[Teej]

I'm chasing some exhaust leaks at the connections and have been considering putting dual exhaust on it while I'm in there. But I'm getting confused....

On this page it shows the '55-'59 Engine Assembly with the drivers side manifold going forward and crossing over in front of the engine.
http://www.pontiacsafari.com/MPC/Pages/page_0048.jpg

On this page it shows the Head, Manifold and Related parts (Typical 55-60) and also has the front cross over that my '58 has.
http://www.pontiacsafari.com/MPC/Pages/page_0052.jpg

But on this page it shows the '59 single exhaust as routing behind the engine.
http://www.pontiacsafari.com/MPC/Pages/page_0178.jpg

I've posted a thread in the exhaust section and have found a company that offers a dual system for the 58,59,60... I'm just not sure they are the same.
http://forums.maxperformanceinc.com/...d.php?t=714534

Which years cross over in front and which cross over in back. I know the '58 crosses over in the front.

[PONTIACSOUTH]

I am planning on putting real duals on my '58 too. there is a elbow that came on the factory dual exhaust 58 ponts, might of been bonne's only. you need this elbow or i think the drivers side exhaust manifold needs to be changed to a '59 and up manifold. these elbows can be bought from ames or on ebay for about $88 or so. Lucky i have a '58 bonne engine laying around with one of these elbows im going to steal and use on my '58 super chief.

[jmt455]

Yes, duals require that casting.

These guys can also make the exhaust system, but not the adapter.

www.waldronexhaust.com
(800) 503-9428

[PONTIACSOUTH]

Luckily my '58 came with dual stainless exhaust on it already. the seller removed the 454 n trans that was in it and left the exhaust.

[Teej]

Well, I ended up talking to the guy from the e-bay posting in the other thread. Classic Exhaust up on Geneva Ohio. I saw a couple posts here from some satisfied customers and he seemed to know what he was talking about. He said that for the '58, he includes that bend (100 degree +) in the headpipe. I had picked up one of the elbows a while ago, but he says that I won't need it with his pipe.

I also liked that he didn't flinch when I said my '58 was a wagon. He said that he has that pattern as well.

So, I ordered the set. I'll post my results when I get it installed.

[PONTIACSOUTH]

Teej, do you still have that elbow? If you're not going to use it i might be able to use it on my other '58.

[Antique]

Not sure this helps. I know for a fact that a 60 two barell from the factory routes arround the back. I had a 57 with a 60 389 tri-power and 60 auto installed and I had Midas convert to duals but was just a kid back they so don't remember the routing.

[Safari Larry]

Originally Posted by jmt455

Yes, duals require that casting.

The duals do NOT require that casting. They require that casting for stock header pipe but a good "pipe shop" can make the bend in the pipe without the casting. Here is a 56 exhaust manifold with the dual exhaust elbow installed. 58 looks the same but internal ports are slightly larger.

[Teej]

Antique, yes it does help to have a confirmation of at least one of them. So I know '60 runs around back and '58 runs in front. Rumor has it that '59 is around back too, but the manual links above don't seem to specify each year.

PontiacSouth, yes I still have the elbow. Once I get my system in, if I'm happy with it, I'll gladly sell it to you for what I have into it. I think it was only $50.

But while you are on board, tell us about your '58s... And post pictures. I love to keep in touch with other folks with '58s.

[jmt455]

Originally Posted by Safari Larry

The duals do NOT require that casting. They require that casting for stock header pipe but a good "pipe shop" can make the bend in the pipe without the casting. Here is a 56 exhaust manifold with the dual exhaust elbow installed. 58 looks the same but internal ports are slightly larger.

True.

I should have clarified my statement...duals require the casting if you want them to be the same as the original "stock" design.

[Safari Larry]

Thad, 1955-58 driver's side exhaust manifolds exit to the front to allow for routing around the steering box. 1959 and later driver's side exhaust manifold exits center. So header pipes and crossover routing is quite different between 58 and 59. The MPC pages you are looking at show the 1955-58 exhaust manifold and pipes. 59 is not the same.

[Teej]

That's about what I figured, but thanks for the clarification.

Why would they put "Typical 55-59" or "55-60" when there were signifcant differences?

[Safari Larry]

Originally Posted by Teej

Why would they put "Typical 55-59" or "55-60" when there were signifcant differences?

I can only guess why. The basic engine looks the same for those years but much of the stuff attached to it is not the same, including the exhaust, generator mounting, transmission, intake manifold, carb linkage, air cleaner, etc. The V8 engine illustrated was probably the first one they made (1955) and they continued using it for later years (thus "typical") as the MPC evolved. In 1960 reverse flow was discontinued and the basic engine had a different external appearance so they developed a new illustration for that year. Making illustrations for each year would have been time consuming and expensive in those days -- and it would not add much value to the MPC.

The primary purpose of the MPC illustrations was to find the Group number for finding parts in the listings and the illustrations serve that purpose quite well. The MPC was used by the parts personnel and was not generally available to mechanics (I was a mechanic in two Pontiac dealerships 1962-63). It was not meant to show how a Pontiac was put together and configured -- but that's what we often use it for today. It is a valuable document to us but it has its "warts" and is not perfect.