The whole deal worked out pretty well, all in all. The biggest problem was figuring out how to support the exhaust pipes under the car. On a traditional exhaust arrangement where the pipes run all the way to the back of the car, it is usually easy to fit some exhaust hangers under the floor boards somewhere back under the trunk. But trying to tuck the exhaust pipes under the floorboards with a side-exit arrangement means that it can be difficult to find enough room to fit an exhaust hanger between the exhaust pipe and the floorboard. If you hang the pipes low enough to fit a normal-sized hanger between the floorboard and the exhaust pipe, then the pipe hangs way too low. I tried to do what I could to get a couple hangers in place to provide some support, but it never really worked out very well. The glasspacks and exhaust pipes ended up being essentially cantilevered off of the ends of the headers. Despite the lack of exhaust hangers, the arrangement lasted through a few more years of service before one of the pipes broke, probably due to a combination of rust and fatigue. Fortunately, the hangers that were on there kept the pipe from dropping off of the car completely, even though they hadn't been supporting its weight very well prior to the failure.
Anyway, I was not able to devise an adequate support system for the side-exit exhaust system at the time, and I want a side-exit exhaust on the Impala, so a better arrangement is going to have to be worked out. I have some ideas that might work, but the guys at the body shop say they have an exhaust shop they work with, and that the guy from the exhaust shop is a genius of exhaust installation, so that has me thinking that maybe I'll have that guy work his magic on the Impala. I'm sure the pipes he'll make will look better than what I would come up with, and I can also learn whatever his tricks are for supporting a side-exit exhaust system. But in the mean time, I needed to come up with at least a temporary exhaust arrangement to use for the cam break-in, and until a better system can be installed.
I had another problem before I could worry about how to hang the exhaust, though. The outlets of the headers were pointed into the transmission mount crossmember. I wouldn't be surprised if a professional exhaust shop could probably work around this in some way, but I was trying to get some kind of exhaust hung before it went to a professional shop. It's also possible that a solution to route the exhaust around the crossmember would create some restriction in the exhaust flow. That's not really a big concern in my case, but I don't like seeing sharp bends in exhaust pipes, just on principle. Anyway, I started looking at aftermarket crossmembers, to see if there were any that would give better clearance for the exhaust.
The photo below shows the exhaust outlets from the headers, and the crossmember is visible in front of them. It has two humps in it to clear the stock exhaust arrangement, but they are too close to the centerline of the car. The headers are set wider apart than the stock exhaust pipes would be by the time they got back to the crossmember.
The next photo shows just the passenger side exhaust outlet, and the overlap with the crossmember in the foreground is evident.
My first thought was to look for a universal crossmember, thinking that there probably wouldn't be anything ready-made to fit my application. I thought maybe there would be something with some adjustability built into it that I could use. I found one that looked like it might work, but when I looked around online I found more than one person saying they'd tried that crossmember, and it had so much flex in it that they could feel the shifter and transmission moving up and down when they went over bumps in the road. That didn't sound real good to me, so I kept looking.
To my surprise, I found a Summit-brand crossmember that said it would fit 1965 Impalas, and it looked pretty beefy. It was fabricated from square tubing and looked pretty stout. My concern was that the humps for exhaust clearance looked like they might still be too close together, and no measurements were offered on the website. There was a photo of the part, though, so I decided to measure the distance between the mounting bolts on my car, then measure that distance on the photo, and work out a scale multiplier to try to determine the spacing of the exhaust clearance features. It looked like the humps were larger than they needed to be, and I thought maybe my exhaust would just clear the outside edges. Well, I measured and calculated, and it turned out that it looked like my exhaust would actually be pretty well centered in the openings. Looking around online, I didn't find any negative reviews of the part, so I decided to order one.
The photo below shows the aftermarket crossmember (top), as compared to the stock crossmember (bottom).
In that photo, you can see a hole in the top of the stock crossmember, toward the right hand side of it. That is where a hook for the parking brake cable is supposed to mount. The aftermarket crossmember doesn't have that feature, so I drilled a hole in the aftermarket crossmember in about the same spot, as shown in the photo below.
The photo below shows a close-up of those holes for the parking brake cable hook. The section of square tubing that the hole is drilled in is totally enclosed, welded on both ends, so I drilled another, smaller hole in the bottom of it to allow any water or moisture that gets into the top hole to drain out the bottom. The inside of the tubing wasn't painted or finished, so I tried to slop some POR-15 in through the hole on the top, to provide some corrosion protection on the inside. Probably an ineffective waste of time, but I already had the can of POR-15 on hand, so ... why not.
Next thing was just to install the crossmember, which just bolts into place. The photo below shows the new crossmember in place, and the exhaust outlets have a clear path to the back of the car. In the middle of the photo you can see the jackstand that I used to support the transmission while the crossmember was out of the car.
A close-up of the passenger side exhaust outlet, showing it pointed through the hump in the crossmember:
And one more picture, which I took to show ... something ... I assume. I don't know, it's been a while. I really need to get caught up on this blog.
So the next thing was to work out the actual exhaust piping. I just wanted something kind of rudimentary in place so as not to irritate the neighbors during the cam break-in, and so as not to be too much of a nuisance on the road during test drives and when taking the car back to the body shop. I had already picked out some mufflers, and I had a couple of short turndowns left over from when I put headers and glasspacks on the Corvair. The plan was just to put those mufflers and turndowns in place and rig up some kind of support for them, and call that good enough as a temporary arrangement.
Glasspacks are pretty cool, but they are also pretty loud. I decided to put glasspacks on the Monte Carlo because my buddy Allen had glasspacks on his 1967 Galaxie with a 390 in it, and I thought it sounded great. And there were a lot of things I really liked about having glasspacks on the Monte, but there were also some drawbacks. I used to put in earplugs if I was going to be driving more than 45 minutes to my destination.
When I decided to put glasspacks on the Corvair, I thought, "It's just a little 164 cubic inch engine, how loud could it be?" Then one day after I'd ordered and received the parts, but before I had the car running again, I was sitting in traffic behind a Harley and it occurred to me, "That engine is not even half the size of the Corvair engine, and it is pretty loud." It turned out that the Corvair was pretty obnoxiously loud once it was running with the glasspacks on it. That was a lot of fun sometimes, but could also be a nuisance.
My buddy Jeff used to live in a condo maybe 50 yards from the railroad tracks, and one time when I went to pick him up, he told me when I got there, "I thought I heard your car outside about five minutes ago, but it turned out it was a train going by." Another time, my dad had to move the Corvair out of the way in the driveway while I was in the house, and when I heard him start it up, I was amazed how loud it sounded from inside the house. It sounded awesome, but it was a lot louder than I would have guessed it would be. I'd never heard the Monte Carlo from inside the house, so later I asked my dad, "Is the Corvair louder than the Monte Carlo?" He didn't even hesitate to think about it, he just said something like, "Oh, good grief, no." So, as much as I love the sound of glasspacks, I decided that for the Impala I would look for something a little quieter, for my own comfort, and out of consideration for my neighbors.
Oh, wait, I've got one more glasspacks-are-loud story: I once got pulled over in Burr Ridge and given a written warning for my car being too loud. After that I generally avoided Burr Ridge for about a year, until I had some business that took me back there. I was driving slowly through an outdoor shopping mall, just idling along and looking for the store I was trying to find. Being that it was Burr Ridge, the street I was on was lined with parked BMWs, Audis, Porsches, and so on. I was just driving at idle speed, probably even riding the brake, going slowly to try to read all the stores' signs. As I was slowly making my way down that street, I thought back to that time I got pulled over and received a written warning for a loud exhaust. I thought to myself, Man, that cop was crazy, this car is NOT that loud at all. And right as I thought that, the noise from my exhaust set off the car alarm of a BMW that I was driving past. OK, fine, so maybe the car was a little loud.
SO ANYWAY ... those are my stories about why I didn't order glasspacks for the Impala. For the Impala, I wanted something that was generally shaped like a glasspack (as opposed to a boxy muffler shape), and with a good sound, but not so loud. Another drawback to glasspacks is that over time the fiberglass packing from which they get their name will degrade and break down and blow out, and they will get louder as this happens. I wanted to try to get something that wouldn't degrade like that, so I started looking at Flowmaster products, because I thought that all of their mufflers used chambered designs without packing that could break down.
Trying to pick out mufflers can be frustrating because you don't really know what they sound like until they're on the car. There are videos online, but the odds of finding someone with the same engine as you, built the same way as you built it, with exhaust pipes routed the same way as yours, and all the same mufflers you're interested in comparing are not good. And even if you did find that, a video just can't really give a good sense of what they'll sound like in person.
After looking through some information on Flowmaster's product line, I picked out the "Hushpower HP-2" muffler. Flowmaster has a graphic that arranges their products in order of loudness, and the HP-2 falls somewhere in the middle of the range, maybe towards the louder end of the street/strip section. It's also supposed to be the loudest of their mufflers that have an elongated shape instead of having a traditional boxy muffler shape. I like that look better, so it was a factor for me.
I had looked at some information online and I thought that what I saw was telling me that Flowmaster's products are all chambered designs, but eventually, after I'd ordered the HP-2s, I found out that their elongated muffler designs do use a packing material which can deteriorate. That was a little disappointing, but I already had the mufflers by the time I learned that, so I decided to just go ahead with them. If the packing deteriorates and they get louder than I want, then I guess I'll have an excuse to try something else.
Putting all these parts together would be relatively simple, but I still needed to figure out a way to support the pipes. I was especially worried about leaving everything cantilevered off of the headers because the engine now has aluminum heads, and I'm always worried about pulling the threads out of bolt holes in aluminum parts. I would eventually come to realize that the exhaust manifold bolt holes in the Edelbrock heads actually come helicoiled from the factory, which is nice, but probably still better to support the exhaust somehow.
Looking around under the car, I considered a few different options for rigging up some temporary support for the exhaust. I ended up deciding to try to use the bosses for the seatbelt mounting bolts. The bolt holes pass through the floorpan, so if I mounted the seatbelts with long bolts that extended under the car, then I could use the extra length of the bolt as a stud to mount a bracket which could support the exhaust.
To make the brackets, I bought a length of one-inch wide, eighth-inch thick steel, took some measurements under the car, cut the steel into two smaller lengths, and bent those up into two brackets with the shape shown below.
There is an empty hole for mounting the bracket to the car, and then there is a hole at the top of the bracket, with a carriage bolt installed in that hole. The head of the carriage bolt will butt up against the floorpan of the car, which should prevent the bracket from pivoting around its mounting point. Probably overkill, but that's kind of how I design things, I guess.
The brackets install in the driveshaft tunnel, so I was a little worried that they would interfere with the driveshaft. With that in mind, I tried to cut the bolts as short as I could so they wouldn't extend into the driveshaft's space any more than they had to. It appears that everything will fit.
The photo below shows the brackets mounted under the car, looking forward towards the transmission. You can also see the exhaust pipe lengths mounted on the reducers and running towards the back of the car.
The next photo shows the same view, but with the mufflers and turndowns installed.
And the last photo, below, shows the same arrangement, but viewed more from the side. After the photo was taken, I bought and installed six muffler clamps to hold it all together.
