89 TPI setups used two different knock sensors (one for 305s, the other for 350 engines) from the 90-92 setups, which also had two different knock sensors (one for 305s, the other for 350 engines). The second difference between the two pertains to the knock sensors. These used a mass air flow sensor to calculate air being drawn into the engine. Instead, a manifold absolute pressure (MAP) sensor is used to measure engine load (basically, engine vacuum). Likewise, the 85-89 setups do not use a MAP sensor. The most obvious difference is the lack of mass air flow (MAF) sensor in the 90-92 setups. Sensors: The sensors needed for a MAF intake are very similar to those needed for a MAP intake. The 85 TPI harnesses will work only with the 1226870 ECM, and the 86-89 TPI harnesses will work only with the 1227165 ECM. Obviously, the earlier MAF computers will use a different harness as well. Each computer will use a different harness, as the ECM connectors are different, and the harness dimensions change as well. For example, if you have decided to run a 90-92 system (MAP), you can use a 1227730 ECM (mounts in the passenger compartment) or a 1227727 ECM (mounts in the engine compartment). Wiring Harness: The harness you decide to use will depend on what type of TPI you decide to use, and what ECM you choose. We offer this service for a very low rate, contact us for details.ĮCM and PROM: Once you decide what type of TPI system you would like to run (MAF or MAP), you can read through our ECM and PROM article for more information on the differences between each. A much easier way to go about running a different injector size is to have the injector size changed inside the PROM. This will put extra stress on your fuel pump. In order for 19 lb injectors to behave like 22 lb injectors, your fuel pressure must be raised from 43.5 psi (stock setting) to about 56 psi. This can be done, but barely anyone does it properly. The Corvettes did not have larger injectors, as people often believe.Īlot of people suggest running 305 injectors on a 350 by raising the fuel pressure (this requires an adjustable regulator).
All 305 TPI engines used 19 lb injectors, and all 350 TPI engines used 22 lb injectors. Injectors: If you will be using a stock PROM, then you must stay with the stock sized injectors for your engine size. Your intake may or may not include sensors, but if they are included, they should be tested to make sure they are functional
BIG CAM 350 RAIL PRESSURE DRIVER
Most of the time, some of the bolts are missing, and some of the brackets may be missing as well. Make sure that you have a throttle bracket on the driver side of the plenum, as this is where the accelerator cable mounts. Also, the thermostat housing is an item that is often missing, so make sure you have one before beginning your install.
When you purchase an intake, it will usually include the manifold base, a pair of runners, plenum, fuel rails, and throttle body. However, you can run TPI on Vortec heads if you use an aftermarket intake manifold from Scoggin Dickey. The four center bolt holes are angled differently on the 87-92 intakes. A stock TPI intake with not work with Vortec, or LT1 heads. The bolt pattern changed in 87, so if you have 86 or earlier heads, you need an 85 or 86 manifold base. Keep in mind that you need an intake that will bolt to your cylinder heads. Actually, you can run any ECM and harness on any intake with little work.
You do not necessarily have to buy a 90-92 intake if you want to run a MAP system, and you don't necessarily need to buy an 85-89 intake if you want to run a MAF system. In addition, the later intakes usually cost more. Intake Assembly: When looking for a used intake assembly, you will find that it is easier to find an older 85-89 MAF intake than it is to find one of the 90-92 MAP intakes.