Due to the fourth port on my exhaust manifold sagging 3/16ths I'm replacing it with a new one. When I first took it off there was only one home made gland being used, and that was in the fourth port, The gasket being used was the "all in one" type. Certainly this was done due to the warpage years ago.
When I install the new one I'll use the traditional glands and copper rings. Properly tightened the manifold should stay true to form correct, especially if the spark advance is used as it should be throughout the operating/ driving range....Or, is the manifold doomed to warpage over extended use no matter what.
I think if you use the glands and rings, it shouldn't warp unless for some reason you really really overheat the engine. That might make it warp, don't know for sure. I like those copper rings that have the glands "built in", they cost a bit more but really work nice. Just sayin'
Keep it tight, and never remove it when hot.
Yes Charles, the gland rings should help. No, they're not doomed to warp no matter what.
In my experience they are doomed to warp no matter what. I even went to the point of custom making close tolerance chrome-moly gland rings and eventually the manifold still warped. Mind you, this was after thousands and thousands of miles.
How could there be any original ones left if that were true?
I suspect in most cases the warping was caused by those all-in-one things allowing the back end to sag.
Are the one-piece gaskets at $27.50 a set worth $20 more than the original style? I don't see how. Maybe that's why some of the major parts dealers don't even carry them.
Jerry, we know original cranks are doomed to break someday - and still there are thousands of good original cranks still in use all over the world.. It may take thousands and thousands of miles until a manifold warps as Tom says - and with careful monitoring and with proper glands it takes longer
Well, my oldest one is 95 years old and it ain't bent yet.
Jerry, I've never seen an original that wasn't straightened that was true enough for me.
This pile had one that was sorta straight.
Since getting too hot tends to warp them, and the one on my 23 was warped and had a leak, I ran at a fast idle with the timing retarded until the back of the manifold had a faint red glow. I had loosened up the rear clamp and got a bar under the manifold/exhaust pipe and gently applied upward pressure for a few minutes and it moved and I tightened it back up. No more obvious leak. I'd planned to remove it later this week anyway to either replace the glands or put on the dual exhaust one sitting on the garage floor for 2 years so I'll check how far from true it is.
Maybe it's a geographical phenomenon. East of the Mississippi, I've got 4 originals that I'm using right now.
I will admit however that I had a vaporizer style that I removed from my touring, (that seemingly fit just fine), but would not go back on due to warpage. Replaced it with another original.
Regardless of whether you use the 3 in one gasket or the rings, it is very important to use the glands. The glands will keep things in alignment. The problem is that all the heat from all the cylinder exhaust goes to the rear of the manifold which when hot makes the iron more pliable. The center glands will keep the center of the manifold from moving upward and the 4th gland will keep the rear from moving down. The weight of the exhaust pipe also helps to bend the rear of the manifold down. It might bend anyway, but less likely if you use glands. I have seen gaskets which have built in glands, but sometimes they only go through one side. If they are placed outward they are in the manifold. You need glands which go through both the ports in the block and the manifold.
Thanks everyone for some great responses to my question. At least now I feel confident that I can give my new manifold a fighting chance.
It's a shame that I had to change out the old one as it was an original script example, but due to being warped bad enough, the use of proper glands and rings were not an option. I would have been faced with using those huge ugly gaskets again.
Mark, thanks for the link. Unfortunately one of the things I don't have is a torch, so for now I won't be able to try that myself. I won't scrap the old one, but I will hang it on the garage wall as a memorial to a cast iron soldier that fought a good fight.