I have a crack in my current manifold (not enough to leak though) and I have one that has no cracks I will replace it with. The heat riser valve was shot (very loose, the spring dosn't work and the stops where gone). I removed it, and replaced it with a 4.5 inch bolt that runs through it. Is this an O.K. fix? Will it effect the sealing any when the manifold gets hot? Or should I put two bolts in each side so the manifold can expand and contract properly? I had the heat riser welded open on my old 400 manifold because of a bad leak, and had no problems with warm up (it was a cold blooded engine anyway). A friend said to put some type of epoxy to help seal it up, any recomendations? I'm asking this after the fact, but can reverse if necessary.

I don't think epoxy will hold up under the consistent heat of an exhaust manifold..

The long bolt with some washers on it will probably hold up for a while, but id be willing to bet it would start leaking eventually. If it were mine i would just tap the holes and thread two short bolts in.

Another option that may prevent the through bolt from leaking in the long run: If you can find a large-enough piece of asbestos gasket (for manifold to pipe or header collector to pipe connections) cut out two small rings the size of the washers you are using and tighten it up.

-Aaron

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The "Silver Bullet"
87 Ram D150

I remember when I had the original 1 barrel & intake manifold on there I could never get the choke cup to seal right and no gasket material ever held up, so I wanderd on over to the chrysler dealer to see if by any longshot chance they had any original gaskets... they didn't have any but gave me a printout of all the other dealers that did in the US. I called them up and got all of them. Some thought I was a bit wierd calling cross nation for an ity bity gasket

On my exhaust manifold, I removed the valve and tapped the holes to use regular bolts to seal it up. I also brazed up all the cracks. This is still holding after 45 days of steady driving (50 miles or so per day). The car is also extremely cold blooded. With the hood up, the carb ices up. With it down, everything is fine after warm up.

I tried to tap the holes, I only ended up with a bruse on my hand from pushing on the handle! Maybe its because I have a cheap tap set... What size tap did you use? I run the heated air air cleaner in the winter, so warm up should be easier than an open cleaner I run in the summer months.

Use a 7 / 16 - 20 unf tap, this thread accepts a couple of flex plate to crank bolts, which I screw in from the inside. (The head forms a good gas seal and it's a cleaner look)
I use my arch welder to tack the outer end of the bolt so it will never rattle loose.
I also find that a no heat valve Slant takes a long tome to warm-up.
DD