Hey All,
I finally un-moth balled my brothers 455 in his 70 Cutlass S this weekend. He bought the car cheap, with a mission to save it. The car is rough and was hit hard on the drivers side. We had no idea what condition the motor was in. After a couple hours of prepping, lubing cylinders and blowing out gummed up jets, we fired it up and the thing runs and sounds as smooth as a brand new motor. The only thing that bugged me was a little exaust leak. It sounded like it was under my feet while sitting in the car. Sure enough I isolated it at the manifold/flange connection, then I found a stripped out manifold/flange bolt. I just dug out a longer one, cleaned up the threads and put a nut on the top.. I loosened the other side and torqued them evenly and tight. Well, it helped a lot, but it didn't solve it.
Any advice??? There's no donut on these (right?), but is there a aftermarket gasket or something made to solve this problem?
thanks as usual...

 

No gasket. I would take it down, and look to see if the pipe is good, and if OK,retighten the bolts again,evenly.

 

Yep, I thoughtI probably should have taken it down and at least cleaned it off and inspected it better. Probably should get the torque specs and get out the little torque wrench to be sure they're even. Thanks

 

The flange on the down pipe has to seal to the 'ball-cup' side of the cast manifold. Believe it or not I've found that once it is evenly tightened if you tap around where the steel flange on the pipe meets the manifold with an air chisel with a blunt-ended 'bit' on the lowest setting it conforms the steel flange to the much harder cast iron manifold. A couple of taps working in a circle with the engine running and you can hear it seal right up. A muffler shop friend told me about it - Works like a champ!

 

Thanks! I'll give that shot. I love the little tricks....