Oliver Gets a Cat (Part 2)

This is still not a children's story. Instead, today we finish integrating a catalytic converter into the Bell header-through exhaust system I installed onto our 1978 MGB, Oliver. Since my last post, I have learned that our Summer Solstice music festival, 4Peaks, is cancelled this year. While not surprised, this summer will be our first in years without a trip in Hapy to see some music. Yes, that is a total first-world problem and others have far bigger issues to contend with than some music festival. Gotcha. It is still disappointing for me, my fellow patrons, the vendors, the hosts, and the musicians. Anyway, where was I?

Pipes Arrive
I mentioned last time that I got a replacement section of pipe shipped from Britain. I measured, re-measured, etc that pipe and cut it into 3 pieces, 2 to keep, one to toss. After test-fitting those 2 pieces, I shipped them off to the ceramic coating company I used 2 years ago. The owner got the job done and the pipes shipped back fairly quickly. I had read that CoVid-19 can reside as an active virus on cardboard for up to 24 hours (and steel and plastic for up to 72 hours), so I set the box on the floor of my garage and let it sit for a few days. Once out of quarantine, they were ready to install.

Heat Shield

One of my biggest concerns about this whole project was how to keep the heat (up to 800*F) from cooking my legs on long drives. The MGB originally delivered with a heat deflector that was integrated into the floor, but mine was cut up as part of the floor replacement I did the summer after I got him. I looked into commercial heat shields, but they are awfully expensive and they are generic enough you need to trim them with snips, etc to get them to fit. Next, I looked into fabricating one with a few rectangular sheets of aluminum and a thin sheet of high-heat insulation. I constructed a fairly good model with cereal-box cardboard (one of my favorite modeling mediums), and was just about ready to take that leap when I found the HeatShield family of products. I decided that a known solution was a better choice than my experiment, especially when it came to temperatures that high. Their solution would cover 90% of the catalytic converter. This does not eliminate my concern about accidentally setting tall grass on fire if/when I parked on the side of the road or at a more rustic setting otherwise. Since the ride height of this sled is around 6 inches anyway, the honest truth is this car will not be going anywhere near tall grass. If I park off tarmac, it will still be where I can see the lifts and valleys of the ground.

Shield Assembly

cat hanging by one end

Once the heat shield kit had sat through a multiple-day quarantine, I unpacked everything and started putting things together. I wrapped the catalytic converter with the heat shield pad. These pads are a thick white fibrous material on the inside with a thick aluminum outer shell. At 10" by 12", it was just about the perfect size for the application. The catalytic converter is 11" long, so by wrapping the 12" side around the cat, I was left about a 1/2" of access to the ends of the cat for attaching to pipes. That orientation also left a gap about an inch wide running the length of the cat, which, based on the instructions, was about right. The heat needs to go somewhere, so a gap is needed (usually on the bottom) for the reflected heat to exit. The kit delivered with 3 stainless steel bands to hold the cover on. I installed one in the center to hold it in place while I installed into the car.

Into the Car

center resonator mated to cat

Once the cat heat shield was on enough for handling, I took the front pipe and fit it into the rear end of the header, checking the depth against the originally installed full-length pipe. Similar to the test fits, the cat easily slid over the rear end of that short pipe. I cinched down both pipe clamps, noting that the rear one did compress the edge of the cat around the pipe, and the cat was held firm (absolutely no wiggle). With the shield in place, the cat is now very close to the underside of the car. In fact, it may act as a vibration dampener, it is so close. I continued by adding the shorter pipe into the end of the cat. I did not clamp it down, however. Instead, I maneuvered the center resonator into place, sliding the front opening around the short pipe. I raised the tail pipe onto a short stand (an old car battery), and got the center mount aligned and bolted tight. With the center mount set, I could wiggle and twist the short pipe and the cat to exactly where I wanted them. Then, I clamped everything down snug.

Center Support

basic exhaust hanger added

I wanted an additional support for the exhaust. The Bell system does not have any mounts between the front of the headers where they bolt to the head and the support behind the center resonator. This is a long stretch of unsupported pipe already and one that I wasn't thrilled with when I installed it 2 years ago. Once you add a 5 pound catalytic converter, there is a real threat of the system sagging, and potentially failing, given enough time. So, directly behind the cat, I added a $4US exhaust hanger. This will take the weight of the catalytic converter plus any hang from the front of the center resonator. I tightened the hanger just enough to take up the weight and be snug, but not enough to pinch the pipe.

Finish Up
Once supported, I re-tightened all of the clamps and completed the attachment of the system at the tail pipe. Last, I returned to the heat shield around the catalytic converter, applying the other 2 stainless steel bands at the front and rear angled sections of the cat. Once snug, I snipped the ends of the bands. I hadn't expected it, but the final overall install is closer to the underside of the car than the no-cat header-back system was. I'm not sure what is really different, but the front of the center resonator is higher off the ground. Not complaining. Quite the contrary; just surprised when I expected the opposite.

Test Drive
I now have until the end of May to find a day that is both sunny and when Oregon DEQ is open. Because of CoVid-19, this might be more difficult than your typical late-spring in the soggy Pacific Northwest. That didn't stop me from grabbing Boo, dropping the top and taking a drive to bake-in the heat shield. April is what I call our "donut hole" month where we get nice clear days between the winter wet and the soggy spring. So, we got some gas (masks on!), picked up go food from our favorite Thai restaurant (Rama Thai) and drove home. Oliver drove like a champ. I think he's quieter with the cat than he was before I installed it. Of course, it has been a while. I have greatly missed driving the convertible around, having parked him since we discovered last Fall that there is a leak under the windshield on the passenger side when it rains. For a car living in the Pacific Northwest, where it kinda rains a lot, that's not a good situation. So, once this Summer turns to Fall and the CoVid-19 economic impacts have resolved, I know what I'll be doing on this car: pulling the dashboard and windshield to replace the seal. Knowing me, I'll probably want to do a bunch of other stuff while I'm there, like replace the scratched-up windshield glass and the dried out original surrounding rubber. Maybe I'll replace the foam/vinyl dash pad that's all cracked and gouged up. I don't know. Let's see where we're at when that time comes.

If you haven't talked to the elders in your world lately, consider they have lived a life of relative isolation in the US before CoVid-19. So, they could use a friendly phone call now more than ever. As always, thanks for following along. Be safe, be patient and please be kind--