The Stovebolt Site Forums The Shop Area The HiPo Shop Assembling my own exhaust.

I was tempted to say I was going to FABRICATE my own exhaust, but that would not be very correct. I plan to buy a 16 piece stainless mandrel bent 2.5” universal exhaust kit and then cut and assemble the pieces myself.

I’ve never done it before. Wish me luck.

My GM factory cast-iron exhaust manifolds are 2 inch with a donut connection at the bottom of the manifold. I have installed temporary anodized steel pieces about 18” long to direct exhaust down and under the cab. See picture.

Here’s my plan:
I will use about 6” or less of the 2” pipe off the manifold. Then a 2” to 2.5” adapter. Then 2.5” pipe the rest of the way. The pipe will stay at about the level of the lower frame flange until it needs to curl under the swing arm front bushing. Pipe then curls under and inside the swing arm and then goes straight back and up fairly close to the bed until it curls up again to allow clearance for rear axle travel.

I have a metal chop saw to make straight cuts in the pipe. I’ll weld when I need to but the kit pieces all have one end flared so the pieces can fit together like tent poles. I’m still undecided about the mufflers but nothing wild. I want my neighbors to stay asleep when I leave for work at 6:30AM. LOL!

Please share any wisdom you have.

You're deep into the "overkill' zone on pipe size. My 1970 Cadillac Fleetwood with a 472 cubic inch engine used one 2 1/2" exhaust pipe and muffler, and a single tailpipe the same size. The later 500 cubic inch engine that Cadillac used in the late 1970's used the same syetem.
Jerry

So you think 2” pipe is adequate or do you recommend 2.25”?

I'm with Jerry. If it was a diesel, I'd say go big, but a gas engine doesn't need anything bigger than the manifold outlets.

2” all the way will be just fine.

2" will be plenty- - - -If you're running duals, it's also a good idea to put a crossover pipe ahead of the mufflers. Otherwise, the side with the heat riser valve runs colder than the other pipe and forms a lot of condensation. That can rust out a muffler and also cause one side to drip water, especially if the vehicle isn't run far enough to get the pipes hot every time it's started.
Jerry

That’s really pushing my skill level. I know about Xpipe and Hpipe setups but figured they were more for performance than I would require. I guess an H pipe wouldn’t be too tough.

Nothing fancy- - - -just a straight across pipe a little ahead of the mufflers. If you can install a T fitting in both pipes, you might want to have a muffler shop bend a crossover to clear the transmission tailshaft or driveshaft, depending on the location of the mufflers. Then either clamp or weld it into place as you assemble the system.
Jerry

Lugnutz Are you a heli-arc specialist ?? Wont you need to weld stainless at least some on your build ?? Bought a stainless complete system about 83 perfect fit,sounded great,still the same today,heli-arced mufflers were show quality .

Shoot no! I don’t even know what heli-arc is. I was just gonna MIG weld it.

These should work. They are 2” and a cross over can be clamped in place as you mentioned.

I did the headers on the Model A by fit, the rest of the exhaust I did with that neat little multi piece plastic tool. Which probably woulda helped a bunch on the header. 1.5" tubes in to a 2.5" system. The collector is a 1.5" x 2.5", Summit Racing item. Some might say overkill for a V6, but, it is a blown V6. Simple X pipe. Took some 45 degree tubing and sliced the corners off. Took my time, checked everything twice before tacking. So far I am just in front of the rear axle. I'll do the rest the next time I remove the body. Magnets help for holding stuff along with muffler clamp tools.

I'm sorry, the X-pipe was made with 2 90 degree pipes. The exhaust work starts on this page, about 1/2 way down the page. In case you wanted to follow along with what I did. http://www.bunchobikes.com/modela6.htm

Lugnutz In my area we have a lot of hi-powered welders a round a Marathon refinery. I learn from them. Your right you can mig it

Used to fab all my own exhaust as we work on a lot of orphan cars with no kits available. Long before there was the plastic kits to make a prototype I used defroster duct and filled it with foam so it would hold its shape to transfer to steel tubing. Picture of a 57 Studebaker Golden Hawk home made header. Tubes are large diameter to go with an engine with a blower. When the foam sets the tubes are very rigid.

[img]https://i.postimg.cc/PCNw1pyq/57-Golden-Hawk-Headers-016.jpg[/img]

[img]https://i.postimg.cc/qN9znmgm/57-Golden-Hawk-Headers-017.jpg[/img]

[img]https://i.postimg.cc/Z9t50CD2/57-Golden-Hawk-Headers-005.jpg[/img]

Evan,
The pictures were all blah, blah, blah to me until, with all of the patience and hope I could muster, I got to the last one. The picture of the Golden Hawk! I knew that you wouldn't leave me hanging. That car is one of my favorites.
I don't mean to downgrade the rest of your post. It was very informative. I just got distracted by the hopes of seeing a picture of that fine car.

I made a 2-1/2" for my 69 C60. I ordered a kit and cut off all of the slip joints and tig welded mine. I went all the way to the rear of the truck and pointed them straight down with a set of knock off 40 series Flowmasters. I also out in an H pipe.

I also made the exhaust on my 52 willys truck with a 460. 3" duals all the way back with an H-pipe. I'm running the same mufflers you posted a picture of on that. They have a nice smooth rumble with almost no drone. High rpms they are very loud.

A word of advice is to NOT put your mufflers under the cab. Put them under the bed. I've made multiple exhausts and always put the mufflers as far away from the underside of the cab as possible. If there is any drone from the exhaust it will resonate under the bed and not into the cab.

On a old school gasser, changing the pipe size only changes the noise. Smaller pipe is much more snappy sound. larger pipe is deeper growl.

In college I had a 429 with 2" all the way. Very cackley.

Another thought on this. I have always thought the H or X pipe made the SB sound worse. My 95 Impala SS was a true dual exhaust from the factory. NO X or H. Once I removed the muffler but kept the small resonator it was the best sounding engine I has heard in a long time. I can't speak to the weird cross over intake putting more into one side or the other, but I do think H's and X's take away from the unique traditional sound.

I’m finished. Sorta.
All the pipe is hanging. Some is just tack welded, but safe to drive with. I’ll finish it up soon with complete welds.
Lots of twists and turns. The X-Pipe is there too.
I bought Magnaflow glasspacks. I got the shortest ones they sell.

Here’s a VIDEO.

Here are my thoughts.
I won’t attempt this again. I’ll pay someone. My main enemy is time. I have very little free time.
I’m also overly ambitious. So I bite off what I can’t chew sometimes.

I thought that having mandrel bent pipe would be an upgrade but in the end it won’t matter. I needed the muffler shop to expand a few pieces for me, so there were 6 or 7 times I had to stop the assembly until I had time to swing by his shop.

The good part is that I probably have a more user friendly exhaust layout than what a muffler shop would have done. I want to hang a spare tire under the bed so I had to be creative about swinging the pipe outside the frame.

The final step will be to make a 2 bolt flange connection on the straight pipe about half way back along the frame so I can remove the exhaust in pieces if needed.

Maybe a V-band joint? That way you'll never have to worry about failing gaskets. I little more expensive but longer lasting. Extremely easy to weld in.

I like the idea of a V-band joint. I’ll check it out. Thanks for the tip!

What do you think about this type of connection?
LINK HERE

I'm not a fan. They like to leak after a while. I'll use them for mocking up a system, though.

Those band couplings have two drawbacks :

Butt-ugly
Prone to loosening up and leaking

I like the old fashioned slip joints where one pipe is expanded, and another one slips into it, particularly where the muffler(s) are attached. It makes changing a rusted-out muffler much easier, and doesn't compromise the flow through the pipes the way some other methods of joining exhaust system parts can do.
Jerry

I’ll likely install V-band clamps. With the X-pipe, all of it must come out at once UNLESS I provide some way for the pieces to separate. The 16 pieces in the universal kit all had expanded ends for a slip together fit which was nice during mock-up.

I'd weld it in place and cut it if you ever have to remove it. What's the likelihood of that? probably never.

I installed an exhaust system on my Cadillac in 2001. It came as yours did with slip fittings and clamps. I had every joint welded. It's had over 100,000 miles on it since then and I've never had to remove it for any reason.

There are no leaks, rattles, squeaks, or loose clamps to tighten. It looks a lot better, too.

You'll only regret fully welding it if you have to remove it!

On my '55, they welded it straight under the axles. Worked great until you had to change a tire and they had to cut my exhaust!

I'm going to do my own exhaust and will be using v-bands for a couple strategic breaks so I can easily maintain my truck for years to come.

Best of luck!

Why would the exhaust pipe be in a position that prevented you from changing a tire?

Most new cars are welded from front to back. Replacing Cats. and mufflers requires cutting the pipe and either welding in the new part or clamping it in.

How often is it necessary to remove any exhaust parts to do routine maintenance? Lugnutz is completely restoring/modifying his truck. I doubt he'll ever need to replace the muffler in his lifetime let alone take the exhaust system out.

Otto, the problem is the pipes were mounted "UNDER" the axle.

The pipe from the manifolds goes straight back along the rails. Then they each swings towards the centerline to make an X-pipe. Immediately after the X-pipe, the 2 pipes straddle the drive shaft and travel up to the glasspacks under the bed. So far, all of that pipe could come out as one unit . . . . BUT . . .
After the glasspacks the pipes swing outside the frame rail. It’s there that they become too widely separated to fit between the rear swing arms for removal. So when the time comes, either during my lifetime or someone else’s, the pipes will need to be jointed somewhere.
Since I can’t complete the welds while the pieces are installed, I’ll need to weld them on the bench. Reinstallation once fully welded would be impossible UNLESS I can disconnect it at a few places.

Yes, that's unusual but I don't see how it hinders tire changing.

Band clamps arrived today. Better quality than I expected. If the pipe ends butt against each other squarely, then I’ll use these immediately AFTER the glasspacks for the last section of the exhaust pipe.
As far as the “ugly factor” goes, they are tucked up under the bed far enough to stay out of sight.