[001mustang]

My 351W SBF World Product Heads have square exhaust ports. My Hedman 88650 headers have oval ports that are too long and overextend the square head exhaust port flange area about 1/16". Since the header oval port is too big the header gaskets fail in short order (make a ticking sound). I am wondering if I can fabricate a header adapter gasket from 1/8" - 1/4" metal plate to properly mate the square head exhaust ports to the oval header ports?

[S10 Racer]

Originally Posted by 001mustang

My 351W SBF World Product Heads have square exhaust ports. My Hedman 88650 headers have oval ports that are too long and overextend the square head exhaust port flange area about 1/16". Since the header oval port is too big the header gaskets fail in short order (make a ticking sound). I am wondering if I can fabricate a header adapter gasket from 1/8" - 1/4" metal plate to properly mate the square head exhaust ports to the oval header ports?

Instead of fabricating an adapter plate, I would fabricate a flange and cut the header tubes off the old flange and weld them onto the new one. If you fabricate an adapter, you will have to use 2 gaskets instead of 1.

[SSedan64]

May find something here. > http://www.stahlheaders.com/flanges_main.htm

[4 Jaw Chuck]

A copper gasket will last in your application, save you some cash and install time as well.

[001mustang]

Fabricating and welding a new steel header flange sounds good but that could take all day or 2. The embossed copper header gaskets look great but how can I be sure the copper oval will fit the oval 88650 headers? If I fabricate a header flange gasket from 3/16" 6061-T6 Aluminum (Brinell hardness of 95 vs 38 for lead and around 120 for steel) will I need additional gaskets on both sides of the aluminum gasket?

[oldbogie]

Originally Posted by 001mustang

My 351W SBF World Product Heads have square exhaust ports. My Hedman 88650 headers have oval ports that are too long and overextend the square head exhaust port flange area about 1/16". Since the header oval port is too big the header gaskets fail in short order (make a ticking sound). I am wondering if I can fabricate a header adapter gasket from 1/8" - 1/4" metal plate to properly mate the square head exhaust ports to the oval header ports?

Yes, done all the time. You'll probably need 1/4, I don't even know why I said "probably" just use 1/4 or 3/8s. I'd use aluminum plate, it's a lot easier to work. Can be built with hand tools if you take a little time to watch your dimensions.

Somebody like KOOKs probably makes them for a Ford but they won't be cheap.

Bogie

[001mustang]

Thanks 2 all.
I plan to fabricate a DIY header flange gasket from 1/4" Aluminium bar stock.
I bronze welded a layer of bronze on the primary tube mating surfaces then flat board sanded the bronze down to 180 grit.
I wonder if I should use paper gaskets or no gaskets on both sides of the DIY 1/4" Aluminium gasket?

[h0trod389]

your gonna have more trouble with your current way of thinking than you might think..

header flanges are easy to make, sure it takes some time... but it will be better for you in the long run...

every time you get a gasket leak, do you wanna spend the money to buy 2 sets, or spend the time making gaskets?

skrew that.. IMO.

get a set of flanges from world to fit your heads, or make them..

3/16" steel will never warp on you. and no matter if your cutting aluminum or steel, its the same amount of work to make either a flange or a aluminum gasket...

as little parts as possible... thats what ive always been taught!

[oldbogie]

Originally Posted by 001mustang

Thanks 2 all.
I plan to fabricate a DIY header flange gasket from 1/4" Aluminium bar stock.
I bronze welded a layer of bronze on the primary tube mating surfaces then flat board sanded the bronze down to 180 grit.
I wonder if I should use paper gaskets or no gaskets on both sides of the DIY 1/4" Aluminium gasket?

My inclination would be that this will need to flange to transition shapes from the port to the header. Don't loose the sense that in 1/4 to 3/8s of an inch, this is still pretty abrupt.

It is acceptable to have header openings larger than the port's or at least not hanging any of it into the port, the converse is not acceptable. But a matched transition would be best. The flow of gases and to some extent liquids can be strange at transitions. When encountering a blunt obstruction the flow has to move out of the way and the resulting turbulance makes the area of the port act a lot smaller than it is. The transition to a larger area creates a thing call "vena-contracta" where the flow forms itself into a venturi that reduces the appartent area of the port. Neither is good, but the head on blunt is worse than the expansion. In practical terms , the expansion over the edge of a smaller port into a larger header tube offers a backward restriction to returning pressure pulses. This dampens their effect on reverse pumping of exhaust into the intake during overlap at low RPMs, but probably isn't worth the effort of figuring out except on a competitive racer.

I'd gasket both sides with an aluminum or copper gasket. Most aluminum plate you'll find for the adapter plate will be T6 hardness which is to hard to really bed parts into as a gasket. Gasket material, even Al or Cu is dead soft and thin so it will conform to surface irregularities, where the plate won't.

Bogie

[001mustang]

Plan A: adjust alignment of headers by lowering flange holes 1/16". Install oval copper gaskets if I can find one that fits 88650 hedman headers. Try to verify headers mate correctly before installing new gasket.

Plan B: Make 1/4" aluminum gasket and put soft gaskets on both sides.

Plan C: Fabricate better fitting flanges from 3/8" steel and mig weld then fillet weld with bronze. Not my favorite plan since I applied ceramic coating which I will have to completely remove (not easy) then reapply.

Thanks.