Exhaust system

[jim77]

Im looking for pics and suggestions on exhaust systems that you guys have done or are going to do. I would like to do dual exhaust but have to buy crossmember. Would like to keep o.e. manifolds haven,t seen or heard to many good things about header fitment. Any suggestions would be appreciated.

[zodiacblue442]

Do a search for dual exhaust on this forum and you'll get a bunch of threads to read. Here are a couple:

http://www.73-77olds.com/forums/showthread.php?t=117&highlight=dual+exhaust

http://www.73-77olds.com/forums/showthread.php?t=2465&highlight=dual+exhaust

Good luck with your project.

[74grannysup]

Just for your info, I went from a perfectly fine single exhaust to duals, and about a month after The left side some how developed a crack in the manifold, so....

[zates]

Jim,
I went with cat back's with a couple of Thrush mufflers. The 76 sounds great. My goal is to keep the car as original as possible though.

[77442]

When you guys went with duals, did you keep cat converters? (well add a new one or two new ones). Or did you scrape them? Do these need cats anyway!:confused:

[Firethorne77]

When you guys went with duals, did you keep cat converters? (well add a new one or two new ones). Or did you scrape them? Do these need cats anyway!:confused:

Most states have laws on the books about if a car came with a converter, it must still have one installed.

That being said, check with your own state on the emission laws.

You always can do what you want, but it may end up not passing the annual inspection if your state has rigid laws on the old cars.

Obviously with out a cat, it free's up the exhaust a bit to breathe better.

[Firethorne77]

Im looking for pics and suggestions on exhaust systems that you guys have done or are going to do. I would like to do dual exhaust but have to buy crossmember. Would like to keep o.e. manifolds haven,t seen or heard to many good things about header fitment. Any suggestions would be appreciated.


Jim-

As Gary posted, there are a few threads on this.
On my '77 I have run two different styles of dual exhaust over the years.

1st being, we left the factory cross over pipe in, ran a single pipe back to a Y pipe, out with two mufflers.
She had plenty of power, but was very quiet.

2nd, back in '07, I replaced the crossmember with a dual hump from a donor car, capped the extra port manifold from the old crossover pipe, ran straight duals, magnaflow mufflers out.
Much louder. Maybe a bit higher back pressure with these mufflers, I can get the numbers off the mufflers.
Made a difference in the mid range acceleration with that set up.

Good luck with what you choose.

Just remember these Olds motors were smogged to hell and offer more in the highway/cruising dept than street light to street light. You'll get more mid range power on the exhaust change than anything.

[zates]

I kept stock manifolds and Y pipe, but installed a new cat with dual pipes and mufflers. It has a nice mellow sound. Again, my goal was to keep my low mileage car as stock as possible with small mods to make it mine. It's no screamer. But it runs like a top.

[mdkingsley]

If you want true duals you could get the crossmember and a set of W and Z manifolds. They are for dual exaust and came on earlier cars. I think they are being remade but not sure. If you get a used set take them to a head shop and get them reground so they will seal good. I have a set and are planning on using them when I put the 455 back in my car with duals.

[MrRocket]

I don't know if W/Z manifolds will work for you. I'm assuming you have a 350 in your car. The W/Z manifolds are for a 455 application only(big block). They may bolt up, but I don't know how they would work. If in fact you do have a 455 that's my bad and I will tell you that W/Z or X/Z manifolds are the best short of headers. They make manifolds for true duals, Thornton I believe sells them for a small block and a big block. I should throw out that I have a set of X/Z manifolds for sale and if the crossmember is still on the 73 parts car I have, I would have one of them for sale too.