Reading Chris and Jerry's account of their speedster trip and the problems with their exhaust manifold makes me wonder a solution I've thought of but have never tried. It likely wouldn't work but here goes. As I've gotten the manifold glowing from lack of advance or too lean a mixture, could you intentionally do that and place a small jack under the exhaust or manifold and slowly tweak it up, since that is the apparent cause of it warping in the first place?
You got to think about how hard that heat is for the block and valves. 50 something years ago I would sometimes retard the spark and light a cigarette. I wouldn’t do that today.
I've used the first method twice. It's amazing the weight of the wrench does it.
Sorry but why would you want to subject the engine to that much heat and stress if you don't have to? When rebending the exhaust manifold, generally you used a lot more heat anyway and it does not work all the time, many are cracked/broken in the process.
Second Larry, It works... Just take your time and don't spot heat it.
I've never had very good luck using methods such as those above for a manifold that was more than just a little bent. The problem I find is that the holes, although in alignment, are no longer spaced correctly. As such, the manifold still will not fit onto the block if you use close tolerance rings. I built a straightening jig that uses a series of wedges to force the manifold into the exact correct attitude in regard to both straightness and spacing. It works a treat. Only problem is it takes about half a bottle of acetylene to straighten a badly bent manifold.
Use the rings. Cast iron grows when heated. The growth is a function of temperature and time. You can keep the exhaust manifold straight just by remembering to use the rings.
I think a torch is a better way to heat the manifold rather than running the engine too hot. And I would do it off the car in a fixture or on a scrap block. As Mark says, you need a bit more temperature anyway.
Old cast iron wood stoves are warped all to hell by the action of too hot a fire for too long a time. Some are warped so bad that cracks open up in the fire box pieces. For some reason steel doesn't seem to have this flaw. Formula 1 steel headers are run yellow hot and as far as I know don't warp.
Are formula 1 steel exhaust manifolds available for the T? Who has them for sale?
No formula 1 for Ts to my knowledge. Formula 1 manifolds cost hundreds of dollars. Not worth it and T owners not like to pay about $1000 for a manifold.
If you straighten your manifold with the torch and wrench method, DON'T push down on the wrench or your time is wasted.Otherwise I think the method would have worked for me.