I dropped my engine in with the headers & hung my exhaust. I bought the metal gaskets & installed them but I can still see where the pipe from the headers collectors & the exhaust pipes side are not sealing together. The flanges are starting to bow from me trying to tighten them so much. What can i do to get these things to match up & seal properly?

 

Best thing is to bolt the collectors to the headers before you bend and hang pipes. Making sure they seal up then hang exhaust then weld.

So if the collectors and exhaust are not welded you can remove the exhaust from the collectors then make sure they seal up then replace the pipe back into the collector then weld. If the exhaust is already complete try rotating the exhaust to line collector and header flanges.

If they won't seal up then the flange might be bent. Which you would have to remove the collector then use a hammer to straighten the flange.

 

When you say "metal gaskets" are they flat and about 1/16" thick. My header were not sealing well anymore either. I separated them to clean them up and regasket. Mine had a solid thick metal "doughnut" gasket. They are supposed to have a softer metal on the outside of the solid core but mine had all burned/wore/rotted away. My collectors are 2 1/2". and I found replacement doughnut gaskets at Fairfax Autoparts, a Napa brand dealer, for $1.52 each. Put the new ones in and tightened them up - no leaks. Here are a couple shots of the old ones, the new ones were about 1/4" wider with the softer lead like gasket.









If you get one of the dumb guys who have to look it up good luck. The first guy I spoke to was very confused. I said I have Cutlass with aftermarket exhaust. I need a 2 1/2" solid gasket to go between the header collector and exhast pipe Then I showed him the old part. "WOW a 2 1/2 collector - I must be on a V6 Accord or Passat!" What!?! The next parts store knew what I wanted.

Adam

 

Thanks guys. I'm going to take the exhaust down & try to straighten it out a little. I also picked up a couple of those doughnut gaskets that im going to put in there when i hang it back up.

 

I've had very good luck with the copper gaskets on both the head and collectors, but they won't span large gaps!
"78 Vette L-82, had replaced the 'cardboard crap' 3 times over a year, [daily driver] one set of copper, and haven't seen him in 3 years!