Before I even ordered my MkIV base kit last November, my plans were to build a street version roadster with smooth hood, full bumpers, glove box and street-style gauge layout, no roll bar and under car exhaust. So far, the biggest challenge has been the exhaust system since it has to be fabricated from scratch. Wanted to post some pics on the progress I have made so far.
What I thought would be the easiest part of the build, the headers, turned out to be the most frustrating. The FFR manual references two shorty headers (Ford Racing and MAC) that will fit my 351W-base engine and clear the oil filter and mechanical fuel pump. I ordered a set of the MAC 351W swap headers from CJ Pony Parts and was immediately told there would be a 6 week wait while MAC manufactured the headers. When I followed up on week 6, I was told that MAC hadn’t started on them yet so I canceled the order and with the refund ordered a set of BBK 351W swap headers from Summit Racing. They arrived in three days but unfortunately the rear tube on the drivers side hit the inner footwell panel. Thought about making a recess in the panel but the tube looked like it would also hit one of the 1" square tubes. I considered having the header tube cut but since the headers were ceramic coated, really didn’t want to do that. After posting my situation, got a response that the Ford Racing swap headers would fit but they had been out of production for a few years. I was extremely lucky that I found a NOS set on eBay for $200. I was very relieved when they fit perfectly with absolutely no interference.
Now that I had the starting point for the system, I concentrated on the pipes and mufflers. I purchased some straight oval pipes, low profile mufflers (2.25" tall) with oval inlets and some oval connectors from Spin Tech. The oval pipes are 1.75" tall which will provide the greatest amount of ground clearance. I also bought a selection of tight turn 2.5" u and j bends from Summit Racing along with a pair of header connectors. Started by cutting the slip-on ends of the header connectors off so I would have a short piece of 2.5" pipe to weld onto one of the 90 degree j-bends (all joints are welded - no slip joints except into mufflers). I then fitted the muffler under the seat pan and held it into place with some wire while I fitted the oval pipes. Although Spin Tech makes a straight oval to 2.5" round pipe connector, I made my own. I cut a 5" piece of 2.5" round pipe, inserted a plug in one end to keep it from collapsing while I squeezed the other end in a vise to get the oval shape. With a little work with a body hammer, it was easy to get the oval shape to match up exactly with the oval pipe. To maximize the ground clearance, I used a 90 degree vertical connector to get the pipe turned up before I added the straight connector. Although not absolutely necessary, if you change from oval to round pipe under the car, you defeat the purpose of using the oval pipe.
Once I had the oval pipe in place and exiting in front of the footwells, it was a matter of figuring out the correct angles and lengths and cutting the pieces out of the u and j-bends. I spot welded all of the joints until the section was completed and yes, I did have to take it apart several times and refit. I bought a handful of stock exhaust pipe hangers from the local auto parts store and used the pieces and some flat bar stock to make hangers to hold the mufflers. I made a double hanger for the pipe in front of the muffler and a single one at the very rear of the muffler. The bottom of the mufflers is the lowest part of the system and sticks ½" below the bottom of the 4" main chassis rails.
I plan to use black exhaust wrap around the pipe under the car to help control heat into the floorpans. Still deciding on whether to get the entire system ceramic coated or paint with a hi-tem exhaust coating since most of the pipe will be wrapped (will definitely have the headers ceramic coated).
Still have plenty of work to do but I think all of the difficult work is done. For the pipe over the rear end, I think I will take the flexible metal radiator hose/pipe that came with the kit and bend it into the shape I will need and take it to a muffler shop and have it bent. There are just too many bends for me to cut and weld together for that section. I will have to wait until the body is fitted before I add the tail pipes but that should be relatively easy.
In terms of cost, I estimate that I will have close to $1,000 in the complete system including the headers but not counting the cost of ceramic coating. Definitely more work that installing a set of side pipes but I didn’t have to deal with some of the issues with the body cutout and header alignment. It was a fun and challenging part of the project.
Will post Part 2 when I get the rest of the system completed.
Thanks,
Ron
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