Ken Sogge

Straight 8 Exhaust Manifold

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I too have been victim to the manifold cracking gremlin.  Since I have been unable to find a replacement as of now, someone is attempting to repair it. THis process has given me time to clean, repair or replace everything associated with the job as well as do some research. I found the 1952 Buick shop manual and its section on manifold removal and replacement indicates the intake manifold used gaskets and the exhaust did not.  My engine by the number is from a 1948 Super, installed in my 1940 Super in 1960 or earlier. My manifold had the black gaskets on both intake and exhaust, and I do not believe the engine had ever been disassembled.  The gasket blew out initiating the job. On removal I discovered the cracks in the manifold.

 

My question is this, does anyone know if it is true that no gasket was used on exhaust?? It would seem that the absence of gasket on the exhaust manifold while the intake used  them would cause sealing problems or even cracking???  All gasket sets include intake-exhaust gaskets which leads me to believe they should be used. I have purchased a set of the copper clad gaskets and intake rings from CARS, as well as a set of Belleville Washers from McMaster Carr, the only supplier without a minimum order.

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From what I have been told and what I have read about this, the straight eights after a certain date in the 1940's were assembled with pilot rings for each intake channel and around this they slid a crushable very thin washer type of metal gasket.  The exhaust manifold surfaces mating to the head used no gasket at all but were coated with a special compound, described in the shop manual as a mixture of graphite and a heavy oil or similar substance.  The hot box, exhaust manifold and intake manifold were assembled and bolted together (just snug to allow some limited movement) using a gasket between the hot box and the exhaust manifold.  In this joint they also placed a steel ring.   There was also a gasket between the top of the hot box and the intake manifold.  Then the whole assembly was attached to the head using eight sided washers  or Belleville washers for each stud.  If you see an engine with bolts instead of studs be sure to replace them with 3/8" studs, coarse thread on the head side and fine on the manifold side.  

 The studs were tightened starting from the center and working toward the ends with about 15 lb-ft of torque on each.  Then re-torqued to 25 to 30 lb-ft.  then bolts holding the hot box to the manifolds were then tightened fully to about 25 lb-ft.   I have had to re-torque the stud nuts after a few runs at running temperature.

It helps to have the assembly planed flat on a machine or belt sander.   I have always used the copper clad gasket sets sold today,   I never tried the approach described above.   I did however coat everything, both sides of the gaskets with a mixture of graphite and 50 weight motor oil.

Joe  

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Gaskets Isolate the manifold heat from the block thus creating a greater differential thermal expansion between the two.  Buick continued the no gasket  practice into the 60's with their nail head V8's

 

Bob Engle 

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14 hours ago, Thomas J. Bianculli said:

I know this was an old post. however McMaster Carr does still sell the washers, and they seem to be the only company I could find without a minimum order. They are in Ohio, I am in PA, and I just ordered a pack of 1 dozen in stainless steel for $12.60 and I will have them tomorrow!!!

 

Let us know how much the shipping is.

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6 hours ago, Larry Schramm said:

 

Let us know how much the shipping is.

Hello Larry,  The total bill on my Amex is $17.87, just over $5.00 for shipping. They use UPS.  Had they used First Class  Mail it would have been cheaper.

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18 hours ago, Joseph P. Indusi said:

From what I have been told and what I have read about this, the straight eights after a certain date in the 1940's were assembled with pilot rings for each intake channel and around this they slid a crushable very thin washer type of metal gasket.  The exhaust manifold surfaces mating to the head used no gasket at all but were coated with a special compound, described in the shop manual as a mixture of graphite and a heavy oil or similar substance.  The hot box, exhaust manifold and intake manifold were assembled and bolted together (just snug to allow some limited movement) using a gasket between the hot box and the exhaust manifold.  In this joint they also placed a steel ring.   There was also a gasket between the top of the hot box and the intake manifold.  Then the whole assembly was attached to the head using eight sided washers  or Belleville washers for each stud.  If you see an engine with bolts instead of studs be sure to replace them with 3/8" studs, coarse thread on the head side and fine on the manifold side.  

 The studs were tightened starting from the center and working toward the ends with about 15 lb-ft of torque on each.  Then re-torqued to 25 to 30 lb-ft.  then bolts holding the hot box to the manifolds were then tightened fully to about 25 lb-ft.   I have had to re-torque the stud nuts after a few runs at running temperature.

It helps to have the assembly planed flat on a machine or belt sander.   I have always used the copper clad gasket sets sold today,   I never tried the approach described above.   I did however coat everything, both sides of the gaskets with a mixture of graphite and 50 weight motor oil.

Joe  

 

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Hi Joe, thanks for the info. I found the 1952 Shop Manual somewhere on the site and you are spot on with what they said. I was going to use Copper Permatex which retains some flexibility but now I may go with the factory method as you suggested.

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3 hours ago, Thomas J. Bianculli said:

Hello Larry,  The total bill on my Amex is $17.87, just over $5.00 for shipping. They use UPS.  Had they used First Class  Mail it would have been cheaper.

 

That is reasonable.  There have been others that the shipping has been more than the cost of the part(s).  Thanks for the response.

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21 hours ago, Larry Schramm said:

 

That is reasonable.  There have been others that the shipping has been more than the cost of the part(s).  Thanks for the response.

Hello Larry, I agree. In addition to that when I was looking for the washers some vendors had a minimum order like $150.00 or a minimum of 1000 pieces.

Bu the way, the washers did arrive last night as promised and should do the job.

 

Tom

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On 1/25/2011 at 10:23 AM, Mark Shaw said:

The primary reason they crack is that many don't torque them correctly and/or use a lubricant type sealer to allow the cast iron to move.

Spring washers were also used to allow expansion while minimizing torque increase. These special washers sometimes get lost and are often replaced with flat washers.

As a manifold gets older it may need to have the flat surfaces dressed up to seal properly. Most don't do this and simply use extra torque to make them seal.

One problem often leads to another....

I have just purchased a 1938 McLaughlin Buick the manifold was cracked and professionally repaired and installed just prior to me buying the car.  It does have an exhaust leak, and I was very intrigued to read this post about the use of Belleville washers, sounds like they were installed at factory, is there different spring tensions and torques for these or if I get the correct hole size are they all the same tension and torque?  There was no sealant used between gasket and block, thought I might try the belleville washers first and see if that eliminates the problem or would you recommend removing the manifold using the sealer and installing correct washers?

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Posted (edited)

The exhaust manifold must be able to move with expansion. It gets much hotter than the head and it WILL get longer and the ends WILL move out. Anything that restricts that motion will cause the manifold to break. That is what you need to pay attention to.

 

The belleville washers just allow the manifold to move. They go on so the outer edge contacts the manifold and the inner edge contacts the nut. Soft washers could crush down and stop the motion.

 

Also pay attention to the studs and imagine the exhaust manifold getting longer. The manifold will probably hit the outside of the studs cold (to make sure the manifold won't hit the inside of the studs when it grows). If it is already hitting the inside of the studs and has no room to grow longer, you will need to do something about that.

 

Make sure the surface of the manifold is straight and flat. If it wasn't already warped, it probably warped when they welded it. Hopefully they milled it afterward, but if they didn't that could be why it leaks.

 

I don't know what sealer you refer to. You don't want to glue it down. I would do whatever the shop manual says.

 

I believe one of the Buick parts vendors has the washers. Probably Bob's.

 

Welcome to the forum!

Edited by Bloo (see edit history)

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On 5/18/2019 at 9:43 AM, Bloo said:

The exhaust manifold must be able to move with expansion. It gets much hotter than the head and it WILL get longer and the ends WILL move out. Anything that restricts that motion will cause the manifold to break. That is what you need to pay attention to.

 

The belleville washers just allow the manifold to move. They go on so the outer edge contacts the manifold and the inner edge contacts the nut. Soft washers could crush down and stop the motion.

 

Also pay attention to the studs and imagine the exhaust manifold getting longer. The manifold will probably hit the outside of the studs cold (to make sure the manifold won't hit the inside of the studs when it grows). If it is already hitting the inside of the studs and has no room to grow longer, you will need to do something about that.

 

Make sure the surface of the manifold is straight and flat. If it wasn't already warped, it probably warped when they welded it. Hopefully they milled it afterward, but if they didn't that could be why it leaks.

 

I don't know what sealer you refer to. You don't want to glue it down. I would do whatever the shop manual says.

 

I believe one of the Buick parts vendors has the washers. Probably Bob's.

 

Welcome to the forum!

I'm getting my engine ready to go back on chassis but am making sure I've torqued everything correctly after running engine.

I have good clearance around the studs except the last 2 at the firewall end being in close contact with the manifold(see photo). What are your thoughts on the clearance? 

I believe the washes I have are the originals? The are quitethick, flat with a small raised outer edge on the side that rest on the manifold and more rounded on the nut face. Belleville washes as I understood them have a slight curve in them. Was there ever a washer on the longer stud with the thick metal piece that clamps the end of the manifold? Not not thread left on the stud so I would imagine not

Looked on Bob's website but didnt see washers. Old Buick Parts had washes for the exhaust.

20190519_163200.thumb.jpg.47c67715bc58e71d8ce825c8f0efcaf8.jpg

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Posted (edited)

I can't really see well enough to tell, but it looks fine. The plate is the sliding memeber on that stud, so I don't think there would be any belleville washers there. Those belleville washers look like good ones. I suspect they might even be original.

 

Some studs can (and probably should) be in contact with the manifold, as long as they do not block motion as the manifold gets longer. For instance it looks like the manifold is touching the long stud. The manifold will grow further away when it gets hot. I think i see a gap next to that last stud (bottom of pic). That is also good. When the manifold grows it will get closer to that one.

Edited by Bloo (see edit history)

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On 5/20/2019 at 4:28 AM, Bloo said:

I can't really see well enough to tell, but it looks fine. The plate is the sliding memeber on that stud, so I don't think there would be any belleville washers there. Those belleville washers look like good ones. I suspect they might even be original.

 

Some studs can (and probably should) be in contact with the manifold, as long as they do not block motion as the manifold gets longer. For instance it looks like the manifold is touching the long stud. The manifold will grow further away when it gets hot. I think i see a gap next to that last stud (bottom of pic). That is also good. When the manifold grows it will get closer to that one.

From illustrations and original photographs I've seen I think they are the original washers. There is about a 3/64" gap next to the long stud and yes a much larger gap next to the last stud. 

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When I first looked at your picture I thought the bolts were bent and I wondered how that worked! Then I realised you have used a very wide angle lens. LoL.

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The best washers for this application are plentiful and inexpensive  and sold for Jeep Wranglers on Ebay. Use the thick copper faced gaskets coated with an oil and graphite slurry on both sides and torque to less then factory spec. I use 18 lbs to accomplish a good seal and have great vacuum with strong fast windshield wiper action which is always a good indicator of well sealed intake manifold. I also raise the hood on a warm day to release hot air after a drive as it gets amazingly hot. Just unlatching it and placing a small wood block under the edge works  quite well to release hot air. 

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I drive my 1937 Special with a 1952 263 straight eight a lot and had two manifolds crack. I knew nothing about special lube and washers so my cure was a complete shot in the dark but has worked fine for the last 20 years. Did away with gaskets and alignment rings and used red high temp RTV silicone. Haven't had an exhaust or intake leak for at least 20 years. I'm sure the manifold is free to "creep" between hot and cold cycles.

 

 

Pont. heater, Buick sealant 003.jpg

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