Date: Wed, 29 Nov 1995 10:49:53 -0800 (PST)
From: Andrew Mace <amace@unix2.nysed.gov>
Subject: Re: Say what? dual Webers and Mk.2 "headers"
On Wed, 29 Nov 1995, Mark J Bradakis wrote:
>
> I know I am sort of slow sometimes, but WHY in the world would anyone want
> to take two perfectly good Weber throats and force them to feed only a
> single inlet port? Wouldn't you lose a lot of power and waste a lot of
> petrol by getting poor gas speed and lousy fuel atomization through the
> two throats?
Mark, I admit I wondered that myself. Seems to me that was exactly why
the factory developed the eight-port head for the 1147 for competition
purposes: alloy for rallying, cast iron for LeMans, etc. I'm no
engineer, but "2-into-1" doesn't make much sense to me for carburetion.
Of course, the eight-port heads are available again, from someone in
France, for an incredible price (which I believe also includes a
manifold for dual Webers).
Meanwhile, Pete Watson noted that:
> TRF have what appears to be functionally a replica of the MkII
> header in stainless steel, complete exhaust with dual mufflers, for the
> low, low price of only $600!
John Kipping Triumph Spares' catalogue list a Mk. 2 stainless steel
header for L125.00, and the rest of the system, also in stainless steel,
for another L80.00 -- FWIW.
> These headers were relatively rare even when they were new. I
> believe they were only supplied on the 1965 MkII, to homologate them
> for FIA Group 4 endurance racing (the famous Le Mans Spitfires). I was
> at an autocross in the mid-70's once when a Spitfire entrant had me
> help him convince the tech inspector that it was indeed a stock header!
Not quite. They pretty much could be found on all Mk.2 Spitfires. The
homologation theory doesn't wash, though, since the competition cars used
special eight-port heads (see above). Various tuning kits, including the
eight-port heads, were sold to the public, undoubtedly to satisfy
homologation requirements, but these were very different parts.
If the production car header was somewhat "rare" even new, it probably
was because they did tend to last at least a bit longer than did the rest
of the exhaust system, just as head pipes seem usually to outlast
mufflers and other pipes.
Andy "just one of those new repro eight-port heads would cost more than
my Herald did new" Mace
Andrew Mace
10/Herald/Vitesse (Sports 6) Consultant
Vintage Triumph Register
amace@unix2.nysed.gov
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