Exhaust System

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The original system.
The exhaust system is always a hot topic.  At 1-1/4" in diameter, not only is it undersized and very restrictive for the 1275cc A-series engine, but it is a size no longer available at your local exhaust shop.
The original system can best be described as performance robbing, frail and problematic.  There is really no design consideration to absorb the rocking of the engine and therefore breaks and leaks are very common.  Modern front wheel drive cars employ either a swivel connection between the manifold and the header pipe, or a flexible connection positioned just after the header pipe turns under the firewall and straightens out again.  Many also employ motor mount configurations and/or top mounted engine stabilizer bars to control engine movement.
The America's system pipe diameter is far smaller than should have ever been used.  In fact, under hard acceleration, the tailpipe usually emits a whistling or hissing sound.  A dead give away of an overly restrictive exhaust system.   The smallest exhaust pipe diameter, and pipe bending equipement used in exhaust shops in the USA is 1-1/2" diameter.  So, there is no way to get the stock exhaust system repaired properly.
Here are pictures of the 2 systems that I've designed and had built for my car.  Both worked excellent and are a combination of the types of systems found on modern front wheel drive cars.  I have installed a top mounted engine steady bar, a flexible connection in the front exhaust pipe, and mounted the system in soft rubber hangers.  I've also done away with the original flared and clamped connection between the manifold and the header pipe.  This connection is a tremendous source of leaks and breaks.  However, I did try to replicate the overall design of the original system, in an attempt to keep a reasonably correct sound.
One word of caution on getting exhaust work done.  Stay away from the national chains that advertise lifetime warranty's.  Their corporate "Bean Counters" have figured out that the average person keeps the average car an average of 2-3 years.  Therefore, the quality of parts and workmanship they provide is commensorate with their beliefs.  The only guarantee you get is that you'll be back many, many times.
Go to a reputable local exhaust shop, especially the one that seems to do alot of work on the local custom car and street rod owner's cars.  These guys know how to weld and they know how to install a nice sounding and working system.  Get your exhaust done right the first time.  You won't regret it!
Exhaust manifold connection from above.

This is a view looking down the back of the engine from the right side (clutch side) of the carburetor.   You can see where the outlet portion of the exhaust manifold has had a oval shaped 2 bolt flange slipped over it and welded in place.  Your exhaust shop has these flanges pre-made in a variety of sizes and configurations.  We found a flange that had an inside diameter that fit over the outside diameter of the manifold.  It accepts a standard high quality exhaust gasket and has 2 bolts welded in place.

Exhaust manifold connection from right side.
Here's a second view of the flange connection at the manifold looking from the clutch side of the engine.  Please note the wide weld bead used to weld the steel flange to the cast iron manifold.  Yes it is possible to weld cast iron...if you go to someone who knows what they're doing.  Once the flange is welded in place, take a die-grinder and grind out the inside of the exhaust manifold's outlet to increase it's internal diameter.  Any improvement here will greatly increase the flow of exhaust gases out of the manifold.
The new exhaust header pipe will be 1-1/2" in diameter and have a matching 2 bolt hole flange welded to it.  Once mated to the manifold flange with a gasket in place, you will install nuts an washers from the bottom.  It is easy to reach from underneath when the car is on the exhaust shop's rack.  It is also easy to reach from above the next time you have to remove the manifold for any reason.  The best of both worlds.  The header pipe simply drops straight down at a slight angle to the backside of the axle flange.

Exhaust manifold with 2 bolt flange.

This is how the manifold looks with the 2 bolt flange welded in place.  Notice how wide the weld "bead" is.  The guy who welded this for me has a been a welder for probably 60 years.

Engine stabilizer bar.
This view shows the upper engine stabilizer bar that I added to my engine.  These bars were originally used on America's that came with automatic transmissions.  The bar has to be cut and re-welded or heated and bent, into an "L" shape in order to clear the clutch slave cylinder on the manual transmission car.  It helps if you install the breather that's pictured in order to clear the mounting bolts for the stabilizer.  I used polyurethane bushings that are available.  The mount is completely eliminates all engine movement, yet does not transfer any noise or vibration because it is mounted to the subframe.  It is a difficult job to mount the brackets that attach to the subframe because they were originally installed when the subframes were out of the cars.
View from front looking back
This view from the front looking back shows how straight the system is under the car.  There is plenty of room to run the front section of pipe down the tunnel on the right side of the remote shift housing, just like the factory did.  Keep the pipe up tight to the body by roughly keeping the center line of the pipe lined up with the bottom of the remote housing.  It won't hit anything that way, and it will look very clean, professional and stock. 
Once the pipe gets past the rear end of the remote housing, it can be curved into the center of the tunnel and remain in that position all the way through the mufflers and out to the tail pipe.
Bend at transmission.

This view shows the header pipe as it turns and goes toward the rear of the car. As the header pipe runs down the back of the engine, it passes to the rear of the right transmission output flange.  There should be a bracket at this location, mounted to the differential housing side cover using 2 of the sidecover bolts.  A standard horse-shoe shaped exhaust bracket can be used to hold the header pipe securely to the engine.  You must have this rigid mount at this location.

Flex piece installed.
Flanged joint at rear subfame.

The 2 pictures above show the system as I originally designed it and had it installed.  I found a woven stainless steel flexible connector on a Japanese car in the local wrecking yard.  This is a great source for these flex pieces because they are extremely expensive at the exhaust shops.  This flex piece was a bit too big, but the price was right and it performed well.  I would recommend using one of the smaller flex pieces like those used on the Mitsubishi's or Geo's.  Many of them are more like the size and shape of a slightly flatened baseball. 
Following the flex piece is a high quality glasspack.  It is 2" inside diameter,  4" outside diameter and 24" long.  You'll have a choice to turn the glasspack so the internal louvers face into the flow of the exhaust or away from it.  In otherwords, they will either scoop at the exhaust, making the system quieter, or be facing away from the flow, making it slightly louder.
Just after the glasspack is another 2 bolt flanged connection.  This is located just before the rear subframe and allows the tailpipe section to be removed so that the fuel tank or rear subframe can be dropped without dropping the entire exhaust.  It also allows the system to be replaced or repaired in sections that unbolt.
There is a soft rubber hanger located in the original position on the front of the subframe.  Make sure this is soft rubber and not one of the reinforced rubber hangers that look like a section of tire belting.  The system needs to be able to flex.   A second hanger is placed on the rear crossmember of the rear subframe.  It also must be soft rubber.

Front most rear subframe hanger.

This view shows the front mount on the rear subframe is simply 2 "L" shaped brackets welded in place.  One is welded to the subframe and the other is welded to the exhaust pipe.  These have flared ends where they locate in the soft rubber hanger.

Rear most subframe hanger.

This view shows the rear mount on the rear subframe.  This soft rubber mount has a bracket that bolts through the original mounting hole in the subframe.  The other end of the mount is bolted to a piece that is welded to the exhaust pipe.

Tail pipe view.
This view shows the tailpipe section.  The original system didn't finish angled upward as I've done here.  It came straight out the back, curved upward along the indentation in the bottom of the trunk (visible in this picture) and then it turned again and pointed staight and level, stopping about even with the face of the rear bumper.
If you choose to add a chrome tip, make sure the opening in the end is not a lip that rounds backward toward the interior of the pipe.  This lip is actually somewhat restrictive and can cause the system to whistle or hiss under acceleration.

New tailpipe section.

This is the newest change to the exhaust system.  After looking at all the factory brochures and other information while creating this page and offering advice to several others, I decided to have my tailpipe exit in the correct look and location.  The bends are shallower than the original configuration, but that keeps the exhaust flow from being restricted.

View of the completed system.
View from underneath.
This panoramic shows the exhaust as I now have it.  After we started taking longer trips to British car shows, we realized that one glasspack just wasn't enough to quiet the rumble of the exhaust tone.  It sounded great around town, but after about a half hour on the freeway, it was alittle much. 

I decided that with the upper engine stabilizing bar, which has urethane bushings, I no longer needed the flexible section in the front pipe.  I had the exhaust shop install a 3" outer diameter, 2" inner diameter, 18" long glasspack.  We then re-did the rear mounts in softer rubber to allow more flex in the entire system. 
This has really quieted the exhaust noise and rumble.  The other benefit was that the increased back pressure from the smaller front glasspack really improved the idle characterists. 
The only thing I would change about the system is to have flanges installed on the glasspacks.  They could be replaced easier and without welding, and it would allow me to switch their direction and expirement with what made the system quieter.  Glasspacks have rows of internal louvers.  Mounting the glasspack so that the louvers are facing the exhaust flow quiets the exhaust more, but impedes flow and vise versa.
If you would like larger versions of these pictures please email me.