Clean (wire wheel...), degrease, use sealant of choice.
I've always used firegum and never had a problem, as long as you don't go mental on the amount you put on - just whatever you do, don't put it together and then start it and rag it up the road, it'll still be wet and it'll just blow out the sides. Leave a few hours and then start and idle for 5 mins and it'll warm up enough, stop and leave for another few hours and it'll be fine.
The way I see it is that the flange isn't moving, once that paste is in there and it's set, it's not gonna get pushed out or anything. I've had some SERIOUSLY warped adapters that I've not even bothered flattening and sealed them fine with firegum. Long as it's set and you don't rag it up the road in the first 30 seconds, it'll be fine. Make sure your fasteners are good and you actually torque them up correctly.
I've always used firegum and never had a problem, as long as you don't go mental on the amount you put on - just whatever you do, don't put it together and then start it and rag it up the road, it'll still be wet and it'll just blow out the sides. Leave a few hours and then start and idle for 5 mins and it'll warm up enough, stop and leave for another few hours and it'll be fine.
The way I see it is that the flange isn't moving, once that paste is in there and it's set, it's not gonna get pushed out or anything. I've had some SERIOUSLY warped adapters that I've not even bothered flattening and sealed them fine with firegum. Long as it's set and you don't rag it up the road in the first 30 seconds, it'll be fine. Make sure your fasteners are good and you actually torque them up correctly.
