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The Achilles heel of the V6 has always been the inlet manifold, causing the breathing
and mixture distribution between the cylinders to be very inefficient. |
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Tests proved in the seventies that compared to the centre, the front & rear
cylinders were some 15%-20% down in flow rate, and very lean in mixture calibration
with the centre cylinders rich when set by the exhaust gases. All sorts of experiments
took place in motor sport to counteract this due to the “Group 1” regs at the time
requiring the car to use the No of carbs it was designed with. |
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A number of mods took place with plates inside the manifold deflecting the mixture
and all sorts of carbs were tried, with the best results coming from a single 42/44
DCNF downdraft carburettor, anything larger is pointless as the V6 simply cannot
breath any more, but the engine was always down on its midrange torque capabilities,
the one big plus this engine has in spades!! |
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For road use again all types of carbs have been tried including Holley four barrels,
and twin carbs with the centre mounting blanked, but nothing works as well as the
“Ford rallye sport” triple downdraft 42 DCNF carburettors and manifold, and nothing
looks as good!! A throttle body per cyl is still best, be it carb or injection,
but if you want to keep the car “period” it’s carbs (although Ford did experiment
with injection in the early 70’s in 4x4 rally Capri’s), unless you’ve got a GAA
under the bonnet!! |
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Spend as much as you like on the engine, you might end up with nearly as much top
end horsepower, but nothing brings the V6 to life like the triple’s do!, the gains
are 80% midrange, 20% top end. As you will recall this engine in road trim is all
about mid range torque, even in high states of tune power is tailing off after 5500
rpm. The engine can be made to rev over 6000rpm but torque has long gone, it's struggling
to spin the massive internals and simply can’t breath anymore, therefore this high
torque goes hand in hand with high gearing to keep the revs
where they do their
best work. The standard engine with the triples fitted will give around 165 bhp
plus this huge gain in the mid range with instant throttle response. |
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The complete kit has long been discontinued but they do become available second
hand, Ebay, motorsport publications and possibly Capri clubs are possible avenues
to obtain one but they are now rare, expect to pay around a £1,000. You do occasionally
see complete engines for sale with triple Weber’s fitted. Burtons performance centre
in Ilford London I believe, still sell the manifold at around £500. As for carbs,
36 /40 /42 DCNF Weber will all fit, with 40 DCNF still available new at £271.00
each (all plus vat). |
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Once you have obtained the impossible, fitted them on the engine, stood there for
hours dribbling and drooling with your tongue on the floor, it’s finally time to
close the bonnet. |
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UUUURGHH!!! It doesn’t fit any more AAAAAAARRRRGHHH!!!! I’M NOT TAKING THEM OFF!!
NO, NO NO, no, no, no, as you're dragged away kicking and screaming!! |
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While having breakfast the next day depressed, you stare at the washing up bowl
wondering if you could glass it in the bonnet to cover the triples!!, This is how
desperate you become!! I was condemned to fit a bump on the bulge. |
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Having acquired another bonnet, a friend and myself raised and widened the original
power bulge, it was then fitted to the car and while it was a classy piece of work
I was not inspired and the bonnet never got painted and was eventually sold. |
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I had decided the triples have got to fit under the standard bonnet somehow, and
the only way I could accurately see, was to cut a hole in the bonnet, so I did!!
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It was obvious the trumpets would have to go, so they were removed, this left the auxiliary venturis proud about ¼” from the bonnet so now time to think. |
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The engine had been set up with various tests carried out on a dyno, one proved
a loss of 7 bhp without the trumpets, so not too much to worry about, plus I have
got to run filters, there was a foot of “stand off” above the carbs on full power
( fuel vapour) and I didn’t want the car to go up in flames!!, also the use of a
filter king pressure regulator was mandatory with the “Facet red top” electric fuel
pump filling a bucket in 10 seconds. |
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While on an exploratory trip to Euro spares in Halstead Essex (Italian car breakers)
to obtain some Lambo / Maserati spares (Arm & legs being the currency!!) I spotted
a Maserati V6 on the floor with triple DCNF’s!! but more important was the three
skinny heat spacers between carbs and manifold which I managed to purchase. After
paying, I waved goodbye with my remaining arm and hopped back to the car!! |
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While on an exploratory trip to Euro spares in Halstead Essex (Italian car breakers)
to obtain some Lambo / Maserati spares (Arm & legs being the currency!!) I spotted
a Maserati V6 on the floor with triple DCNF’s!! but more important was the three
skinny heat spacers between carbs and manifold which I managed to purchase. After
paying, I waved goodbye with my remaining arm and hopped back to the car!! |
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Recalling my trip to Euro spares I remembered the Ferrari carbs were fitted with
much shorter venturi’s. On studying the part I could see no reason why they would
not work shorter so I cut ½” off them all, and re- tapered the ends with drills
held in the hand and finished with emery cloth this produced good results. I could
shorten them further if needed, and if it didn’t work the venturis were still available
new. (£7.00 each) |
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I managed to obtain some s/hand “Speedo graph” oblong chrome filters which were
suitable for cutting down, unfortunately not available new anymore but could be
made from aluminium, as the original Marcos filter, quite easily. The filter clamping
nut stays were ground away from underneath and a local engineering firm machined
some new at 37 m/m long. With a small extension of 3 m/m through the filter base
plates allowing them to be peened over with a ball pein hammer; this worked really well, in fact exactly how they were made at “speedograph”. At the other end they
were drilled and tapped to accept pan head set screws to bolt the filters together,
this gained another 4 m/m and once fitted they looked professional, although they
would be slightly restrictive. |
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With the bonnet closed we now had an acceptable clearance, “SUCCESS”!! Time to repair
the hole in the bonnet then!!. |
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The carbs do need a manual choke cable fitted, (easily found at auto jumbles) and
once set up is only needed for a few seconds. |
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Phil Ward |