Posted - 04/13/2007 : 2:44:13 PM
| Corvette Injector Cover Installation:
By Scott Mueller
Way back in early '94 when I first picked up my Impala SS I was fairly disappointed when I opened the hood. You see I had read that the Impala engine compartment was supposed to contain one of the most powerful smallblock Chevy engines ever, the LT1. Unfortunately it did not look like an LT1, at least not like the one in the Corvette.
After studying both the Corvette and the Impala engine bays, I determined that the dramatically different appearance between these two nearly identical engines was limited mainly to the dress items attached to the top of the respective engines. After studying both the 'vette and Impala parts catalogs I determined that it would be very easy to duplicate the look of the Corvette LT1 in the Impala by first removing the "home plate" induction resonator and it's bracketry, and then installing the fuel injector rail covers and valve covers from the Corvette. This was surprisingly easy, and so dramatically changed the look of the engine, other Impala owners thought I had changed the engine itself!
Although these items can very easily be installed, there are a few modifications and adjustments that must be made, and several different parts are necessary to complete the job. The major appearance change comes from adding the Corvette fuel injector rail covers, and you can optionally also install the plastic Corvette valve covers as well. Since the valve covers are a direct bolt-on, there are no instructions necessary for them, other than what is already contained in the service manual. This text will focus on installing the fuel injector rail covers, which are a little more complicated.
First let's start with the parts list:
GM Parts needed:
10208794 Corvette LT1 Fuel Rail Cover LH ('94+)
10208795 Corvette LT1 Fuel Rail Cover RH ('94+)*
10224936 Corvette LT1 Fuel Rail Cover RH ('92-'93)**
10108672 Fuel Rail attachment studs (you need 4)
10260166 Accelerator linkage Cover
10242904 Accelerator linkage cover Bracket
11505169 Accelerator linkage cover Screws (10)
10214035 Corvette brake vacuum booster hose
8919356 3/4" ID convoluted plastic tubing (15 ft.)
20038997 Clip for Accelerator and Cruise cables (you need 2)
* Use this if you ARE also changing to the '94+ 'vette plastic valvecovers
** Use this if you are NOT changing to the '94+ 'vette plastic valvecovers
Generic or miscellaneous parts needed:
Brass fitting - 1/4" male pipe to 3/8" ID hose barb
Reducer Coupling - 1/2" to 3/8" hose barb
Waxman Nylon #07-832 (Available at Builder's Square)
NOTE: Optionally you can use the following brass fittings to construct a 1/2" to 3/8" hose barb reducer coupling:
- 3/8" pipe double female union
- 3/8" male pipe to 1/2" hose barb
- 3/8" male pipe to 3/8" hose barb
Washers - 3/16 (you need about 10)
Special tools needed:
Fuel Line Disconnect - 5/16" and 3/8" KD Tools #3321
Drill bit - 7/8"
Before beginning the injector cover installation, you will need to disconnect and re-route the power brake booster vacuum hose. To do this you will use the smaller diameter Corvette brake booster hose from the intake manifold back to behind the engine, where it will turn and then be spliced to the original brake vacuum hose. Both hoses will have to be trimmed in length, and you will have to make up a double ended barbed fitting to splice them together.
Because the Corvette brake vacuum hose is smaller in diameter than the stock hose (11/32" ID compared to 1/2" ID), you will need to change the brake vacuum fitting in the intake manifold from the existing 1/2" hose barb to a 3/8" hose barb type. This allows you to attach the smaller diameter Corvette formed brake vacuum hose. The portion that screws into the intake manifold is 1/4" pipe thread. I like to use teflon sealer on the threads before screwing the fitting in place. Remove the original fitting, take the 1/4" pipe to 3/8" barb fitting, apply some thread sealer, and screw it into the manifold where the original fitting was positioned.
Then attach the Corvette brake booster vacuum hose to this fitting and run it back towards the firewall along the intake manifold valley, and then around behind the LH valvecover. There you will splice that hose to your existing brake vacuum hose with a 3/8" barb to 1/2" barb adapter made up from the brass double female union and 3/8" male pipe to 1/2" and 3/8" male pipe to 3/8" barb fittings. This brass splice can later be covered with the 3/4" convolute plastic tubing for a totally factory look.
Once the brake vacuum hose has been re-routed, you will need to disconnect the fuel lines at the regulator in order to re-route the main engine harness behind the fuel lines. First *IMPORTANT* you must relieve fuel system pressure and use several rags around the fuel fittings when disconnecting them. I recommend you do this on a cold engine and have a fire extinguisher (preferably HALON type) nearby. To relieve fuel system pressure, follow the service manual guidelines, or disconnect the fuel pump electrical connector at the rear of the vehicle, start and run the engine until it dies, and then relieve the remaining pressure by depressing the fuel rail schrader valve, using a rag to catch the fuel that will come out.
Then proceed to disconnect the fuel line fittings with KD #3321, and wire or tape up the fuel line ends at the firewall to prevent any siphoning of fuel from the tank or dribbling out of the lines. Use the rags to catch any fuel that might dribble out. With the fuel lines now disconnected and secure, reposition the main engine harness to route behind the fuel rail fittings. Then bend both fittings to align with each other, so they project up at the same angle. I used a small screwdriver inserted in the steel lines to act as a handle for minor bending.
Now get the LH cover, and position it in place the best you can. The purpose is to get an idea of where to drill the holes in the cover for the fuel fittings to pass through. The holes will be much larger than the fittings, so you can easily remove the cover in the future and slide it up on the fuel lines without having to disconnect them. If you like, you can notch the cover later by using a hacksaw to continue the holes towards the rear, but it looks much better with just the holes and the fuel lines passing through them.
Now take the cover and drill two 7/8" holes where you estimate the fuel lines will pass through. It is OK if you are off by a little, as the steel lines can be bent slightly to center them in the holes once you put the cover back on. Now set the cover over the steel fuel lines, and check for fit, bending the lines as necessary so they are centered.
Now install the metal studs in the intake manifold. I found that it was necessary to use some 3/16" washers under the two studs on the LH side to raise them enough to get the cover to properly engage. This is only necessary for the LH cover due to the thickness of the wire and hose bundle underneath it. You will have to do some rearranging and compressing of the wire and hose bundle, to get everything to fit nicely with the cover on. In some cases you will have to file down the metal fuel regulator bracket in order to get the injector cover to seat down properly.
After the LH injector cover is in place, re-attach the fuel fittings. They are quick connect fittings and should just literally snap into place. Reconnect the fuel pump electrical connector at the back of the car and be sure the schrader valve cap is installed, then turn the key on (don't start it yet) which will pressurize the fuel system, and check for leaks.
The RH injector cover is much more easily installed than the LH side. If you are using the '92-'93 style cover (which is required if you are not changing to the Corvette plastic valvecovers), then you may need to trim it in the area where the MAP (Manifold Air Pressure) sensor is mounted at the RH side of the throttle body. Also you will likely have to bend the transmission fill tube to clear the cover at the rear. Bend the transmission dipstick tube back towards the firewall, and to the left towards the wiper motor. After tucking the wires and solenoid down into the intake manifold valley, the RH injector cover should neatly snap into place.
After the injector covers are installed, the plastic cable clips will go into the two holes in the LH cover, and hold the accelerator and cruise cables close to the cover for a neat appearance, and to prevent them from abrading against the hood insulation.
Now you can install the throttle linkage cover. You must remove the splash shield that is currently there, it will be discarded, along with the bolt that held it in. Remove the LH upper throttle body screw and attach the short "L" bracket for the linkage cover underneath it. Set the cover in place and use one of the small screws you bought to attach it to the linkage bracket.
There, that should about do it, now your engine looks like a REAL LT1!