Hi Shaun, when I trial fitted my current manifold (I changed to EFI) I found that the gap was too small for the cork. The cork prevented the inlet manifolds from sealing on the main manifold gaskets. In my case the gap was only a couple of mm so I then used RTV instead. My original manifold didn't have that problem, but I can see that in the 'v' of the heads, a small dimensional change in the cyl head spacing can make a large difference in the gap left where the cork gaskets go. If you trial fit without the cork, and the gap is less than say 75% of the cork thickness, then you might find issues in compressing the cork enough to seal the manifold gaskets, so I would go for RTV or find some thinner cork. If the gap is 75% to 90% of the cork thickness, you could use the cork, but I would always go in with feeler gauges to satisfy myself that it's all going together properly as the manifold is tightened down. You may need to use RTV anyway to seal the ends of the cork.
