Exhaust Systems on Sheepscot Kits

I have changed my mind about the best way to build an exhaust system. The use of a muffler/stack casting presents a few problems like shortening the muffler, drilling the bottom of the muffler to accept the exhaust pipe, and keeping the pipe and stack in alignment with a good glue joint.

We will now include green wire and styrene tubing on all our truck kits for use as both exhaust pipes as well as drive shafts. In both cases the wire can be bent and glued into a hole drilled into the bottom of the solid urethane casting. Adjustment is easy because the wire bends easily.

Also, it seems that no two trucks have the same exhaust system. Some under the frame, some vertical. New trucks had a better looking system than did a truck a few years old, fifty years ago exhaust pipes rusted through after little use and became weak and bent, were replaced by some weird looking parts.

The green wire supplied with the kit is easy to work with so you can cut the plastic tubing to the length of muffler desired, glue in place on the wire, paint it and then install it on the truck. Use the small wire for a gasoline engine, the larger for a diesel, either one for a drive shaft. Paint will make a difference, it will increase the diameter and if it is not opaque will make the part look larger.

Be sure to file the top of the stack flat and paint it black to give the impression it is hollow. The muffler can be fairly bright silver but the pipe should be more brown/rust coming through the silver, particularly at the bottom near the road dirt. The vertical muffler is usually, on an HO scale model, a muffler and a heat shield together.

When bending the pipe remember it bends easily and that means it is soft, so be careful about grabbing it with pliers with a square jaw.

All Sheepscot kits will have these parts in them so even if you don't use them on this kit you can keep them around for another kit that comes along that may need an exhaust.

Now the question on vertical exhausts about weather the exhaust pipe should come out from behind the cab under the frame or on top of the frame under the cab. This becomes more of a topic for discussion now that we�re producing truck kits of the 60s and 70s. If you�re interested in being specific about dating your truck models for your layout the following may be of interest.

As engines became more powerful a few other things happened. Engines got higher and as a consequence the truck hoods in many cases were redesigned and made higher and since the driver had to see over the hood the cabs got higher off the frame. At the same time engines were becoming super charged and turbo charged and the exhaust manifolds were becoming more varied and complicated. Rather than a simple manifold that pointed down toward the rear of the engine the exhaust pipe started at a higher point near the top center of the engine.

The result of these changes made it possible and desirable to route the exhaust on top of the frame. This started happening in the sixties with many trucks and it affects the Sheepscot Autocar trucks. Mack cabs have always been rather low and are mostly unaffected by what I have said above because when Mack designed the frame for the B series they spread the rails at the front about four inches to keep the hoods low and provide room for their V-8 engines. Other trucks had straight frame rails. Many manufacturers, as they changed their cabs in the 60s, changed their exhaust systems. Autocar made the change to their cabs in 1950 but the exhausts didn't change until the 60s.