Hey guys! I've been thinkin' for the past while that I want to convert the single exhaust I currently have to a dual exhaust system. My plan was to use the stock manifolds. I was reading that in order to use the stock manifolds I would have to block off the portion of the of the passenger side manifold where it connected to the drivers side manifold through the Y pipe. I've been reading the debates about the H and X crossover pipes and is an H or an X really nessecary? I dont plan on racing or anything just a nice throaty sound and better flow then the single exhaust system.

Can anyone reccomend a good dual exhaust system that would work off the stock manifolds?

I'm looking at this one now.(pg 64)
http://members.***.net/123webspace/catalog.pdf

Thanks,
Dan

 

lol , I blocked the extra port off with a small can that once had tomatoe paste in it , and a clamp ( only temporary of course but its been holding up good for a year now ) when my exhaust came down I just bought a couple of cheap turbo mufflers and a piece of pipe from Farm & Fleet , some clamps a 90 degree elbow , some flex pipe for the tail pipes.....it has a sounds pretty decent growl to it beleive it or not for only spending about $100 all together....but of course you will have possible exhaust leaks and not to mention it doesnt look to good , but if your looking for something cheap and temporary for awhile and dont weld or have a friend who does and or owns a muffler shop then here ya go , lol

 

not probably recomended though

 

no need for the H or X pipe unless you are trying to get every last HP gain. you can get nice dual exhaust manifolds from Thornton Reproductions which have both outlets at 2 1/4" (cuz your factory manifolds have 2.25" on one side and 2" on the other, which can cause some problems). i just got an aluminized dual exhaust system and bought the jones full boar mufflers seperately. if you want the manifolds, pipes, and mufflers of decent quality, you'll be in the $400-$600 range.

 

I forgot to add that the car is a '72 cutlass town sedan.

 

There are several companies that make a nice cast cover for the extra hole in the PS manifold. The H pipe will help bottom end torque and make the car a little quieter. The Thornton manifolds have a 2 1/4 DS and 2 1/2 PS dumps.

 

Would I need to get a different size pipe for the drivers side or would the exhaust shop be able to crimp the larger pipe down or somthing? Would I need to get the cast cover for the ps manifold or could I just inform the exhaust shop guys that they'll need to cap it off?

 

The exhaust shop makes the same size for both sides and just necks down the DS, on mine the stock manifolds where 2" on the DS and 2 1/4 on the PS. You don't need the cast cover but it will last the longest, most muffler shops will make you a cap out of your old pipe if you want.

 

@jag....I'm pretty sure the Thornton 350 JR's are 2.25 outlets on both side. The whole point of them fabricating and manufacturing these manifolds are for small blocks that want to go from single to dual. Also, they eliminate having 2 different size outlets, which is what u will have if you just cap the cross over inlet on the factory PS manifold. I just checked the Thornton website, it doesn't say anything about a 2.5" PS outlet. I've had my factory manifold capped now for a while, and have had nothing but exhaust leaks. From the capped crossover itself, and the factory 2" DS outlet going into the downpipe. Can't wait to get the thornton setup, personally. Much cleaner than ur old manifolds, and make more sense operationally. Plus, they have better flow than ur factory manifolds, as well.

 

I measured my set before putting them on, one side was 2.5 one was 2.25. Both side do use the large manifold flanges like the PS did originally.

 

Hi Dan! Calgary's not that far from Edmonton and there are a few CO members also in Calgary.
I have a 72 Cutlass S that has the stock 350L34 / 350 trans. I converted my single exhaust to dual by welding a plug into the crossover pipe exit on the drivers side. (This is also what GM did with the cars that were ordered with 350's and dual exhausts). I put in an H crossover and it seems to balance exhaust flow nicely and there's a nice rumble at low idle. Cost was minimal.

I thought about buying Thorntons new dual exhaust manifolds, but I'm not that impressed with them. I have a set of Hedman 350 headers (still NIB) that I haven't decided what I'm going to do with them.

The dual exhaust does allow the exhaust to flow better and does boost power a little. If you're just looking for a throaty sound, why not throw in a Flowmaster or similar muffler. For increased fuel economy, you could change to a 4bbl carb - it's a significant improvement over the 2bbl 2GC you probably have - and will definitely improve overall gas economy unless you have a heavy foot.

The Northern Lights Olds Chapter is having a Rocket Roundup at Hildebrandt Motors in Olds (not too far from Calgary - nice day trip) on July 17 this year. If you can make it, we'd love to have you. You can take a look at my conversion and see if it's what you were visualizing before you do it to your car. For more info on the show, or to register/join follow this link: http://www.oldsnorthernlights.com/

PS: I don't like BAP; they have ripped me of twice. There are other aftermarket suppliers. Do you need a list?

 

Allan, you'll miss the show if you go on the 17th. It's July 16 this year. The caravan will leave Deefoot Mall at 9:30 am Saturday. You can find all sorts of suppliers on our website too. Go to the links page.

If you have single exhaust now, you'll probably want a transmission dual hump cross member. (In red, it points to one side of the dual hump - see how the exhaust pipe goes under the hump - it's the same on the otherside)
71Olds442153_40312632_thumb-1.jpg


Here's a picture under my dirty car. See where the exhausts go? This is a 17 year old non stainless exhaust system with Walker Super Turbo Mufflers.

I'd just take the car to a reputable muffler place in Calgary and ask for duals. See if you can find a dual hump cross member and get some nice sounding Dynomax or whatever you like. It'll sound great! JMO

 

Oops, I meant the 16th!! Did you mean DeeRfoot? Or has Calgary expanded to the point where they have Deefoot and Deehand malls?

In 1972 I believe ALL Cutlass chassis were built with dual exhaust crossover humps whether they had duals or not. I just checked my car and (no surprise) it has a dual hump crossover member. Otherwise I don't think you could put duals in. Dan, get a flashlight and look under your car. I'm betting the setup is already there waiting for an install.

 

that doesn't make any sense to me, why would they have 2 different size outlets?? i mean, obviously, noone would be running 2 different size pipes. so how did you accomplish a tight seal with your setup??

 

Because there isn't enough room on the DS I guess. I measured them what do you want me to do take a polygraph? One was 2 1/4 the other was 2 1/2.
Why does Oldsmobile make 2 different sizes??

 

Oh I'm not saying ur lying, I'm just asking the question...why would they do that?? It doesn't make sense. And I'm asking seriously, how did u connect your downtubes without any leaks? I use a donut on the factory 2" side and it leaks.

 

No! I meant Deefoot...oh alright. This pick and poke type is a pain in dee azz.

Whatever you do, dont Google "dual hump tranny crossover members". I bet nothing car related will pop up...either on the comptuer or in front of it.

 

Different sizes of exhaust -

http://sweet-thunder.com/chambered_u..._starfire.html

 

Oldsmobiles don't use donuts, they have the donuts cast on the end of the manifold, if it leaks you may need to take it apart and clean the rust out of the connection.

 

well that explains why I couldnt find a donut gasket for my 72 CS

 

Leaks on an Olds are usually caused by rust or the pipe is corroded away at the ball connection, at least that's what I have found.

 

More reasons for me to buy new ones I guess!!!

 

Thanks for all the responses guys! I think what ill do is go into the muffler shop and ask them for duals and see what they can do. I've been meaning to join the Northern Lights Olds Chapter but have not gotten around to it, Is there more then one Oldsmobile round up or cruise a year? I'm going to be out of town for this years. Also, Its already got the 4 bbl carb.

Can anyone estimate what the average cost would be using the stock manifolds for the exhaust shop to install duals?

Dan

 

Mine cost $500 with Magnaflow mufflers.

 

Muffler shops are a crap shoot when it comes to pricing. I went to Midas to get a new hanger installed around my wifes muffler on her Saturn. Got quoted 40-50 bucks, got charged 88. I was upset. Shop around, get your quotes (totals) in writing including all charges before you decide. Most shops will try to sell you their house brand muffler and pipes. Ask what kind of warranty you'll get also. You will also probably get asked what diameter pipes you want. Since you're not running a drag car, go with standard. I put in a crossover pipe on mine, that's up to you though.

When I did the exhaust on my 98 3 years ago, a single exhaust (with muffler, cat, pipes and hangers) from the EM back ran me 550.00 at Speedy

They probably have a generic plug to weld into the stock manifold.

When you get this conversion done, your car will simply breath better. DONT expect a huge jump in power or you'll be disappointed.

 

Murray's Minute Muffler on 17th Ave + 52nd St SE.They will give you the straight up advice and do the job right to your specs and budget.

 

mine cost me 50 bucks, but I work at a muffler shop