Before pursuing a hard core exhaust project on the `59 Chevy, it's important to get the big picture and figure out exactly how to accomplish the job. It's not a simple deal using aftermarket stuff. On the contrary, the `58 to `64 Chevrolet requires some finesse in creating an exhaust system that works correctly. It's all about the X-Frame design. Allow me to explain...
One nagging problem I got with Big Daddy was the exhaust; the car had been drag raced for a number years and still had the big-tube racing headers installed. They did a great job breathing, but the shear size and length of the tubes caused multiple problems. Underhood heat was high, undercar clearance minimal, and oil drainplug access was sacrificed. In fact, the drainplug couldn't be removed completely because of a header tube running right in front of the hole!
After working with and around these things for a while, I decided that installing a more factory-type exhaust was the only way I would have a better system. Full size headers wouldn't work well on this car, as it sits 2" lower than stock. The simple act of carrying a passenger has the car scuffing the tarmac all day long. I considered stashing the Big Block in a corner and installing an L-82 350 - that thought lasted all of 10 minutes, because I LOVE Big Block motors and will probably always have one in this car. I considered Block Hugger headers, which have become popular with the Street Rod crowd; these would have been ideal for this application, given their ability to pass pipe in the smallest of places and close to the engine block. They also have an exit point that is closer to the stock small block manifolds that would have been available on the car. But when someone offered me a pair of 454 exhaust manifolds for FREE, I snapped them up and went stock instead.
The manifolds I got were from a `71 454 Caprice. Luckily they were "oval port" just like the heads on my `72 402. The collector was all the way towards the back of the manifold, closer to the firewall than the front of the car. If you've ever seen a "ram horn" off a small block, you'll understand that the collector drops straight down the middle of the manifold below the 2 middle exhaust ports. The 454 manifolds exit at the back of the engine, so the point where the exhaust system would begin is not advantageous.
Why is this a problem? Frame clearance primarily. Things aren't always easy with cars that sit on X-Frames. Rather than having parallel rails (which the exhaust would between), the X-Frame meets in the middle and has space for the driveline to run through. Because of the path of the rail toward that middle point, the exhaust system has to make a very tight 180 degree turn from the inside of the rail to the outside. This is accomplished with exhaust pipe that measures 2 1/4" OD or less. I am told that, if a person tries to bend a bigger OD pipe at this tight angle, the result will be a pinched pipe. Another bottleneck is the rear frame area where, according to a veteran exhaust builder, there is only enough room to run 2" OD pipe past the differential. Bottom line is that these cars were not built to run contemporary Big Block Exhaust!
So for me the resulting exhaust is described as follows:
- 454 Exhaust Manifolds w/2 1/2" collectors
- 2 1/4" aluminized pipe, turned 180 degrees from inside of frame rail to outside
- 2 1/2" aluminized pipe, following contour of rail on the outside of frame
- 24" Cherry Bomb glasspaks, 2 1/2" OD
- 2 1/2" aluminized pipe, exiting in front of rear wheels
- 3" aluminized tailpipes, angle cut NASCAR style
The sound is deep and mellow. The exhaust is toned well inside the car at freeway speeds, and cannot be heard by someone even two car lengths away with the windows up. I have seen underhood temperatures drop, and my neighbors are happier now when I fire it up in the morning. I initially experienced a drop in gas mileage, but attributed that to the inefficient nature of the factory exhaust manifold design. Turns out my carburetor on the way out and I got the mpg back when I switched to a fresh carb.
Small block cars are much easier to configure, because the stock path can be utilized stem to stern; Miss Ruby, our `59 Impala, had 2" factory exhaust, quiet factory mufflers, and factory routing all the way out the back. The 350 breathed just fine with this system.
Kurt Clark
Originally written October 02, 2001 Edited and updated for this blog