Monday, December 12, 2011

Exhaust System

 Now that the engine , transmission, rear end, radius rods - front and rear, radiator , grille shell, and body are set up and everything seems to look like it belongs and will work, it’s time to build the exhaust system.  The one thing to keep in mind when building the exhaust is clearance.  Next , how it looks on the car and does it flow smoothly and am I going to be happy with it.  The last thing is serviceability.  Can I repair this easily or will it become a major nightmare and project?  Before starting I always install the things that get in the way and provide the most challenges when it comes to clearance.  Remember that heat is always going to be a concern around the starter, oil filter , battery cables , brake lines, fuel lines , wiring,  the floorboards, and the steering box.  I have an old starter and oil filter I use on my mock up engine to get started when building  the exhaust.  It’s always best to start at the exhaust manifold or header that is going to be used.  I try to use mandrel bent 2 inch o.d. exhaust tubing but often I use muffler shop bent tubing where it is not going to be easily seen.  Mandrel bent is the same diameter throughout the entire bend; whereas, muffler shop is smaller through the bend and standard size on the ends.  I only use 45 degree, 90 degree and straight tubing just to keep every thing simple.  By cutting , turning and using a few basic tube techniques, I can wind the tubing in and out, up and down, and over and under to create a very smooth flowing exhaust system.  If a person doesn’t want to go this way, they can just take it to a muffler shop and have them build a custom one - bring your wallet!  I start with the 1/4 -3/8ths  metal flange bolted to the exhaust manifold and will usually start on the starter side.  This will usually set the depth or length downward for the exhaust and then I can match the opposite side accordingly. 

Next  I tack a 1 x 1” thin wall length of tubing to the top of each muffler - this sets the floor clearance ( allows air to flow over the top so that heat inside the cockpit is minimal).  Then I tack two lengths of 1 1/2 “ angle  iron to each muffler ( one at each end)  make it long enough to span the width of the frame.  These are used to adjust the muffler in and out, front to rear, and allows for angle placement inside the frame rails.  In other words, it allows the muffler to be place exactly where you want it and then either tack or clamp the angle iron to the frame thus securing the muffler in place.  Then do the same with the other one.  This one shows four pieces of angle, sometimes I use just two and tack each end of the muffler and then tack the angle to the frame.  Now that the mufflers are where I want them (held firmly in place)  I can now build from the header to the muffler and from the muffler to the rear of the car and I can build the rear exhaust mount from the frame to the pipe or to the muffler and everything will stay put.  It’s nice not to have to fight the muffler while I’m building the front and rear parts of the exhaust system.

This shot shows the set up for the mufflers a little better along with the pieces that I used for the front part.  There are two ways to work with the exhaust pieces.  The first is to fit each piece and tack in place and then butt weld when finished.  The second way is to take several bends down to the muffler shop and have them open up each end so that the 2” tubing will just slide into the other piece.  They will usually do this for free or very inexpensively.  This actually makes the adjustments quicker and easier and give a much more solid connection and more rigid after welding.  I will often use a combination of the two to achieve what I am looking for as an end product.

This is a picture of the rear exhaust with two 45 degree bends and the ends have been opened up to allow the next piece to slip inside. After I have the angle I need, I tack in place for future welding.  When routing under the rear end, I will allow about 1 1/2 - 2 “ of clearance between the housing and the exhaust tubing.                                                  

Here is where hanging the mufflers really pays off.  You can see how the pipes will exit the chassis and from here I place the rear hangers off the frame to the exhaust pipe or to the muffler depending on clearance , brackets , or personal choice.  Once the rear hangers are in place , then the angle iron muffler supports can be removed.  When the exhaust is complete;  welded,painted, and installed, then I will add chrome tips after the body is mounted so the tips can be adjusted to the end of the body.  These can be tacked or screwed or pop riveted or any combination I want.

 This picture doesn’t have anything to do with the exhaust system but it shows something I do with all of my cars.  Notice the flat bar brackets coming off the frame.  These are for a removable trailer hitch.  There is another one on the other side of the frame that is hidden in this picture.  I make these out of 3/8th x 2 “ flat bar with a 3/8ths “ hole drilled for the removable hitch to  bolt to.  I may never build the hitch and yet if I need to or decide to,  then the frame or mount is already in place.  The top hole on the center bracket is for mounting the frame to an adapter when I put the frame on two engine stands for final welding , finishing, and painting.

Current Project:1927 Highboy - The hard way!