Thanks... I have both of his books, but unfortunately they are
about 4K miles away.
I remembered that the post-SD1 heads had bigger valves, but
never understood what the TR8 is considered... from a US
perspective, it's pre SD1, but from a European perspective,
it's post... since that's where they were made, I would assume
that the TR8 got the bigger valve heads.
Also, the posts I've seen referring to big-valve heads were
referring to engines newer than both of the Hardcastle books...
either the 4.2 or the 4.4 (maybe the 4.0 - which is just a
3.9 with cross-bolted mains from what I understand - same bore
and stroke).
Thanks,
Kevin
On 13-Jul-2000 Ian Crocker wrote:
> The Hardcastle books have info on valve sizes. The pre-sd1 had 38mm inlets
> and 33.3mm exhausts. The SD1 had 40mm inlets and 34mm exhausts. You can fit
> 41.4mm and 35.5mm valves on the standard SD1 seats. These are commonly
> called big valve. With bigger seats you can use 43mm/37mm and this is the
> size used on many TVRs.
>
> The SD1 inlet ports measure 25mm x 39mm at the outer end. The RV8 heads
> are 25mm x 40mm. My standard SD1 heads are ported to 26mm x 43mm.
>
> SD1 exhausts are 20.5mm x 31.5mm. RV8 uses 24mm x 34mm. My ported SD1 heads
> are 28mm x 38mm.
>
> Regards,
>
> Ian
> --
> Ian Crocker ian@btcase.bt.co.uk www.seight.com
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