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76 Eldorado exhaust manifolds and system

Started by 76eldo, September 21, 2010, 07:24:49 PM

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76eldo

I am about to have a custom dual exhaust system installed on my 76 Eldo.

There are one or 2 missing studs on each head/manifold connection.

I can remove the header pipes and would like to do the manifolds myself, and have some questions.

1.  With the manifolds removed, can I get a drill in there in case i need to drill out the remnants of the bolts?
2.  Is there a gasket?  If not should i install a gasket?
3.  Replacement bolts, should i use stainless or just match up grade 8 bolts.
4.  Is there a kit for this?

Thanks in advance for any answers from someone who has already done this.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

The Tassie Devil(le)

G'day Brian,

I fitted a custom made set of Dual Exhausts to my '72 Eldorado Convertible, and I used the original Exhaust Manifolds.   Want pictures?

I am pretty sure that to get any drilling fixture into the area whilst the heads are still on the engine, in the car, it is going to be virtually impossible, unless you have access to some really expensive right-angle drive drills, and then the holes have to be re-tapped.

You cannot use Studs as it will be impossible to install or remove the Manifolds.

The best way to go is to ure good quality bolts, and apply an Anti-seize compound to the threads.   Not sure about using Stainless steel Bolts, as the Torque Specks will have to be modified to take into account the different streaching features of both metals.

I don't believe the original manifolds were used with Gaskets.

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)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

76eldo

My choices are to leave the manifolds alone, as there is no leak, or to fix the broken bolts.

If there is enough sticking out of the head to grab with a stud puller or vice grips (ugh) I can get them out.  If they are broken off flush, then I have to pull the heads?

This car runs so sweet, you can't even feel it idle. I really do not want to take the heads off.

??????????????????????

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

35-709

I have always been told to use gaskets if you do pull those manifolds, eventhough Cadillac put the exh. manifolds on without them for many years.  When new everything was machined, clean, and mated perfectly or nearly enough so it worked OK.  That is no longer the case with a used engine and manifolds.  Exhaust manifold gaskets are supplied with rebuild gasket kits.  I would use them and have always done so.  As Bruce said, when reassembling the manifolds to the heads (if you go so far as to pull them off) use anti-seize on the threads.
Geoff N.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

TJ Hopland

You do not want to break any of the bolts.   Drilling them out in any car is very difficult.  There are a couple on the eldo that may not be that hard to get to but you know that those will not be the broken ones.  Gently rock them a bit and if it does not seem like they are going to move best thing is to get someone with a torch to burn the heads off so you can get the manifold off then use the torch to heat around whats left of the bolt with a vice grips again gently rock it back and fourth till it comes off.   

I would not use grade 8's.  The times I did that I had issues and someone told me that they are too strong and dont let things expand properly.  The one time it did work I used a stack of lock washers because I could not find the exact right length and Im guessing that added enough spring to keep things happy.

If you are doing a quality repair I would spend the few bucks it takes to have a shop 'surface' the manifolds.  They basically drop them on a belt sander so its cheap and fast and will help em seal up.   If you have the head done and the manifold done I would do it with no gaskets.  If you are not going to get either surface done then for sure you want gaskets. 

Make sure you talk to your shop about the dual system and how its going to look before the start working.  These cars were not designed for duals so it can be difficult to get everything tucked in so you cant see it and not end up with issues.   Its also worse if you want it to be nice and quiet because the mufflers are larger and you may need resonators.  A nice custom single system is a much better fit and can perform as well as most duals but dont sound the same if sound is what you are going for.  Just be sure to talk it over first so you dont end up paying twice what you expected for an ugly system that catches on things all the time like I did.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

76eldo

That's great advice.  The shop i went to said they can do it.  I have questions because the fuel tak is offset to the driver's side, and that leaves room for the muffler and resonator on the pass side. I will go there before starting anything.



Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Glen

The original manifolds can not be tourqued down too hard.  As the engine heats up the manifold heats up faster and expands faster than the head it is attached to.  The manifold must be able to slide on the manifold as it expands and conversely as it contracts when cooling off.  If it can not slip on the head it causes stress and can crack the manifold.

The shop manual has the torque specs and material for the manifold bolds.  My ’68 Shop Manual shows these bolts are made of 280-M (grade 5) and are torqued to 35 ft. lbs.  I can’t imagine the ’76 is much different. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

35-709

I would definitely take Bruce up on his offer for pictures o the dual exhaust installation he did on his Eldo, it is a nice job.
Geoff N.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

bcroe

If there is a magic solution to those bolts, I would like to hear about it.  Two cases here meant getting the heads to a machine shop, to remove up to half of those broken off bolts.  I'm think if a 500 goes into my 79 Eldo, it will be with stainless steel studs & nuts to hold exhaust manifolds.  Better to remove the engine to pull manifolds, than to remove the engine to send the heads out to a shop.  Bruce Roe

76eldo

If I probe the holes with a small allen wrench I should be able to tell how much bolt is sticking out of the head even before i touch the manifolds.

I am asking this without looking under the hood right now but if i need to drill anything out, would I have lots of clearance for a drill if I remove the inner fender and wheel?

Bruce graciously sent me photos of his dual exhaust install.  It's a beautiful job and engineered brilliantly.

Thanks,

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

The Tassie Devil(le)

#10
You might just get the rearmost left side bolt, and the two front bolts on the right hand side.

The rest aren't directly accessible because of suspension components.

I have an engine sitting in a Chassis, and had a look at the one in the car, and to drill one needs a direct line to keep the drill at right-angles.

And even trying to lift the engine, without removing axles from the Diff probably won't give enough room.   Then, if you are going to Remove the Axles, or undo them, it would be easier to simply lift it up sufficiently to complete the task, but then, you are going to have remove the AC Compressor, or disconnect the Cooling and A/C Hoses which will require you to dump the AC Gas as well to get it high enough.

Pulling it out would also require removing the Hood, which is probably easier than the Inner Fenders.  Oh, the joys of a broken bolt.

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)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Glen

There is a definite process for removing rusted bolts.  It is rare to find this process written down anywhere; normally it is passed on Journeyman to Journeyman.  I did find it in this website. http://mgaguru.com/mgtech/universal/ut102.htm 

The most important part is the part where if the bolt moves a little don’t force it when it stops.  Back up and try again.  Keep adding penetrating oil and rock the bolt back and forth.  You will gain a little each time.  You may gain only a sixteenth of a turn each time but you will eventfully get the bolt out without breaking it off. 

If it is already broken that a whole ‘nuther story. 

Always use anti seize on the manifold bolts and the next time you need to take it apart it will be easy.

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

35-709

Hard to get a good penetrant in to the threads of those exhaust manifold bolts.  But here is a list of penetrants that I posted some time ago and their efficacy for loosening rusted nuts, bolts, and studs, perhaps this is a good time to post it again for those who did not see it or have forgotten about it.  Good luck Brian.

Geoff N.

Machinist's Workshop magazine actually tested penetrants for break out torque on rusted nuts.  Significant results!  They are below, as forwarded by an ex-student and professional machinist, Bud Baker.

*Don't forget the April 2007 "Machinist's Workshop" magazine comparison
test.*
**
*They arranged a subjective test of all the popular penetrants with
the control being the torque required to remove the nut from a
"scientifically rusted" environment.*
**

*Penetrating oil ..... Average load*

None ..................... 516 pounds
WD-40 .................. 238 pounds
PB Blaster ............. 214 pounds
Liquid Wrench ..... 127 pounds
Kano Kroil ............ 106 pounds
ATF-Acetone mix....53 pounds

*The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic transmission
fluid and acetone.*
*Note the "home brew" was better than any commercial product in this one
particular test. Our local machinist group mixed up a batch and we all now
use it with equally good results. Note also that "Liquid Wrench" is about
as good as "Kroil" for about 20% of the price. *
**
 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2