Jeal Header Install – 1994 ZR-1

by Nick Solandros

 

 Last Update: 10/23/2004

 

Preparation

 

This is a big job.  You should psyche yourself up for this, and if you drink, make sure you have plenty of your favorite spirits on hand.  I used the job as a stress relieving exercise, and it worked.  The total time I have invested in this job, from start to finish, is 18 hours working by myself.  Also, it really helped me to stay organized.  In the middle of the longest workday (12 hours) I stopped and re-sorted all of the many tools I had pulled out of the toolbox, as well as re-sorted and stored all of my tools at the end of each work session.  All in all, it was a fun project.

 

Here is a description of the job at hand:

 

Disconnected the battery.  Loosened the front lug nuts and then jacked the car up and placed it on 4 jack stands, as high as I dared go with my floor jack and two 2x4’s under the rocker panels.  I then removed the front tires, the inner fender panels and the ASR assembly on the left side (more on the ASR assembly below).  There are several things (i.e., fuse boxes) that bolt to the inner fender panels that must be removed, but reassembly is not that bad as everything makes sense where it eventually gets reattached.

 

Removal of Stock Exhaust Manifolds

 

This is the REALLY fun part.  Get ready to bleed.  This involves disconnecting and/or moving everything out of your way so you can access the exhaust manifold bolts.  But first, you will have to disconnect the cat-back exhaust system from the cat converter extensions.  On the later model ZR-1’s, the catalytic converters bolt to the exhaust manifolds.  If you can remove the stock cats from this point, do so.  I could not get all of the bolts out, so I ended up leaving them attached and removing the cats and manifolds as a unit.  The bolts were just too dry from 64,000 miles of use.

 

Disconnect the oxygen sensors at the weather pack connections that reside alongside the bottom side rear of the engine block on both sides.  You will have to remove several pieces of the factory exhaust shielding that surrounds the stock manifolds as well as lining the surrounding areas.  The shielding that is bolted to the underside of the floorboards can stay, and should remain at the end of the job to shield the header collectors (or, in my case, the Random Tech bullet cats) from the fiberglass floorboards.  I wore heavy leather gloves when sliding the shielding out from under the car to minimize the blood loss.  The shielding has sharp edges.

 

Unbolt and move up onto the top of the plenum the ASR assembly.  There is one vacuum line and two electrical connectors you will have to remove under the ASR module; one of the electrical connectors is for the ASR module, and the other is for the diverter valve that is part of the cold start A.I.R. injection system.  If you remove the A.I.R. injection system (and I recommend you do just that!) you will have to tape off and seal up this electrical connection, and plug the vacuum line “T.”

 

From the side of the engine through the fender wells, remove as many of the manifold bolts as you can reach.  The rest will have to be removed from down below.  Also, you will need to remove a small shield from the right side of the engine block to gain access to the oil dipstick entry point, so you can remove the dipstick tube.  Its not hard.  The dipstick comes out easier once you have all of the manifold bolts removed; then you can wriggle the dipstick tube around and fish it out from up top.  Save the bolt spacer that fits between the dipstick mounting flange and the exhaust manifolds.  You will re-use it when reattaching it to the header flange.

 

You will also have to remove the A.I.R. injection system plumbing.  This stuff is insidious, and resides everywhere.  Just follow the hoses from the A.I.R. pump in the front left corner of the engine bay, and you’ll see what I mean.  Take off as much of that stuff as you can.  There is also a hard line that runs down and under the engine to the right side.  Removal of all of the A.I.R. systems is not complicated, and will be self-evident.

 

Removal of the EGR Valve

 

Oh boy, get ready for even more fun!  The EGR valve is removed in concert with the right side exhaust manifold.  First, try to locate the valve.  It bolts to the engine block on the right front side of the engine, down low, just in front of the engine mount.  There is a hard line running from the right side of the plenum to the EGR valve, as well as from the EGR valve to the right side exhaust manifold.  Both of these tubes must be removed, but you may not be able to remove them from the EGR valve before you remove the valve itself.  Once you see how crowded the space is in there, you’ll see what I mean.  Removal of the hard line from the exhaust manifold is best accomplished with a large flat blade screwdriver.  The line is secured in the manifold with a metal crimp clip.  I pried it loose with the screwdriver enough so that the tube would slide out of the manifold.  Then, remove the other end from the plenum, and snake it out from behind the coolant pipe and everything else that sits in the way of its removal.  Be careful not to scratch the finish on the plenum runners or the coolant pipes.

 

First, you should remove the engine mount nut from the frame on the right side, and loosen the same nut on the left side.  I think you could get the EGR valve out without doing this, but removal of the nut does make it easier.  Then, take your floor jack with a chunk of 2x4 on the lift plate, place it under the engine oil pan, and jack up the right side of the engine.  I raised the engine about 4 inches, enough so that the engine mount dowel was pulled free of the mounting hole on the right side.  Then, from the right side of the engine, it will be fairly evident where the bolts are to remove the EGR valve.  Basically, the valve itself bolts to a cast iron mount, and the cast iron mount bolts to the engine block with three 10mm bolts.  Remove the three bolts securing the cast iron mount, and you can then remove the mount and the valve together.  There is also an electrical connection to the EGR valve; don’t forget to unclip this prior to removing the valve.  Its easier to unclip once you have removed the mounting bolts.  Tape off and seal this connector, as it will no longer be used.

 

To reinstall the engine mounting nut, I had to do some careful manipulation of the engine.  I had jacked the engine up high enough that the engine mounting bolt had pulled out of the frame, and the engine moved sideways on me so that when I went to drop the engine back onto the mount, the bolt no longer lined up with the hole in the frame.  I had to use a long crowbar and pry on the engine mount from the side of the car with one hand, while manipulating the lowering handle on the floor jack with the other hand.  It took me awhile to get everything lined up again, but I finally got it.  This is one part that definitely would have been easier with two people.  Not impossible, but a bit worrisome for a moment or two!

 

Removal of the EGR system will save you about 5 pounds of weight, not to mention you get one hell of an ugly piece off of your engine!  It’s a bizarre looking apparatus.  Throw it in the corner, have a drink and forget about it.

 

Removal of the A.I.R. Injection System

 

A must do, in my opinion, unless required by State law or a visual inspection.  If you have removed all of the A.I.R. tubing from the exhaust manifold location, you are almost home free.  The A.I.R. pump mounts in the front engine compartment, down by the left side headlight.  It is secured to a bracket using three bolts.  Remove them, and then  remove the two electrical connectors to the pump.  Once is a fusible connection, the other is the power lead.  Tape off and seal both connectors, as they will not be re-used.  Also, the pump connects to a plastic intake nozzle that sits alongside the radiator shroud.  It all comes out together with a little twisting.  Removal of this system saves you at least another 5 pounds, and you won’t have to listen to the pump running on cold start.

 

Installation of the Jeal Headers

 

The Jeal headers are visibly high quality units.  You will love these pieces; they are gorgeous.  Too bad you can’t really see them from up top once they are installed!

Make sure you use new exhaust manifold gaskets, and then install the headers from below the car, one side at a time.  Get as many bolts in the cylinder head mounting holes as you can, to minimize any potential leaks.  I managed to get bolts into every hole on both sides, with the exception of the holes that are plugged with dowel locating pins.  Make sure you install the mounting bolts on the right side BEFORE you install the dipstick; if you don’t, you cannot get all of the bolts in the center of the header flange installed, as the dipstick will be in your way.  As for the dipstick tube itself, NO modification is required when using the Jeal headers.  Simply re-use the spacer you saved, and install it between the dipstick mounting tab and the header flange.  You will have to install the dipstick tube itself from under the car, so you can get a good grip on it and guide it into the oil pan hole.  Make sure the plastic/rubber boot is on the end of the dipstick tube; it tends to fall off when installing.  And, make sure the dipstick tube is pressed all the way into the oil pan hole.

 

Once you have all of the bolts installed, you can install the oxygen sensors.  I chose to install these once the headers were bolted to the engine, but you could install the sensors while the headers are laying on your workbench.  I elected to replace the oxygen sensors with new ones.  Make sure you install them with the anti-seize lubricant that comes with them.  I don’t think the anti-seize lubricant was used on my original oxygen sensors, because I could not get one of them out of the original exhaust manifold (hence my decision to install new sensors!).  You will need oxygen sensor extension cables for BOTH sensors.  I had a new extension harness for the passenger side, but I ended up making one for the driver’s side as well.  I cannot see how you could make the original harness reach the oxygen sensors.  I found an AC/Delco parts warehouse locally, and I picked up factory weather pack harnesses and made my own extensions.  I also wrapped the extensions in head shield fabric, and tied it all down with plastic cable ties, up out of the way of the headers.  The sensor extensions came out great, and work well with the factory weather pack connectors.  A word to the wise; the connectors are NOT cheap!  It will cost you about $23 to make each extension if you go this route.  But it was worth it to me not to have to solder wire and use a factory looking connector.

 

The Jeal headers are supplied with a flange fitting for the left side, and a short collector extension piece for the right side.  The left side is a no brainer; just connect up the flange fitting and you’re good to go.  The right side took a bit of manipulating, but again, the Jeal headers are of such high quality that the collectors lines up PERFECTLY with the “S” pipes on my Corsa cat back system.  All I had to do was cut about 1 inch of material off of the front of the Corsa “S” pipe, and line it up with the right side header collector.  If you were to take the “S” pipe to a muffler shop and have them either crimp the end down, or enlarge the flange, you could slip the front end of the “S” pipe either into the header collector, or over it.  I ended up just butting it up against the header collector and driving the car, with basically one open header, 4 miles to the exhaust shop early Saturday morning to have the RT cats installed and everything welded up.  I cannot stress how well the Jeal headers are measured and built.  The job was made so easy by the quality of these pieces.

 

 

Random Tech Cats

 

I used the Random Tech bullet cats, which are about 9 inches long and 4 inches in diameter.  They fit well.  The are attached directly to the Jeal header collectors.  Originally I planned to have flanges welded to the Jeal header collectors.  I forgot to tell my welding guy to do that; consequently, he welded the RT cats directly to the Jeal header collectors, and the rear of the RT cats directly to the Corsa “S” pipes.  The upside is there are absolutely no leaks, and no gaskets to blow out (a VERY common problem with header collectors!).  The downside is I cannot drop the entire exhaust system from the headers back, but only from the front of the Corsa exhaust resonator.  To me, it’s not a big problem, as I don’t plan to drop the exhaust, transmission or engine frequently.  Just know that it could be an issue in the future if you need to remove any of these components.  In the end, I could remove the headers with the RT cat connected to them and get at anything I need, so again, I don’t see it as a huge issue.

 

The Results

 

To me, this is one of two “must do” items on your ZR-1, if you would like more power.  Coupled with a top end port and polish job, newfound power will be unleashed from your beast!  These modifications really “woke up” the engine.  I have more power up top, as well as noticeably more down below, and the sound is incredible.  No louder than before at cruise, but at WOT, you will have small children and women running for cover when they hear you coming.  The engine absolutely screams.  I also had a Marc Haibeck chip burned for my application, and it seems to work very well.  The only thing I would suggest to Marc, if it is possible, is to also disable the A.I.R. injection system on the chip.  I think the A.I.R. system is controlled by the ECM, and can be “turned off” by modifying the chip.  I solved the problem by removing the A.I.R. pump and all ancillary tubing and hoses entirely, resulting in a cleaner look in the engine compartment as well as the elimination of a VERY noisy component.  As it is, my Haibeck chip does the following (and maybe more that I’m not aware of):

 

            1.  Turns on both cooling fans at 205 F, and off at 200 F

            2.  Enables the secondary power enrichment system at start-up (power
                        key defaults to “on.”)

3.  Eliminates backfire through the headers on deceleration

            4.  Increases total timing by a few degrees

            5.  Eliminates the EGR system

            6.  Disables the CAGS system

            7.  Makes you bacon and eggs in the morning before you start this project
                        (I wish!)

 

The sum total of engine modifications to my car are as follows:

 

Port and polish of the plenum and injector housings, Jeal headers, Random Tech catalytic converters, Corsa exhaust, Mark Haibeck custom calibration, Mark Coplon air duct, Fluidyne radiator and 180 degree thermostat, and a gorgeous top end powder coating job in silver metal flake with hand painted lettering and cam cover emblems by Jeff Flint.

 

Stock dyno numbers were as follows:  327.9 RWHP, 326.1 RWTQ.

 

Dyno numbers with the current modifications are:  380 RWHP, 350 RWTQ.

 

Helpful Tools

 

Buy, borrow or steal every piece of extension, universal, socket and ratchet set you can get your hands on, in 1/4, 3/8 and 1/2 inch drives.  I made a trip to Sears to load up on extensions and ratchets I thought would come in handy.  Two other items that are extremely helpful are a short 10mm wrench (for removal of the stock exhaust manifold bolts), and a short 13mm wrench (for the installation of the new header bolts I used).  Also handy are universal sockets in 1/4 inch drive in 10mm and 13mm.  You will need a lot of driver extensions in order to reach many of the header mounting bolts from below the car.  You’ll be amazed at the pile of tools to sort out at the end of each work session.