Have tried one set of gaskets with steel ring and copper o ring, still have leak in #one port, there are other gaskets in Snyders are they any better, this is for my 25tt thanks Dan
Have you checked the manifold to be sure it's straight? If its warped you'll probably never get it sealed up completely.
Check the manifold ports, if pitted file or mill smooth and flat. Usually takes 30 to 45 minutes to do by hand. Also check block surface for pits. These can be filled with Thermosteel, available at auto parts stores,its good up to 2400 degrees. Dont use the green gaskets.
Try those individual copper doo-dads that are basically the ring & O-ring all in one. They cost a bit more, but man do they work, even on a warped manifold, provided it's not too warped.
Dan is onto something with the comment on pitting. I used Permatex high temp Ultra Copper RTV for that, and the stock steel rings and copper gaskets. So far so good. I don't care for the one-piece gaskets either. I assume the one-piece copper rings also will work, but I'd rather pay $5 to $7 a set for stock than $30 for those.
The nice part about the one piece copper rings is that you can use them again and again - just wire brush them clean. Mine have already paid for themselves since I've removed and replaced the manifolds multiple times.
Dan Wheeler - if you are not fussy, Snyder's has a great sale going on manifolds in their Scratch-n-Dent section. The manifolds are perfectly serviceable, they just have some finishing flaws - grind marks, etc. Might be worth picking one up and saving yourself some headaches.
Thanks for all the good info will fill the poor cast on the #1exhaust port and try the heavy copper rings, Dan
Here is a picture of what we did to one car which had a very severely pitted exhaust port. We bored it out till it was smooth and round and then turned an insert. The insert was snug and pushed into the block. The manifold held it in place.