On Sep 7, 1:13pm, CWNicholls@aol.com wrote:
> Subject: Re: Spit Exh.Problems...
> In a message dated 95-09-07 07:04:41 EDT, RICHARD.JACKSON@nene.ac.uk (Richard
> Jackson - Network Technician ext. 2570) writes:
>
> >---------------------------------------------------------------------
> >
> >Something that sprang to mind here, When the U.S got the 1500 engine they
> still
> >had single down pipe(like the MK IV), right (? please correct me, or flame
> me if you wish)
> >so therefore what I am thinking is did they (you) still get the
> >chassis cut out as we did to accomodate the extra size of the twin downpipe
> >even though they (you) didn't get it, if not, then the chassis will require
> a
> >bit of chopping about (Did any parts of the US get the twin SU's for that
> >matter)
> >
> >Rich.
> >----------------------------
> Glad you mentioned this...
> I haven't installed the manifold yet, probably won't for some time (I have a
> header there now).
> So the word is that this manifold is NOT from a Spitfire, but from a
> Dolomite??
>
> Or are you saying that it (the 2 outlet mainfold) was on some Spitfires, but
> there is a chunk cut out of the frame to let it fit?
>
> You're right, the Mk 4 (IV) Spitfire, 1971-72, has a single downpipe as did
> the 1500's (73-74) without the catalytic converter. In 75 the converter was
> added along with a chunk missing in the frame for clearance, still a single
> pipe.
>
> If I hear you right, the manifold into 2 pipes I'm describing will require a
> modification of my frame (since it's a '74) for clearance. I'm not excited
> about that.
>
> As far as the 2 carbs go, the Mk3 ('67-69) had dual SU 1.25" carbs. I think
> the Mk3 '70 had a single Stromberg as did all cars afterwards. The fellow
> selling the 1.5" carb setup and exhaust manifold maintains the non-US
> Spitfires had the 2-1.5" SU's and 2 outlet exhaust manifold setup, although I
> can't find any evidence in any books I have as yet
>
> Please further enlighten me on this manifold setup!
>
> My 1300 engine in my '74 ex1500 Spitfire (with GT-6 pistons, balanced,
> ported, cam, milled head, heavy valve springs, headers, 2-1.25" SU's). was
> out of my original '68 Mk3. I almost scrapped it after finding a cylinder
> heavily scored by a wristpin without the circlips installed (PO), but found
> that a .040" overbore would remove the damage!
>
> Thanks...
> Clark
>-- End of excerpt from CWNicholls@aol.com
Clark,
I installed the UK based dual su 1.5s on my Spit earlier this year. I
also installed the QuikTrip headers at the same time. I used a basically
stock exhaust pipe going into a GT6 muffler. The sound is quite nice.
I have been playing with the tune on the carbs all summer, and I think
that I have finally got it right. (I'll know for sure this weekend).
I have noticed a great improvement in acceleration, in fact the first
to second upshift is almost neck snapping.
I don't know what my fuel economy is going to be, I don't really pay
attention to it any more! The engine is stock 1300 ('73 1500 model),
and it is tied to a stock OD equipped trans.
The only problem that I have had on the installation is the choke. I
have yet to figure out how to hook up the choke cable so that it works
properly. I will probably sit down this winter and over-engineer some
kind of mechanism.
Doug Mitchell
Twenty year owner of the same car, I am my own DPO.
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