New C4 Exhaust System - More Bark With Your Bite, Part 2 - Tech

Picking up where we left off... 

   

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Picking up where we left off last month, we removed the heat shield on the passenger side to allow for installation of the right-side header. This shield keeps exhaust heat away from fuel lines and filters. It required a little cutting after the header was installed in order to allow a sufficient air gap between the header and the shield.

You'll remember in Part 1, we removed the stock exhaust system from our '87 in preparation for an upgraded exhaust system that includes a gorgeous set of headers from Stainless Works, a high-performance catalytic converter from Random Technology, and a cat-back system from Corsa.

Removing the old system was no big deal. the only casualties were a couple of broken exhaust manifold studs, which we'll leave to whoever decides to restore this car 25 years from now. installing the left-side header was pretty straightforward as well, with a couple of minor complications such as having to make up a new rear alternator support bracket and stud, and accommodating a too-close-for-comfort fit between the header and the oil line that runs from the oil filter housing forward to the engine block.

Two of the three manifold... 

   

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Two of the three manifold nuts were so heavily rusted that the studs broke off, even though we had sprayed them liberally with penetrant. if we were going to re-use these manifolds, we would have replaced the studs and also used extra-long brass nuts made specifically for use on exhaust manifold studs.

This time we'll install the right-side header and the rest of the system. as you'll see, installing this header presented some interesting challenges that required a healthy dose of creativity and patience. In fact, we give high marks to the folks at Stainless Works for designing a header that fits where few other headers would dare to tread. It's just that the passenger side of the engine compartment was designed to accommodate assembly-line parts, and the original exhaust manifold was integrated into the design. Aftermarket suppliers, on the other hand, have to work within the space available and be inventive enough to design headers that breathe properly, while providing as much clearance as possible with other parts and systems.

the job was, at times, difficult and challenging, but worth the effort. The result is an exhaust system that has just the right sound and just the right look-subtle, yet serious-while affording ground clearance and decibel ratings that are just fine for a daily driver without being obnoxious. we also expect the benefits will extend to our next trip down the quarter-mile. We'll keep you posted.

We marked the underside of... 

   

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We marked the underside of the car at the rear edge of the catalytic converter flange. This allowed us to be sure the new system was in the proper fore-and-aft position to ensure proper alignment and positioning. Here, barely visible, is the hose clamp that holds the A.I.R. tube in place on the passenger side as seen from below. We're not sure when this clamp might have been installed when the car was built, but there's surely no way to get any kind of screwdriver on it or even a 1/4-inch drive socket, so we used a small box wrench to loosen it.

Parts List
Stainless Works
C48591 '85-'91 Corvette headers plus
Y-pipe/Thermalcoat
NBC250 (4) accuseal high torque band clamp
EBC250 (2) accuseal wide high torque band clamp

Random Technology
191-30001 high-performance catalytic converter w/accy's

Mid America Motorworks
628-096 Corsa exhaust system cat-back
603-930 catalytic converter hose kit
614-559 (2) muffler insulators

Local speed shop
ARP header bolt kit
Header gasket set
Local Chevy dealer
Dipstick tube

Tools Of The Trade
In addition to everyday hand tools, such as screwdrivers, wrenches, and sockets, you'll also need:5/16-inch, 12-point, 1/4-inch drive socket for header bolts
1/4-inch open end or box wrench for hose clamps for A.I.R. hose
Torx T-20 socket
Cut-off wheel
Improvised spark plug wrench

On the driver side is a coolant...        read full caption On the driver side is a coolant temperature sensor located between the two front spark plugs. this must be disconnected very carefully since this-like all the other plastic connectors in the engine compartment-have grown brittle with age and break easily. Happily, ours did not, but we were very gentle with it. The left-side exhaust manifold lifted out easily without the need to remove the alternator, just the rear support bracket. The gasket surface needs to be perfectly clean to prevent leaks. We cleaned the last of the gasket material off with an abrasive pad, but we left the spark plugs in and also plugged the exhaust ports in order to keep abrasive particles out of the engine.	No, we're not trying out for...        read full caption No, we're not trying out for the Olympic pole-vaulting competition; this was the only way we were able to remove the A.I.R. tube that runs back to the catalytic converter. Reinstallation was similarly awkward.	As shown in the previous photo,...        read full caption As shown in the previous photo, we had to disconnect the ESC knock sensor in order to gain clearance to put the right-side header up into place.
We were surprised to find...        read full caption We were surprised to find that the right-side header was such a snug fit that we had to remove the torque converter inspection cover and just about everything else in sight to find enough room to squeeze the header up into place. Yes, the starter had to come out as well. Since we knew this was going to be a pretty ambitious project, we had disconnected the battery at the beginning of the job so sparks wouldn't fly when we were working around electrical connections.	Trial and error taught us...        read full caption Trial and error taught us that we would not be able to install the upper bolt of the starter support bracket once the header was in place. we left it in place, but loose, so we could pivot the bracket as needed when sliding the header into place.	Here's something else we didn't...        read full caption Here's something else we didn't expect. There's no way the right-side header would go in without removing the engine's oil dipstick tube. We tried a mechanic's trick of using hose clamps, a piece of coat hanger, and a slide hammer with gripping pliers to try to extract the tube from above without damaging it, but to no avail. After several tries, we ended up using locking pliers and a hammer, knowing we'd ruin the tube in the process. We ordered up a new dipstick tube from our local Chevy dealer for $37.