Non Std Exhaust Gaskets....?

Paul Thompson 'Hooligan' · 08-24-07, 08:11 PM

Hi all -

I'm working on a 302 at the moment that has had steel adapter plates fitted to the heads for the fitment of headers on a wider bolt pattern than standard.

One problem it creates though is that std 302 exhaust gaskets will no longer fit between the plates and the headers, as the bolt holes are all wrong, plus, the heads have been ported and standard gaskets are marginal at best..

SO - does anyone know of a reliable source of suitable gasket material so that I can cut my own bespoke items? - preferably in UK but not essential.

I am also considering cutting them from copper plate. I did this many moons ago for a highly tuned pinto engine that we could not get a reliable seal on. They sealed well and each time the manifold was removed, we just cleaned then heated the gaskets with a smokey torch to soften them, then back on they went.

Question is, has anyone else tried this? - any pitfalls you can think of? and if I do do it again, what thickness plate would you recommend? I was thinking of about 2mm but can get it in:
1.36 / 1.55 / 1.67 / 2.07 / 2.26

Comments.

Paul Thompson 'Hooligan' · 08-24-07, 08:43 PM

typo - oops

DaveWharran · 08-24-07, 08:59 PM

Paul,
I've had good success using Grafoil sheet for exhaust system gaskets. It is a graphite material sandwiching a thin stainless core. It can be cut with scissors, punched with hole punches, etc. Grafoil is a bit fragile as far as the graphite material, but not overly so if care is used. I'd say generally that once installed then disassembled, you'd probably want to cut a new gasket rather than trying to get the old one to reseal. The graphite will usually stick to the flange surfaces and delaminate from the stainless core during disassembly.
It withstands high temperatures and will seal rough surfaces on the flange, head, turbo, etc.
Two websites from a quick Google search:

Brands

GRAFOIL® and FLEXIBLE GRAPHITE PRODUCTS

Dave

Paul Thompson 'Hooligan' · 08-24-07, 09:03 PM

Thanks Dave - looks very similar to the stuff I've found below

laminated graphite jointing 2.0mm thick :: Vintage Car Parts

Also available in 1, 2 or 3 mm thickness.

The fact that you have previously used it to good effect makes it sound very promising.

Rick · 08-25-07, 02:40 AM

Many of the newer aftermarket heads now utilize a wider bolt pattern for the header flanges to allow for larger tubes. You may want to compare dimensions with some of those (World Products, comes to mind as well as some of the specialized Edelbrock stuff). Maybe you will be able to find some already available insted of fabricating your own.

Paul Thompson 'Hooligan' · 08-25-07, 03:34 AM

Thanks Rick - I'll check that out too as it would certainly be an easier option..

Colin Artus · 08-25-07, 09:29 AM

You dont need to use a gasket - a 5mm bead of clear silicone works really well. Allow a skin to form before assembly and it will last until the next dissasembly. It's not necessasry to use the high temp stuff on a normally aspirated engine.