Pre-cat exhaust port sizes

[Barreti]

Have any other pre-cat owners noticed this about their cylinder head exhaust ports?




Its not surprising I've been having problems with blowing gaskets.
SPEND - this is what I was trying to explain on the phone (and thanks very much for your help mate)

My JP performance SS manifolds are already the same shape as the ports, but a little narrow so I'll be tweaking them.

[griffter]

I'm not sure I understand what the picture is telling me. Is it that the port is bigger than the gasket? This is because TVR worked the ports. Ideally you want open out the gasket to match the ports. Ideally ideally you want to match the manifold and ports of course. Is current advice still to use bimetallic gaskets (which of course are much harder to open up but I thought were much more reliable)?

[Barreti]

Sorry Griffter, when you've worked with something for a while it all looks self-explanatory when in fact I can see how you might not have a clue what the hell I was getting at.

The white side is a template for a gasket taken directly from my exhaust port and this is overlaid on a standard Rover V8 gasket I had in the drawer.

I'm having stainless reinforced Micatherm gaskets made from that template by Ian P Greenwood who advertises on here. The advice from Tim at ACT who sells the bi-metallic and waffled gaskets is they can't be altered other than trying to tap them into shape - they certainly can't be cut to shape.

Although the manifolds are a similar shape they too will be tweaked to match while I wait for the gaskets. I'll post before/after pictures of the manifolds against a template later.
So I'll be in your ideal ideal position when I bolt it all back together

What I was wondering is if anyone else has noticed they have arched ports like my template, rather than square ports like the gasket.

Edited by Barreti on Friday 20th April 10:13