I found this on a different website but it might be helpful to discuss here
a warped header flange is a rather common flaw and yes milling the surface will effectively help get the outer flange surface flat and square so the gasket is much more likely too seal.
its rather obvious that the headers have a silver ceramic coating and your header gasket would most likely leak as most gaskets don,t match the header primary tube edge exactly.
brazing or silver soldering the gap, is unlikely to work for two reasons,
first brazing generally used a silver and copper or copper brass mix and most brazing rods melt at about 800F -850F so a good high speed high rpm run would cause exhaust temps hot enough and for long enough to cause a brazed joint to weaken over repeated runs and eventually fail,
plus the area would need to be heated over a fairly wide area for brazing to stick well, that probably would destroy or damage the ceramic coating and appearance.
a skilled TIG welder could probably seal the joint in a local area , from the engine side of the header flange without damaging the ceramic finish,on the outer surface very noticeably,
and allow you to use a file to smooth the gasket surface so that's the route ID GO!
yes the ceramic coating will potentially be damaged but TIG welding results in a far smaller area being heated and ceramic coating by design are heat resistant and,
the rest of the header tube and flange will tend to act as a heat sink
(ESPECIALLY IF THE AREAS NOT BEING WELDED ARE WRAPPED IN OLD WET BATH TOWELS)
while the TIG WELDING IS BEING DONE
https://www.corvettecentral.com/c4-...twood-nd-101684?returnurl=/c4-84-96/?count=45
remember
WITH TIG WELDING YOU CONTROL BOTH THE APPLICATION AREA,AND AMOUNT OF HEAT INDEPENDENTLY AND AREA AND AMOUNT OF FILLER ROD USED INDEPENDENTLY, IF you ONLY WELD A SMALL 1/4" SECTION AT A TIME AND LET THAT COOL BEFORE PROCEEDING,YOU WON'T WARP THE HEADER TUBE OR FLANGE, (ESPECIALLY IF THE AREAS NOT BEING WELDED ARE WRAPPED IN OLD WET BATH TOWELS)
with MIG welding you can't get heat without adding mig wire
(faster easier but far less versatile)
http://garage.grumpysperformance.com/index.php?threads/most-versital-shop-welder.1594/
a warped header flange is a rather common flaw and yes milling the surface will effectively help get the outer flange surface flat and square so the gasket is much more likely too seal.
its rather obvious that the headers have a silver ceramic coating and your header gasket would most likely leak as most gaskets don,t match the header primary tube edge exactly.
brazing or silver soldering the gap, is unlikely to work for two reasons,
first brazing generally used a silver and copper or copper brass mix and most brazing rods melt at about 800F -850F so a good high speed high rpm run would cause exhaust temps hot enough and for long enough to cause a brazed joint to weaken over repeated runs and eventually fail,
plus the area would need to be heated over a fairly wide area for brazing to stick well, that probably would destroy or damage the ceramic coating and appearance.
a skilled TIG welder could probably seal the joint in a local area , from the engine side of the header flange without damaging the ceramic finish,on the outer surface very noticeably,
and allow you to use a file to smooth the gasket surface so that's the route ID GO!
yes the ceramic coating will potentially be damaged but TIG welding results in a far smaller area being heated and ceramic coating by design are heat resistant and,
the rest of the header tube and flange will tend to act as a heat sink
(ESPECIALLY IF THE AREAS NOT BEING WELDED ARE WRAPPED IN OLD WET BATH TOWELS)
while the TIG WELDING IS BEING DONE
https://www.corvettecentral.com/c4-...twood-nd-101684?returnurl=/c4-84-96/?count=45
remember
WITH TIG WELDING YOU CONTROL BOTH THE APPLICATION AREA,AND AMOUNT OF HEAT INDEPENDENTLY AND AREA AND AMOUNT OF FILLER ROD USED INDEPENDENTLY, IF you ONLY WELD A SMALL 1/4" SECTION AT A TIME AND LET THAT COOL BEFORE PROCEEDING,YOU WON'T WARP THE HEADER TUBE OR FLANGE, (ESPECIALLY IF THE AREAS NOT BEING WELDED ARE WRAPPED IN OLD WET BATH TOWELS)
with MIG welding you can't get heat without adding mig wire
(faster easier but far less versatile)
http://garage.grumpysperformance.com/index.php?threads/most-versital-shop-welder.1594/
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