By:
Jeff Flint - Washington State
Director/ZR-1 Net Registry
Robert Melbo - Oregon State Director/ZR-1 Net Registry
Looking under the open hood of a ZR-1 can be a scary proposition. Lines run every which way and the possible expense of a misplaced screw or broken part can send shivers down the spine. What looks to be a nightmare is actually quite simple in reality. Part 1 will look at the removal of the top end, while Part 2 will focus on the cam covers for refinishing to bring new life to the engine.
At this point, coolant should be drained, and the battery disconnected. {IMAGE#1}{IMAGE#2}
Plenum Removal
Tools Needed: T-40 (2" long bit), T-15, 7mm socket, 6mm socket, 1/4"
socket, flat blade screwdriver.
Start by removing the air duct. It is held on by two band style clamps, which are accessible from the passenger side underneath the duct. Proceed to the throttle cable screws (T-15) on the top of the plenum, and finish with the two 7mm nuts holding the side of the throttle cable cover & on the front of this cover, the front bolt (T-15). The throttle cable(s) can now be removed by holding the throttle blades open to relieve tension. Now start removing vacuum lines, PCV lines and hard coolant line on the passenger side. Disconnect the TPS, IAC, IAT, and MAP sensors. On 1993-1995's, the EGR hose is held in by two 6 mm bolts. The plenum bolts (T-40) can now be removed. {IMAGE#3}
Now is the big moment. Gently
lifting the air horn up, you'll see the gasket surface between the
plenum and injector housings become exposed. Depending upon the age of the car or the last time the plenum
was pulled will determine how much the gasket will deteriorate. Usually
the gasket will either stay with the injector housing or plenum. Just
aid the gasket in peeling off the opposite surface if you need/want to reuse the
gasket. While slowly lifting the
plenum, there are a few vacuum hoses that need to be addressed.
1990 Vacuum hose at the base of the air horn in between the alternator and
AC compressor {IMAGE#4}
1990 EVAP hose going to the driver side front of the car {IMAGE#4a}
1991-1992 EVAP hose at the base of the plenum going into the "V" of
the block {IMAGE#5}
1993-1995 EVAP hose at the base of the plenum going into the "V"
of the block and additional MAP sensor {IMAGE#6}
On all 90-95 cars there are four connectors for the ignition module. Two are at the front of the module and are retained by a clip based connector. The two in the rear; one is clip based and the other is held in place by a 1/4" bolt. Having a second pair of hands to assist eases the removal. After the connectors are removed, pull the plenum straight up and off the engine, and place to the side.
{IMAGE#7}
After Plenum removal you should be looking at this
{IMAGE#8}
Fuel Rail Removal
Tools Needed: 10mm socket, possibly T-40.
First step is the removal of the electrical connectors for the injectors. Press and hold the spring clip towards the neck of the injector, then pull the connector of the injector. The fuel rail is held on by four 10mm remove bolts. Then, take a long prybar (many tools will do the job) and lay a cloth on top of the injector housing surface and gently pry the fuel rail up. It should pull the injectors out of their mounting holes. The fuel rail can be turned towards the passenger side fender are or laid up on the windshield upside down. An option is to remove the three bolts (T-40) that attach the fuel lines to the fuel rail. Before you remove the fuel rail, bled off any pressure using the schrader valve, and also uncap the gas lid.
Injector Housing Removal
Tools needed 10mm socket, flat blade screwdriver.
Driver side: The driver side is straight forward. Start with the coolant pipe hose connector, depending upon your build, you may have a screw type clamp, or a spring tension clamp. Undo the clamp for the breather box/PCV system. Remove 9 bolts (10mm) that hold the injector housing down. Slowly lift the injector housing off the cylinder head. These gaskets will either tear or be permanently attached to the injector housing.
{IMAGE#10}
Passenger side: Small difference. The alternator has a small tab or brace attached to the injector housing. Each bolt is a 10mm. Unbolt the tab from injector housing and alternator. Remove the remaining 8 bolts from injector housing and slowly pull up, remembering to undo the breather box hose clamp and coolant pipe hose.
{IMAGE#11}
In the middle you will have a mess of vacuum lines, plug wires and wiring harness. Tape up the oil galley holes and also the cylinder intake ports to keep any garbage/parts/tools from falling in.
In the next issue we will continue on and remove the cam covers, breather box, coil packs and a few other parts for extensive cleaning.
