A number of suppliers in the UK at least (try Google), but you need to be
very careful in what you actually buy.
I've come across four types in my time and used three of them. Originally
they were single, thick, metal-faced sandwich gaskets, which have quite a
good ability to cope with the flanges not being flush with or parallel to
the head by a small amount. They do put the manifold closer to the inner
wing than the others though. The next were thinner, green and black
composition and were useless. Not only didn't they compress much, but with
the very small overlaps between flange and head blew a piece out on the
first decent run. The third type come in pairs i.e. one gasket covers two
exhaust ports and whilst they are a metal sandwich again they are quite thin
(Clive Wheatley http://mgv8.homestead.com/gtex.html). The fourth type I've
seen but not tried and they have a ripple-effect on the sealing faces which
is said to give an improved seal, but I think they may only be thin shim
i.e. very thin. These are in the MGOC mag but I can't find them on their
web site.
The problem with the V8 manifold is two-fold - first is that most of the
tubular types seem to have a mis-match in the alignment of the ports which
significantly reduces the amount of overlap in some areas, and causes port
obstruction in others. The second is that they warp in use, which results
in the four ports being offset by various amounts, the inner pair touching
the head but the outer pair not, as well as all the flanges being at an
angle to the head instead of parallel. As well as resulting in a very poor
seal and high failure rate of the gaskets you can't even get the bolts
through the flanges into the head without overdrilling and filing them out.
Added to that the holes in the gaskets are quite a bit bigger than the
manifold pipes and particularly the head ports, which reduces overlap even
more.
I've had my manifolds on and off because of blown gaskets more times than I
care to remember, the drivers side of which needs the rack to be removed,
but so far the way I have it now has lasted the longest. I welded struts
between the flanges to hold them apart and stop them turning inwards, which
keeps the bolt holes aligned as well as the faces parallel. I tried to find
an engineering company that could skim the flanges so that all four would
touch the head but no-one could come up with a way of holding the pipes
securely enough. I settled for spending some time on a belt-sander, which
improved things, but the outer two were still not quite touching. That I
resolved by delaminating an old gasket and using a shim from that on each of
the outer flanges to even things up. Full story at
http://www.mgb-stuff.org.uk/wn_engineframe.htm and click on 'V8 Exhaust
manifolds'.
I think some manifolds now come with the flanges in pairs (RV8 style?) which
would help, but ideally you need all the flanges in a single strip of steel.
I did see some blanks like this at Clive Wheatley and he said it wasn't
until he had those cut to the same dimensions as the original assemblies,
and offered one up to a head, that he realised just how poor the port
alignment was. I'm not sure if he got more recut to the correct alignment
and made up with pipes or not.
PaulH.
----- Original Message -----
> Can anyone tell me the brand and part number for my Rover 3.5L V8 exhaust
> manifold gaskets. Looked in archives but could find nothing.
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