Williamaronson

To those of you that know me, as well as those that don't...I am looking to replace the exhaust on my 1955 Oldsmobile 98 Holiday Coupe from single to dual exhaust (DE).

A friend with a 1955 Oldsmobile 98 sedan told me that in order to do this, I need to change one of the exhaust manifolds (driver's side?) to a 1956 because DE wasn't an option in 1955. I have found very little mention of this online and figured you guys and gals might know. He also told me that when he first changed his sedan over, he did not do it and caused significant engine damage as a result. Not one looking to damage my 62 year old engine with 71,000 miles, I need to get answers and hopefully get them quickly.

As always any help is appreciated, but I prefer accurate information.

Charlie Jones

William,
This is the gosphel according to Oldsmobile .
As written in the 1963 Oldsmobile Master Parts Catalog .

Group 3.601 Manifold Assy , Exhaust
54 thru 56 All .......R.H. .......... 563300
54 thru 56 All .......L.H. .......... 567569

As you can see , there is no mention of different single or dual exhaust manifolds .

I suspect that the problems your friend had , may have been due to a blocked or stuck heat riser .

Williamaronson

Thanks for the input.

Ozzie

My books agree with Charlie's numbers. Hence there was no manifold change in '56 for the dual exhaust option. There are many ways to achieve your goal. A bit of frame modification will be required. Here's one version of a kit.

http://waldronexhaust.com/cart/index...oducts_id=3147

I can't tell what part of the world you are in, but if it's more warm than cold, you can live without the heat riser. Sometimes it can be more trouble than it's worth.

TRWham

For 54-56 single exhaust, the LH exhaust crosses under the engine and enters the RH manifold and then runs back in one pipe through the frame from there. The dual system blanks off the front connection on the RH and each side runs back independently. The X member has holes on both sides for dual cars, but only one side for the single version.

redoldsman

I just had the Waldron Exhaust installed on my 54. I was surprised it was a perfect fit and required no tweaking. I bought the whole kit for both sides without mufflers. I will say it is a very close fit around the power steering. If you have power brakes you will have to use round mufflers like glasspacks (I used Smithys and love the mellow sound) since there is limited room between the vacuum tank and the frame. There was no dual exhaust on 54's and 55's so you will have to cut the x member for the exhaust and tailpipes. Duals were first available in 1956 and I believe all frame were cut on both sides whether they had duals or not which makes sense. The tailpipes will come out right under the bumper guards which is where the right one came out from the factory. There is no need to change manifolds. You use a block off plate on the front of the right side manifold. If your current exhaust is good you can probably get Waldron just to sell you the pipes for the left side. They do not have the kits on the shelf and make them as they are ordered. There is about a 3 week lead time. It is not a cheap conversion but man I love the way my car sounds.

TRWham

Yes, I have heard reports that the '56s are all cut, but for cars prior to '56 they will need to be cut.

Tedd Thompson

What Redoldsman said.... But any style muffler can be used if you move the vacuum tank to the outboard side of the frame. this gets it out of the way and it can't be seen from out side of the car. There are other ways to get around the muffler problem if you are having a shop custom bend your exhaust but they will hate you forever, it is a very tedious job.... Tedd

redoldsman

I just about guarantee you a custom shop will charge you more than you will pay for the Waldron kit and as Tedd said, they will hate you and your car. I was very impressed with the Waldron kit. I put some header wrap on the section of the pipe where it passes by the power steering. I didn't think about moving the vacuum tank and probably would not have anyway. The only complaint I had about the Smithys mufflers is they leaked a little bit along the seam. I put some muffler putty on them and it sealed them. I put some Brockman Mellow Tones on it at first and it sounded like it had open headers. I took them off after two weeks. They were well built but not mellow. I used 30" Smithys which gave me that deep mellow tone I was looking for. These old Oldsmobiles really sound sweet with a nice set of glasspacks on them.

Tedd Thompson

That is nostalgia at its best. When I was young it was Smithy's or Cherie bombs. No wonder I can't hear anymore.... Tedd

redoldsman

I wanted period correct and Cherry Bombs are too loud. I know the Smithys will get a little louder as they burn out some but right now they are perfect. When I am driving with the top down I can't get the smile off my face. If I shift into Super and let off the gas it talks to me. I put the duals on, installed a new set of Coker radials and had the transmission rebuilt and it is like a different car. Sorry I didn't intend to steal this thread.

Ozzie

The guys at the frame shop must have kept busy. The Olds parts book shows 5 different frames for 1954; 7 different for 1955; 7 different for 1956. Each year was unique unto itself. As you could imagine 98 is longer than 88 & S88, but one was 88 & S88 with 2 or 4 door sedans & Holiday coupe; another was 88 & S88 Holiday sedan; another was S88 convertible; another was 98 Holiday coupe; another was 98 Holiday sedan; another was 98 convertible; and another was 98 4 door sedan. Nowhere was there mention of single or dual exhaust so I assume that in '56 the frames' web holes were there for either exhaust configuration. Unfortunately such was not true in '55. Hence you will need to duplicate the frame's web holes on the driver's side to add the dual exhaust. I did it without much grief on mine.

chopolds

Did my 55 '98' with an available kit, back in 1982 or so, with real Smitty's from the 50's. I did have to modify the front left pipe to fit around the power steering, as it was a VERY close fit. And yes, you'll have to cut holes in the X member for the pipes to run through.

Williamaronson

jozw30

Tedd Thompson

I'm not sure why your muffler guy would be afraid of a hole in the X frame when there is a matching hole through the same frame 3 feet away. That frame is huge and twice as strong as any Chevy frame of the same vintage. My advice would be to go to another independent owned shop and ask them to do it. I'm sure your muffler guy is more afraid of his corporate lawyer not the strength of the frame..... Tedd

redoldsman

In 1956 both sides were opened up since that was the first year dual exhaust were available. When I put the duals on my 54, I took it to a hot rod shop and had them cut the frame. I now have a plasma cutter and would do it myself. Tedd nailed it pretty good.

Williamaronson

redoldsman

I am not familiar with the different grades of stainless steel. You are paying a lot extra for stainless. When you consider how little you will probably drive the car you will probably never burn the aluminized steel out. I looked at the diagram of the exhaust and it probably looks like it is for a car without power steering. I would not pay that for it. You can always send the seller an email and ask him if it fits a car with power steering. If he says it fits both then it is time to rum. Your car, your money.

Williamaronson

redoldsman

Good luck with them and let us know how they fit.