Exhaust manifold

[Datsun 440]

I am just getting ready to install the exhaust manifold on a U20 from my 67.5 2000. Not sure if the early manifold without the flange will seal very well.Should I just use the 68 style with flange.
thanks
Arnold

[spl310]

Well, Nissan changed the design for a reason - sealing was likely a big part of that. If you have a good later manifold and front pipe, I would go that route.

[itsa68]

The later style flange (with donut) seals quite well and is easy to align and draw in the exhaust pipe on assembly.

Ray B.

[spl310]

What size donut did you use?

[itsa68]

Sid:
I have the late exhaust manifold with the 3 studs for fastening thru the exhaust tube flange plate which sits behind the donut bead of the exhaust pipe tube.
My exhaust tubing is 1.75" diameter, so I imagine the inside diameter of the donut would be the same unless the tubes beaded donut flange straight end was formed at 2" diameter when the flange bead was formed.
I looked under the car to try and find out, but couldnt see much because its bolted all together.

When had I installed the loose donut gasket to the tube, I recall that it had only a bit of play to the straight section diameter before the tube bead.

You might want to measure the diameter of your exhaust tube that goes into the manifold to determine the inside diameter of the donut you require.

Sorry I could not be of more help.
I'll have to check around to see if I have and old on kicking around to measure.

Ray B.

[Datsun 440]

Thanks for all your input. I do not think they use the donut seal. It looks like it is more of a compession fitting steel on steel ??

Arnold

[spyder]

I had a couple of manifolds crack so I tried a stainless flex adapter with a header. No cracking issues so far. I do not kow how easy it would be to adapt to a stock manifold setup.