401 exhaust manifold

[Geoff Dowdle]

Ralph ,
many years ago I had a large hexagon die nut made to clean/recut the threads before fitting a new brass exhaust rings (see attached photo)

I have found that the problem with most of these faulty exhaust manifolds is that rust builds up between the thread and the exhaust rings .
The die nut recuts/cleans the thread in most cases . It is important the renew the exhaust rings as the original are often damaged or oversize and lubricate the thread with high temperature grease before refitting.

A 400 owner in Australia had a manifold that the thread was completely removed . An engineer built up the thread area with weld and machined a new thread . This required a special gig to hold the manifold in the chuck of a large lathe .(see attached photo)

Geoff