i just replaced a cracked exhaust manifold on my 69 valiant. it seems to be leaking from the head. do i need to have the 2 manifold milled so they line up perfectly? i loosened the 3 bolts that hold the manifolds together and tightened them on the head and it didn`t help. would i be better off getting a set of manifolds from the junkyard, cleaning them up and putting them on?

You can get better manifold gaskets from Remflex or the Australians. You could have the manifolds planed or use a big file to DIY, or your junkyard idea might work. The Australian gasket solved my long-term header leak on my 340c.i.d. car.

Yes, they are meant to be perfectly flat. You may be able to get away with them a little crooked, and a thick gasket may help, but it puts stress on almost every connection and stretches your manifold runners which can cause a break.


You can slot the holes a little if it doesn’t need much.


It might work. It might be worse. If you have a good manifold that isn’t warped and the heat riser works, I’d fix it and make it work.

Danny

Flat manifold surfaces are definitely important, and it is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions. Also, all the attaching hardware needs to be correct; see article (which has not been updated with the info on the good gaskets).

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