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Exhaust Manifold Gaskets

Posted By 312YBlock 3 Years Ago
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KULTULZ
Posted 3 Years Ago
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Just for info; What about the Copper exhaust gaskets that were available some time back?  They were advertised in Y-Block magazine at some point in the  past.. 

  Paul


I had forgotten all about these.

THANX for the wake-up call.



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Ted
Posted 3 Years Ago
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PF Arcand (3/17/2021)
Just for info; What about the Copper exhaust gaskets that were available some time back?  They were advertised in Y-Block magazine at some point in the  past..

I use copper exhaust gaskets on the dyno and they do have a tendency to leak when the mating surfaces are not perfect.  The copper gaskets do not allow enough varying conformity to the surfaces and are simply too hard in which to compensate.  I have tried annealing the copper gaskets to soften them up but haven’t had much success with that helping.  But clean up is minimal and the copper gaskets do tend to last forever.


Lorena, Texas (South of Waco)


2721955meteor
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KULTULZ (3/4/2021)
IMO ...

My experience has been that the gaskets tend to promote the manifolds cracking and/or breaking more quickly due to the gasket separating the two and there being a greater heat differential between the head and the exhaust manifold. 

TED


Composite gaskets are asking for a failure. They allow different heat expansion rate (and expansion/contraction) between the two different components. If you are worried about a possible leakage, FORD offered steel shim gaskets with heat shields for later FYB truck engines (I think VICTOR still carries them).

Good quality hardware, thread-loc and possibly mechanical locks if you don't mind the non-stock look.

Again, IMO ...

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Ted
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Talking about the use of exhaust gaskets is analogous to talking about religion, politics, or the brand of oil that’s being used.  You can always count on a spirited discussion when any of these are brought up.
 
First and foremost, some form of composite exhaust manifold gaskets are typically included with engine rebuild kits although most factory engines come with just a metal to metal fit between the exhaust manifold and the head.   These composite exhaust manifold gaskets are not to be confused with some of the steel shim exhaust manifold gaskets included with factory industrial or heavy duty engines.  Because the composite gaskets are included in the gasket sets, most people feel obligated to use them.  In short, exhaust manifold gaskets do compensate for imperfections or warpage that takes place over time.  Removing an exhaust manifold for any reason does bring exhaust manifold deficiencies to the forefront and the gasket is the cheap fix.  The more expensive fix is machining the exhaust manifold and/or cylinder head exhaust surfaces to get those back to where they will seal again.  $20 for a set of gaskets or $150+ for machine work is usually the deciding factor here.
  
The question at this point becomes just how tight to tighten the manifold bolts when using a gasket.  It’s obvious that using the original manifold to cylinder head torque spec is not going to work as excess torque at the flanges with a composite gasket in place is going to deform the manifold and especially more so at the ends of the manifold as in the case for the Ford Y.  As has been brought up, fasteners with locking capability or lock washers helps where the bolts cannot be torqued to their stretch limits.  The key here is to not over-tighten exhaust manifold bolts when gaskets are being used.
  
But back to why the factories do not use exhaust gaskets.  I had this conversation with a factory engineer several years ago and while the factory uses all brand new parts where sealing is not an issue on a new engine, there was a problem with the temperature differential between the cylinder head and the manifold.  Using no gasket or a metal to metal fit allows part of that excess heat or temperature differential at the flanges to be redistributed back to the cylinder head casting thus allowing the manifold to run cooler and slow down the propensity for cracking at the flanges.  Whereas industrial equipment may run steady state for hours on end where a varying temperature differential is not a problem, an automobile on the other hand does see varying temperature changes at the exhaust manifolds which brings forth issues not seen on industrial equipment.  For an automobile, the amount of heat being put back to the cylinder head casting does not have a significant effect on engine cooling but does lower the temperature of the manifold just enough that cracking due to excessive expansion/contraction of the cast iron is minimized thus slowing down any propensity for cracking.  The hotter an engine runs, the more the problem.  While I don't have the data to back it up, I suspect engines in the lower latitudes or mountainous areas have more cracked exhaust manifolds than those where the temperatures are cooler or the engines are not required to run as hard (climbing mountains).
  
My own experience over the years has exhaust manifolds using gaskets cracking more frequently than exhaust manifolds fitted to the engines with no gaskets.  Some of this breakage can be attributed to the age of the manifolds while other breakage can be traced to over-tightening of the fasteners.  The exhaust manifold design itself can also be a factor and especially where end cylinders on the same manifold fire consecutively.
 
Feel free to shoot holes into any of this or at least take pot shots at it.


Lorena, Texas (South of Waco)


Hoosier Hurricane
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Ted, there is another possibility why the factory did not use manifold gaskets.  Cost.  Since new engines with new manifolds didn't really need gaskets, why spend the money for gaskets?  Did your engineer mention that in your conversation?

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312YBlock
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Years ago I smelled exhaust gas while driving my 55, it was annoying, you take someone for a ride “nice car but PU”. Fuel mixture not being an issue I bought EM gaskets as I could smell exhaust when I popped the hood. I installed the gaskets and being ignorant of any torque limitation I torqued them to factory specs. I first turned all the bolts finger tight and then followed the documented tightening pattern a little at a time over and over again until I was at spec, that was at least 10 years ago. These are the original exhaust manifolds with God knows how many miles on them. They don’t leak, they haven’t cracked. Ceramic coating the entire manifold including flanges will deflect heat away from the heads. Weather you ceramic coat the EMs or not, installing them without gaskets is a win win as the temperature of the EMs will be reduced either way. But hay, I enjoy a Manhattan with Luxardo cherries, others like Maraschino cherries, we can argue the cherries but know one argues the taste of what’s in the glass, bottoms up 🍸.




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2 cents from a new guy. I think Ted Eaton covered it all, except the cost factor, which was brought up by Hoosier Hurricane. Saving dollars-cents is the beans-counters job. Also, I believe no one has addressed intake manifold exhaust leaks. Were there intake gaskets with the metal sealing at the heat transfer ports originally used? Also how are the aluminum intake manifolds with the heat transfer ports holding up? Do they use the the metal gasket section for the heat trans ports and regular gasket material like the iron manifolds? One more, Headers, and which ones address flange leaks better than others. I have stirred enough and am out of ammo. Now on to the cooling subject!   1st Cav Man
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Since many questions are being asked and answered by experience; I believe Ted stated that the EM will be cooler if directly attached to the cylinder head by heat dissipation. If this is true with the engine running hotter? And is it better to have no gaskets after an engine has been shut down to cool?
The manifolds on my engine are not original to the car or engine and as far as I know the surfaces of either have not been machined. The outside of them are coated and I run the Best brand gaskets.
I also needed to add heat defectors to the master cylinder I add because if did not like the temp when I checked. The standard car did not have one and the Thunderbird did. I installed the Thunderbird one in a longer form and attached silver reflecting tape to the bottom. It did drop the temp of the MC 15*...Any thought are welcomed..

56 Vic, B'Ville 200 MPH Club Member, So Cal.
PF Arcand
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Cavman: If I understand your question re intake gaskets properly?.. Not sure originally on cars, but the Truck heat crossover hole, in the intake gaskets, I believe  had a restricted hole with a metal edging in it. They can be used on car engines to partly restrict heat under the carb..  


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HAD FORD WHEN THEY BUILT YBLOCK ENGINES USED DECENT MANIFOLD HARDWARE(THEY USED GARDEN VERYTY GRAD ATBEST 5
HARDWARE THIN FLATS. RESULT WAS THES ENGINES  WHER KNOWEN IN BC CANADA AS LEAKERS.
MY EXPERIANCE WAS CARS FORKLIFTS,LUMBER CARRIERS. TRUCKS MOSTLY INDUSTRIAL. THE BEST SOLUTION WAS GASKETS, PROPER GRADE 8 CAPSCREWS,HARDENED FLAT WASHERS(NO LOCK WASHERS) L/W WHER TO NAROW AND THE HEAT REMOVED THE SPRING. INDUSTRIAL GRADE 8 HARDWARE IS ELASTIC AND WILL STRECH WITH  HEAT CYCLES IF OVER TORKED  YOU LOSE THE  STRECH. MY FINAL PREECHING ON THIS  TOPIC EVEN THO ACTION ON THE SITE HAS SLOWED A BIT. I ENJOY THIS SITE SUCH A WIDE SCOPE OF INTELEJENT GUYS


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