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May 18, 2016 10:30 am
May 18, 2016 10:30 am
Subject: V12 4 carburetter: SU D4s v D5s
My V12 was originally a 4 carb car, as evidenced by the float chamber posts, but converted to 2 carb when sold in 1946 due to petrol rationing etc. I've always assumed it had 4 D5s because of the float chambers, and that perhaps just the Le Mans V12s had D4s...but subsequently I've discovered that original private customer 4 carb cars were fitted with D4s.
So in my innocence I bought a pair of D5s, and when Mel rebuilt the engine, he rebuilt my D5s and fitted those. The manifolds, if it helps, are Alan Brown supplied, and I'm sure the throat diameter matched the D5s. Mel's main (reprehensible!) business was converting ruinous V12s into Le Mans (4 carb) racers, so I would have thought he would have stated the D5s were unsuitable. On the other hand, he never started the engine, neither have I, 6 years later. Mel is retired now so no contact.
Does anyone have experience of 4 carb set-ups using D5s? What needles and jets are used?
Would I be better sourcing D4s? What is the casting number on the D4 body (I recall on the D5s it's D1949), and will the D4s have the same flange stud spacings?
Laurence
My V12 was originally a 4 carb car, as evidenced by the float chamber posts, but converted to 2 carb when sold in 1946 due to petrol rationing etc. I've always assumed it had 4 D5s because of the float chambers, and that perhaps just the Le Mans V12s had D4s...but subsequently I've discovered that original private customer 4 carb cars were fitted with D4s.
So in my innocence I bought a pair of D5s, and when Mel rebuilt the engine, he rebuilt my D5s and fitted those. The manifolds, if it helps, are Alan Brown supplied, and I'm sure the throat diameter matched the D5s. Mel's main (reprehensible!) business was converting ruinous V12s into Le Mans (4 carb) racers, so I would have thought he would have stated the D5s were unsuitable. On the other hand, he never started the engine, neither have I, 6 years later. Mel is retired now so no contact.
Does anyone have experience of 4 carb set-ups using D5s? What needles and jets are used?
Would I be better sourcing D4s? What is the casting number on the D4 body (I recall on the D5s it's D1949), and will the D4s have the same flange stud spacings?
Laurence