1GGZE Header flange

[Axel]

OK so I'm taking the factory header to the laser cutter tomorrow.
I'm have the holes cut slightly larger to 1 1/2" (38mm) as I've found a local supplier of mandrel bends in that size.
I've just noticed something odd with the bolt/stud holes though.
There are 9 holes in total but only 2 are close to the size of the original studs while the othe 7 are slightly larger (you might notice on the above pics)

I can't seem to see any reason for it, surely this would increase the chance of movement.

Should I have all the stud holes cut the same smaller size or have the cut the same as the factory item?

[the_random_hero]

Seems to be a common Toyota thing (same on my 4A and fairly sure same on the 5E), pretty sure it's used for locating the manifold correctly. I'd cut it to the size of the original holes so you don't have any problems locating the manifold relative to the port holes.

[Axel]

Yeah I decided to trust in Mr Toyoda and went with factory specs on the bolt holes.

[Axel]

Picked up the flanges from the laser cutter this morning.

Cost $100 for the 2 in 12mm mild steel.
Very happy with the result.

[mullett]

Hah! Damn, should have kept an eye on this thread, I'll need more soon. Does he still have the drawing on file? Might get a couple for myself, except with 35 mm ports...

-RM