My mechanic wants to machine my manifolds FLAT so that they can be installed with no gaskets. I've never heard of doing this, have any of you done it, with success? He says this is the best way of assuring no problems down the road.
I wouldn't machine them unless they were warped bad enough to actually cause a leak. Even then, if they are warped real bad you would only want to machine off enough to get them to seal. The more material you remove the more likely they are to warp because they keep getting thinner and thinner. But you didn't mention what manifolds on what engine?? The old original manifolds tend to bend on the small ear areas because they're too thin from the factory. If you cut them down the ears will bend even easier. I really got tired of trying to get mine (stock factory manifolds, 318) to seal and finally went to the 360 magnum (super thick manifold) on the passenger side and the 340 driver's manifold (a little more heavy duty than 273/318). Haven't had a hint of a leak for years.... but like I said, you didn't mention what your working on??
