Author Topic: 1972 Eldorado Exhaust Question  (Read 301 times)

Offline boseephuss

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1972 Eldorado Exhaust Question
« on: January 03, 2018, 02:39:37 PM »
Howdy!

I have some leaks in my exhaust on my 72 Eldo vert and am looking to get the system replaced.  I am thinking of going the dual exhaust route, and thought about getting a set on the CAD Company headers while I was at it.

Does anyone have any experience with this system?  They are running a special on their headers currently and thought if nothing else, might give it some extra grumble.

I have read a few posts regarding dual exhaust, but any other tips or info there would be appreciated.
J. Sims
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Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #1 on: January 03, 2018, 04:30:03 PM »
G'day Justin,

Tip No. 1   Go for a complete Stainless Steel system.

Reason. -  In steel, a single system lasts longer than a dual system simply because the components get hotter, faster, and this removes most of the rust and corrosion-forming contaminants, simply because there is less material to heat up.   Plus, the less you use the car, the faster it will rust out.

Tip No. 2   Stay with cast iron exhaust manifolds.

Reason -   As there is very little room to create a good tubular manifold for the Left side of the engine.   Plus, if the engine is relatively stock, there is nothing gained from headers, except for looks, and added noise in the engine bay.   Yes, Headers are noisy.

These vehicles were designed for a Single system as the fuel tank is off-set to the Left and there is not much room for 2 pipes to pass under the central crossmember to retain good ground clearance.

I fitted a Stainless Steel dual system to my own '72 Eldo, and had to be very creative to get it all to fit.   I worked with the Exhaust maker and it took a fair bit of designing.   Oh, and it did cost more than expected.

I had to perform a couple of flattenings in the area of the crossmember to allow the pipes to be closer to the body, and it worked well.

Over the rear axle, there is also a clearance issue with the ALC linkage.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline boseephuss

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Re: 1972 Eldorado Exhaust Question
« Reply #2 on: January 03, 2018, 05:39:19 PM »
Thanks so much!  These pictures are excellent and I appreciate the advice.  I take it the juice was worth the squeeze?
J. Sims
CLC Member #48960216

Offline bcroe

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1972 Eldorado Exhaust Question
« Reply #3 on: January 03, 2018, 05:51:54 PM »
Duals were popular for reducing back pressure in the past,
because it was easy to add a second mirror image pipe on
the other side of the car.  However, one large pipe with the
total cross sectional area of the 2 smaller pipes will actually
work better.  If everything is going to be custom down a
single available channel, a big single pipe might be
considered.  Bruce Roe

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #4 on: January 03, 2018, 07:48:50 PM »
Thanks so much!  These pictures are excellent and I appreciate the advice.  I take it the juice was worth the squeeze?
Not actually sure, but I have increased the gases out of the engine by higher compression, bigger valves and a warmer camshaft.   Oh, and increased carburation as well as modifying the air cleaner for improved breathing.

Yes, I am a hot rodder at heart.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline boseephuss

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Re: 1972 Eldorado Exhaust Question
« Reply #5 on: January 04, 2018, 12:14:18 PM »
Duals were popular for reducing back pressure in the past,
because it was easy to add a second mirror image pipe on
the other side of the car.  However, one large pipe with the
total cross sectional area of the 2 smaller pipes will actually
work better.  If everything is going to be custom down a
single available channel, a big single pipe might be
considered.  Bruce Roe

Yes, this might be the best option for me.  Thanks for chiming in!  Much appreciated.
J. Sims
CLC Member #48960216

Offline boseephuss

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Re: 1972 Eldorado Exhaust Question
« Reply #6 on: January 04, 2018, 12:16:22 PM »
Not actually sure, but I have increased the gases out of the engine by higher compression, bigger valves and a warmer camshaft.   Oh, and increased carburation as well as modifying the air cleaner for improved breathing.

Yes, I am a hot rodder at heart.

Bruce. >:D

I definitely want to give the ole gal a little bit of love and intend on investing in a bit more performance eventually.  Too fun not too!

The next thing on the agenda is making sure I don't have any collant issues (a fair bit of white out of the exhaust on last startup) and getting the suspension sorted.
J. Sims
CLC Member #48960216

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #7 on: January 04, 2018, 02:55:56 PM »
I forgot the most important picture.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline bcroe

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1972 Eldorado Exhaust Question
« Reply #8 on: January 04, 2018, 04:55:16 PM »
Thats pretty.  Were you able to use OEM hangers?  Some of
the cheap after market hangers I tried conducted vibration
and dropped the system on failure.  Went back to only OEM
types to avoid that. 

I should look to see if a dual muffler setup could work on
my 79 Eldo.  The 3 inch single I have is too small overall
to do the best job.  Is there a cross over pipe near the
engine?  Bruce Roe

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #9 on: January 04, 2018, 05:58:27 PM »
The third picture of the original postings above shows the cross-over pipe, and yes, I did use the OEM mountings, with modifications to suit the extra width where necessary.

It is heavy gauge Stainless Steel.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline TJ Hopland

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Re: 1972 Eldorado Exhaust Question
« Reply #10 on: January 08, 2018, 07:43:01 AM »
My plan with the 73 is to look at doing an oversized single system.  Its really tricky to get dual in and keep everything tucked up so nothing hangs low. 

A lot of stainless these days seems to be crap.   The good stuff is pretty expensive so be suspicious if someone offers both aluminimized and stainless and the stainless doesn't cost that much more.   I have talked to several people recently that only had them last 3-5 years.   I'm at over 20 now on a non stainless system and it doesn't have any rust issues, just poor design issues and damage from the poor design. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 1972 Eldorado Exhaust Question
« Reply #11 on: January 08, 2018, 11:22:24 AM »
Bruce's set up is the nicest dual(ing) an Eldorado that I have seen. If anyone wants to go duals that would be the way to go.  That said, in spite of the single exhaust seeming sufficient for most intended usages, when the Cadillac factory prepared their 73 Eldo fo the Indianapolis 500 application they did in fact go to a dual exhaust.  But, as Bruce said that was for a higher compression, hi-po camshaft high speed application.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #12 on: January 08, 2018, 09:14:29 PM »
Thanks for that Greg.

One thing I did when building the system was to use Flanges to connect the different pieces so that in the event of requiring to remove pieces to access areas, it would be an easy task.

Found this extremely effective when having to remove the engine, as without the removeable engine pipes, it is difficult to get the engine to join up with the exhaust when reassembling.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 1972 Eldorado Exhaust Question
« Reply #13 on: January 08, 2018, 10:23:44 PM »
An alternative would be the 6 inch SS clamps that I used on my system in my '73.  This lets me pull the exhaust easily for engine work.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #14 on: January 09, 2018, 01:00:59 AM »
A bit awkward with the Front Wheel Drive configuration.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 1972 Eldorado Exhaust Question
« Reply #15 on: January 09, 2018, 10:29:04 AM »
Just wanted to show the clamp joint.
Greg Surfas
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline The Tassie Devil(le)

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Re: 1972 Eldorado Exhaust Question
« Reply #16 on: January 09, 2018, 04:22:28 PM »
Ah ha.   I see what you mean.   

But, any clamping joint could twist in the event of it coming loose.   Yes, I know they don't, but they could.

One think I have found is that even Ford uses a clamped joint on their exhausts at the muffler, but they cunningly added a locating lug to stop any twisting.   It locates the muffler in the correct location.

Bruce.  >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline bcroe

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1972 Eldorado Exhaust Question
« Reply #17 on: January 09, 2018, 04:50:48 PM »
304 stainless really is lifetime.  Long ago I built one for my 79 Toro, ran
it a long time.  Then put it on the 79 Eldo for a while.  When a 3" went
on the (403) Eldo, some years back I sold it to a 79 Toro owner.  He is
still happily running it today. 

Those systems don't rust together, so you need to make sure nothing
is moving out of place over the miles.  I put punch  marks at every joint
to check on.  Hangers still wear out; the ones I use would rattle but not
drop the system.  Bruce Roe

Offline TJ Hopland

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Re: 1972 Eldorado Exhaust Question
« Reply #18 on: January 09, 2018, 08:06:11 PM »
I do really like the band clamps.  They hold way better than the U bolt ones plus don't crunch the pipes so you can adjust things or take them apart unless they rust.    IF you are clamping a flared coupling you don't have to special order the clamp with the flare in it the flat ones will contour to fit just fine.  They will also tolerate a slight bend if they have to.   I have also used them to patch holes.

Flanges are a great idea and something a good exhaust shop should suggest.   Even in the rust belt they seem to work good because you can just snap off the rusted bolts and replace them. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason