dicknellen wrote:
I had a mid 90s E-350 w/460 v8 MH, had exhaust header & front brake problems.
The first exhaust manifolds that I took to a machine shop to be re-surfaced after warping were from a Dodge. Shop tech said "Van, huh?" and I said Yes. Told me the air flow around van (therefore Class C) Doghouses is so limited that they warp more manifolds than other vehicles.
Fast forward to our E350 with a 460 in it. Warped manifolds. Again, I had them re-surfaced. By the way, most cylinder head machines can't do exhaust manifolds. I had to find a shop with a "belt sander." I reassembled with stamped steel gaskets (not the fiber ones), NeverSeez on both sides, and just enough torque to crush the stampings. Left the sheet metal "heat stoves" off and used new bolts. I also replaced the exhaust with a 3" FlowMaster system, which I think carried more heat out the exhaust than OEM did. Never warped again.
I believe we abuse our manifolds if we take a flying dive off the interstate into the nearest fuel island and shut the key off. That is a lot of rapid cooling of manifolds that were as hot as they can get. I think a slow exit, slow approach and a few minutes idling helps with this.