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76 DeVille Exhaust Manifold Gasket

Started by mgbeda, February 13, 2014, 07:48:38 PM

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mgbeda

I hope to get the exhaust manifolds back on Bessie's engine this weekend.  I've had them planed and sandblasted (and will soon paint them).  I'm wondering whether I should use the exhaust manifold gaskets (that came with the engine rebuild kit) or not.  I know they didn't originally come with gaskets, but my gut feeling is that gaskets are an improvement.

My big question is will I lose points in judging if my car has exhaust manifold gaskets?  That's the only reason I might leave them out.  Any Class 25 judges out there?

Thank you,

-mB

-Mike Beda
CLC #24610
1976 Sedan DeVille (Bessie)

Aprules2

I don't know much about judging, but I know I installed them on my last 75 Deville and they never leaked again.

By the way when I had my resto shop we did an engine bay restoration on a 56 ford. We sandblasted the exhaust manifolds and as a test i sprayed half the manifold with some POR 15 Cast Gray and let it dry. You honestly couldn't tell the difference between the bare cast and the spray. We ended up doing all the cast parts with that and so far its been 3 years the owner drives the hell out of it and the paint looks like it did when I put it on. You do have to thin the paint quite a bit before spraying it. We used the POR 15 thinner and thinned it out to something about the viscosity of Milk. Then sprayed 3 thin coats. They looked great.

I am going to do an engine compartment restoration on my 75 please put up some pictures Id love to see what its supposed to look like.

Scot Minesinger

Cut the gaskets so that they do not protrude beyond mating surfaces and they will not be very noticeable.  Rather have proper function in a critical area such as this rather than a factory correct look that produces a poor mechanical result.  Function before form.   
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

35-709

My '73 Caribou got exhaust manifold gaskets when I re-assembled the engine --- First in Class P25 at the Boston GN 2013.
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

If you had them surfaced they should be fine without gaskets.  I have only used them when I was not able to get the manifolds surfaced.

This era tends to run on the lean side which makes for some very high exhaust gas temps which I suspect is very hard on the gaskets.  Guessing that was one reason they maybe didn't use them at the factory.
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

"Cadillac Kid" Greg Surfas 15364

Because of their exacting manufacturing and assembly policies and tolerances, Cadillac was able to ensure NEW engines had near perfectly flat  cylinder head (at mating surfaces) and exhaust manifolds.  They assembled them without gaskets using an even and exacting bolt torquing procedure.  Once all the parts were "seasoned" by years of heat cycles, some warping was anticipated, thus the gaskets were provided, rather than the preospect of re-machining the manifolds, the heads and re-assembly with new bolts.  It was meant as a practical solution to repair.
Over the years I have re-assembled 70 era motors without gaskets successfully. As far as judging, chances are now that you have mentioned it, it will be a future line item in the rule books.
Geof, I hear tell that there will be several Caribou, Mirage, Paris type trucks that are surfacing and will be at the GN in Las Vewgas.  Should be interesting.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
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-

35-709

Hi Greg,
At this point in time we plan to be at the Lake George GN this summer and I know of at least one Mirage that plans to be there.  Lost Wages is a little far for us to travel but who knows what will happen by the time that show rolls around.  The Mrs. does want to go to the 2015 GN since she is originally from Wisconsin so we may get to that one.  Looking forward to seeing your Paris.
Regards,
Geoff 
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

35-709

Quote from: TJ Hopland on February 16, 2014, 08:47:54 AM
This era tends to run on the lean side which makes for some very high exhaust gas temps which I suspect is very hard on the gaskets.  Guessing that was one reason they maybe didn't use them at the factory.

Someone else will have to tell us just when, but Cadillac was not using exhaust manifold gaskets long before the '70's era.  For the reasons Greg Surfas stated, I would not reassemble the exhaust manifolds to the engine without the gaskets but it has been done.   
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

R Schroeder

Geoff, I hope the snow all melts by the time you get here in 2015. At the rate it has been coming down , it may never go away.
At least all the people in Wisconsin feel that way right now.
Roy

35-709

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

INTMD8

Personally on a thick flange manifold or headers with 1/2 thick flange or more I do not use a gasket, I use Permatex "the right stuff" gasket maker.  A very thin smear on clean surfaces.

Once ran in you can remove the manifold bolts and it will take considerable force to remove the manifold from the head.

-If- the gasket blows out you can have a rather large area for leakage the thickness of the gasket.

-If- the sealer blows out (which I've never had happen), you still have a very close fit between the parts.

Just my opinion!

35-709

I have used both copper hi-temp silicone and the gasket together.  Some don't think that even the hi-temp copper will withstand the heat but it will.  A thin coat is also used with the gaskets on aircraft exhaust systems with good results.
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

Glen

I put a coat of antiseize on the manifold so that it will slide as it heats up and cools down.  If it can not slide the manifold tends to crack.  I only have trouble with leaks at the exhaust pipe connection. 

Glen Houlton CLC #727 
CLCMRC benefactor #104