Maniflo or Janspeed, but the latter will be very expensive I would imagine. They did used to make a replacment for the H120 manifold whose design isn't that great & you can get some extra BHP by having a nice manifold made up. A pattern using the old one is perfectly acceptable of course & is fine unless you want more power. G
A friend of mine (Martin Maltas) makes tubular manifolds for Commers for either iron or alloy head engines. I'm pretty sure he's done one for a Holbay engine but if not I'm sure he could make one given the right port pattern. He's based in North Yorkshire, if interested PM me for his details. Here's an example of what he does for the Commer
Exhaust manifold
Posted - 10 Mar 2019 : 19:39:32
G
