Be sure you install your tpi system on a engine in sound mechanical condition. A engine that is worn out or in bad mechanical condition will not allow the tpi system to perform to its optimum. Not only will you have to eventually take it apart to replace the worn out engine, if at the very least will make it difficult or impossible to troubleshoot any problems with the tpi set up. You may get by for a little while, but eventually it will catch up to you, costing at least twice as much in time and money!
Once you have decided to make that leap into fuel injection, you'll have to gather all the parts you need to get started.
The picture below shows the parts for a complete manifold. If you buy a partial set up, individual pieces can get expensive...quick.
Pictured above is the typical set up for a 1986-89 MAF based system. Speed density is similar. (A) Intake manifold. (B) EGR valve (C) EGR temp switch (maf only) (D) PCV fitting, to the left is orifice for cold start injector (maf only) (E) Thermostat housing neck and bolts (F) Bolts needed for top plenum and runners- 13- M8x1.25x30mm, 2- M8x1.25x40mm, 4- M8x1.25x50mm, 1- M8x1.25x30mm throttle bracket stud, 20 total, these use a T40 Torx head bit, NOTE these are metric. (G) Fuel rail typical for a "F" body, maf system, fuel lines for Corvette is on opposite side. Look at picture, as this is a complete system (H) cold start injector and fuel tube (maf only) (J) Fuel injectors-8 total (K) Intake runners, speed density will not have the cold start opening (L). (M) Intake air sensor (P) Intake plenum, with throttle body, be sure to get complete throttle body with no missing upper and lower cover plates, bottom plate has provisions for IAC and coolant tubes. (Q) Throttle bracket and bolts (R) Vacuum fittings for fuel regulator, heater control and brake booster, speed density will have a fitting for MAP sensor and mounting boss.
The Corvette intake has provisions for the egr on the back side of the manifold, corresponding to the special exhaust manifold that goes with it. This is because the Corvette engines came with Aluminum cylinder heads that had no heat riser passages, therefore the egr gases had to be routed from the exhaust manifold. The intake still uses the central mounted egr valve that functions like all other tpi intakes.
Whether you get them at a swap meet or from a donor car, be sure to get the complete set up. Missing pieces can get expensive, quickly! A complete set up should include the lower intake, left and right side runners, top plenum, distributor cover plate which bolts on the back of the plenum, throttle body, the complete fuel rail and fuel regulator, fuel injectors, egr valve (which set in the center of the intake), thermostat housing, throttle cable bracket. The air cleaner assembly and tubing, every nut, bolt and bracket that attaches to the intake system, and to the accessories brackets. You may or may not need the air intake assembly and brackets for your particular application, but it will not hurt to have them on hand, because you'll never know exactly what you need until you get ready to fabricate your set up.
If you plan to use a overdrive transmission such as the 700R4 or 200-4R, you'll probably have to have the drive shaft modified to fit. Also the transmission cross member will have to be relocated. You'll have to modify your shift cable bracket to fit the transmission, but this is not difficult to do.
You must be able to use the VSS (vehicle speed sensor) with your tpi setup, even if you don't use a overdrive transmission. The VSS is needed because many tpi functions are directly related to it, such as idle speed and A/F ratio, etc. There are aftermarket suppliers such as B&M that has a speed sensor kit so you can use the VSS.
Don't count on top performance from your TPI without it. Also without the VSS, the engine could stall under deceleration, making the vehicle dangerous to drive.
NOTICE: When you install your manifold gaskets, thermostat gaskets, and any other gaskets that require a sealer such as rtv, be sure to use only a "sensor safe" or OEM ( Original Equipment Manufacturer's) sensor approved rtv sealer. Failure to do so will destroy your O2 sensor.
Another thing to be aware of is the vacuum lines. You can get by with some modifications, and some of the small 1/8" lines can be found on many GM late model vehicles, along with the rubber adapters to mate them together. Example below is for the location of the typical tpi vacuum lines that may have to be modified if you are using anything but "stock" valve covers.
First picture shows mods needed with heavy die-cast aluminum valve covers. (A) shows the valve cover grommet that can be purchased at any automotive store, along with the elbow connector (B) is the aftermarket fuel/pcv hose. The second picture shows the pcv valve grommet and the "y" fitting to split the line which also goes to the purge control valve on the vapor canister.
Click [here] for vacuum line schematics.
Be sure that the plenum and intake and runners match. The 1985-88 intakes have provisions for the cold start injector in the intake and the left side runner. (picture 1) The 1989 and later intakes eliminated this passage in the runner and intake. The 1985-88 tpi intake plenum also has a idle air passage that is not present on the 1989 and later intakes, since the cold start injection was eliminated. (picture 2). The throttle body has a matching opening for the idle air passage, the later throttle body can be used on a earlier intake but not vice versa, if you plan on using a speed density system. It must be noted here that even though the cold start injector was eliminated for the 1989 model year, the system was mass air flow. The Corvette intake has a special provision on the right rear of the intake that plumbs into the exhaust manifold, unless you get the complete engine with the exhaust manifolds that clear the frame in your car, avoid this intake.
There are also minor differences on the intakes as far as the mounting to the cylinder heads. The 1985 and 1986 intakes will fit on 1986 and earlier heads. Starting in 1987 the angle of the two center bolts on each side was changed and these intakes will fit 1987 and later heads, unless you want to drill the angle steeper to fit.
Another thing to watch, is the distributor. 1985 and 1986 engines used the flat tappet hydraulic cam and lifters, if you pull the distributor from this earlier engine be sure you plan on using it on a 1986 and earlier block. This is the familiar large cap HEI distributor. In 1987 the engine block went to roller cam and lifters and the distributor is smaller with remote coil. The use of the roller cam meant that a special metal was used in the distributor gear to make it compatible with the steel billet cam. If you have a 1987 and later block, be sure to use this distributor. If you plan to use the earlier distributor in a later block, you will have to change the distributor gear. Many specialty parts suppliers have this item. The same goes if you plan to use a later distributor in a earlier block. If you think you can get away without paying heed to this, the cam and distributor will chew itself to pieces, circulating metal debris throughout your engine. This page is for distributor mods. shows electrical mods to swap distributors.
If you are building a 283, 305 or 307 cu. inch engine use the 305 TPI system. If you are building 327, 350, 383 or 400 cu inch engine, you'll need the 350 TPI system. The main difference in these systems is the rated flow of the fuel injectors. The 305 injectors are rated at 19lbs/hr, while the 350 injectors are rated for 22lbs/hr. There are some modifications you can do to allow the 350 injectors to flow sufficiently for a 383, 400 cu inch engine but this is described in the [performance page] page. Another thing to make note of is the difference in fuel management. Mass Air Flow systems are more forgiving up to around 10-15% difference from the stock air flow to allow for a slightly modified system, including ported heads and intake, a hotter cam, free flowing exhaust, but even this must be taken with caution, as once you pass the threshold of tolerance, you'll need higher flow injectors and a modified prom chip for the ecm. A speed density system although allowing for a simpler air intake plumbing, is not forgiving in the fuel parameters in which the prom was designed for. Any changes whatsoever to the engine components will guarantee a modified prom chip.
Also, if you are using a MAF system like I did on my Camaro, you'll need to modify the thermostat housing, add an electric fan, and modify the air cleaner housing. I have pictures and descriptions for these also. Be sure to get all the brackets necessary to mount your A/C, power steering pump, alternator. One word of the alternator bracket- the 1985-1987 TPI's with the "V" belts have their own unique bracket you must get.
If you are pulling a tpi from a 1987 and later tpi car with the serpentine belt and what to use this (as I did), be sure to get all the brackets and pulleys.
My 1978 Camaro TPI engine install July 2, 2000
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