B3 to B6 exhaust headers

[reddragon]

Hello, I'm currently preparing to swap a B3 16v SOHC engine for a B6 16V DOHC, and if possible,
use a set of Maxim Works exhaust headers I have for the B3, on the B6.

The ports match on both engines, but the stud pattern is different. Only the 4 corner studs line up with the header flange.

both.jpgmw.jpgb6.jpg

To make them fit, a new flange would need to be welded to the header pipes, or 5 new studs tapped into the B6 head.
While I would have to pay someone to modify the headers, I could easily tap the new studs myself. I'm hoping that
someone may be able to answer a couple of questions I have, to help me decide which option to choose.

Is there any reason why tapping new manifold studs might be a bad idea?
How deep could you drill into the B6 head around the exhaust ports, before weakening or interfering with internal components?

[TominMO]

What about getting a B6 exhaust manifold gasket and laying it on the B3 header, to see the differences? Mark the places on the header where there are holes on the B6 gasket but not the header, then drill out new holes to fit it to the B6. You might have to have some extra material welded on if the new holes would be too close to the edge of the metal; or in some cases maybe you could just use a large washer in a location where it wasn't too far off.

I think this would be much better than messing with the head itself.

[reddragon]

Good point, looking at it that way might be the way to go.

The 2 bottom holes could be drilled into flange, the centre stud lines up with the cutout on flange, so a washer can be used without drilling. The 2 top studs could use washers, just need a bit of packing above the studs so the washers sit flat against the flange.

gasketb6.jpg

[Festiver]

I know this is off topic and I apologize for that but 16v b3 that's awesome

Sent from my XT1585 using Tapatalk

[reddragon]

Yeah they came out in the '96 - '02 Mazda 121 Metro (aka DW Demio) with F series gearbox.