Hi-po exhaust manifolds

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340sFastback said:
Do you still need pictures? Cause my '69 340 has the manifolds bolted to it with reproduction hardware. But its under a table with blankets and plastic piled on it but I can get pictures if they still needed.
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Don't go to too much trouble. The issue that I am having a problem with is the placement of those washers. My service manual says they only are to be installed on the studs on the #2 and #8 exhaust ports. There's actually a photo with arrows pointing to those studs. But it makes no mention of the driver's side manifold.
 
I believe this is correct. Some of the available hardware kits come with more cup washers than you need, but information varies about using them on the middle four bolts.

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According to my service manual, which only shows the passenger side manifold, you have it laid out properly. I appreciate the photo, since the driver's side manifold isn't covered. I have not only done an Internet search, but I have also checked every repair manual I have. Don't understand why that is left out of all the repair manuals.
 
Actually, I need to correct myself. The manual shows the passenger side with conical washers on the the 2 sleeve nuts. I don't see how that is possible. Obviously the photo supplied by 6T9QDA is correct and the manual incorrect.
 
yeah, you can leave the conical washers off the center port bolts, but at $500-800 for a pair of these, I sure wouldn't risk busting the ears off of my manifolds in the name of what is supposed to be "correct".
 
str12-340 said:
yeah, you can leave the conical washers off the center port bolts, but at $500-800 for a pair of these, I sure wouldn't risk busting the ears off of my manifolds in the name of what is supposed to be "correct".
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Good point. There's no way to get cone washers under the sleeve nuts, but it might not be a bad idea to put them under the four center bolts.
 
As above, there you go! Use them under all the bolt heads and nuts that they fit under. The sleeve nuts themselves provide a wider bearing surface on the manifold than bolt heads or regular nuts. I have never used the sleeve nuts in the form of studs and then sleeve nuts. When I got my bolt kits the extra studs were already loctited in the sleeve nuts so that they looked like long fat bolts with threads sticking out of the bottom. It's already a chore to get the manifolds on with the far end studs in place without adding even more to maneuver around.
 
When I received my bolt kit (many years ago) from Layson's, I certainly don't remember the sleeve nuts being assembled with the studs attached. But, that was a long time ago.
 
70Duster340 said:
According to my service manual, the conical washers are placed on the studs on the #2 and #8 exhaust ports, but none on the #4 and #6 ports. Unfortunately, it only speaks of the passenger side. It only mentions the torque specs for the driver's side. No mention of the conical washers for the driver's side. Would it be safe to say that those washers would be on the #1 and #7 cylinder ports?
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I have a set of those manifolds too n I’ve used the conical washer but I never knew why they are used. Does anyone know their purpose ?
 
CFD244 said:
Just measure the depths of the holes and buy 5/16 course bolts of the appropriate length. Don't forget the cone washers. Save where we can!
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5/16"? I thought they are 3/8" like the Fords and Chevys. The new design engines went to 8mm which is only a couple of thousandths different to 5/16". The 3/8" rarely broke the bolts like the new ones.
 
4spdragtop said:
Is there a benefit to using brass nuts? I thought they were sometimes used oem?
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Brass nuts will not rust to the stud like steel nuts will. If using the steel nuts I use an antiseize so they can be removed later. The manifold to headpipe nuts are important to do this to. Otherwise you likely need to heat the nut to cherry red and break it loose. Not generally required with antiseize.
 
str12-340 said:
yeah, you can leave the conical washers off the center port bolts, but at $500-800 for a pair of these, I sure wouldn't risk busting the ears off of my manifolds in the name of what is supposed to be "correct".
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Heat expansion in the length of the manifold. Expansion is X thousandths per inch, so on say 3" the expansion will be very little over #s 3 and 5, and 4 and 6, while #s 1, 7, 2 and 8 will be considerably more length change. I believe the conical washers let the manifold move a bit under them so it does not break the manifold.
 
str12-340 said:
yeah, you can leave the conical washers off the center port bolts, but at $500-800 for a pair of these, I sure wouldn't risk busting the ears off of my manifolds in the name of what is supposed to be "correct".
Click to expand...
Heat expansion in the length of the manifold. Expansion is X thousandths per inch, so on say 3" the expansion will be very little over #s 3 and 5, and 4 and 6, while #s 1, 7, 2 and 8 will be considerably more length change. I believe the conical washers let the manifold move a bit under them so it does not break the manifold.
The new designs the manifolds expand and contract and the bolts flex to allow that. This is why the 8mm bolts break, generally flush with the head.
 
70Duster340 said:
But will antiseize hold up to the heat from the exhaust?
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Yes. Used it all the time on the turbo mounting studs for transport truck engines and construction equipement. Those at night are visibly cherry red for hours at a time under load. The antiseize has the grease carrier cooked out while the active antiseize component coats the threads and stays in place. Kind of like a galvanized or titanium coated bolt.
Smokey Yunick stated every bolt or nut should be installed with an antiseize or loctite on the threads. Heat can be used to release loctited bolts or nuts so does not function on exhaust.
 
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