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Cosworth DFV tech


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#1 BritishV8

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Posted 04 January 2012 - 22:01

Please educate me about ignition systems used on Cosworth DFV Formula One engines. The literature I've read stops short after saying that DFVs used Lucas Opus systems triggered off 40-tooth tone wheels from the front of the crankshaft in conjunction with "conventional distributors" (mounted in the engine valley and driven off the back of the alternator) for spark distribution.

I've recently photographed a Tyrrell (circa 1972) and a McLaren (circa 1973) for upcoming feature articles They have two different ignition boxes mounted above their distributors. I'm curious to know why they're different.

On the Tyrrell, the box is labeled "Lucas Capacitor Discharge Ignition System":
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From the rear:
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On this particular McLaren, the box isn't labeled. It's similarly dimensioned, but has a hand-fabricated appearance.
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What appears to be an ignition coil is labeled Bosch, NOT Lucas!
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1) Was Opus used from the start of DFV production to the end? (i.e. roughly 12 years)
2) What's inside the distributor? (Surely no breaker points, right? Was it made specifically for DFV? By Lucas?)
3) What exactly is the function of a Lucas Capacitor Discharge Ignition System?
4) Is the Lucas Opus amplifier built into the Capacitor Discharge box?
5) Did all DFV engines use Capacitor Discharge systems? (I've not seen it mentioned in the literature.)
6) Does this unit provide a multi-spark feature, similar to what MSD capacitive discharge ignitions provide?
7) I know Cosworth used electronic rev limiters... is that function built into THIS device?

8) Do you think I'm correct that this particular Tyrrell is using a period original component whereas the McLaren isn't?
(Alternatively, did Tyrrell and McLaren use two different ignitions?)

Edited by BritishV8, 04 January 2012 - 22:05.


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#2 BritishV8

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Posted 05 January 2012 - 18:12

anyone?


FYI: today I've published my full set of McLaren M23 photos here:
Denny Hulme's 1973 McLaren M23 Formula One Racecar (M23/1)

ref:
Posted Image Posted Image

#3 Peter Morley

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Posted 06 January 2012 - 11:17

I can't give you a very complete answer, but you are on the right track.
The original ignition system was the Lucas Opus one which was closely related to the road car system that was just being introduced, the components were fitted inside a folded aluminium box.
The Lucas CD system is a later system which is much more reliable and uses a different sensor.
DFVs were used for such a long time that there were many changes made over the time - apart from internal changes, things like the water and oil pumps changed and different types were used depending on the particular installation and the mechanical fuel pump driven from the camshaft also came later as did electronic fuel injection in the later engines.

#4 Rudernst

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Posted 07 January 2012 - 23:31


Dont assume that a DFV that is fitted TODAY to a 1970ies or 1980ies F1 was fitted to that car in in period.
Cars and engines were frequently rebuilt and swapped around from older to newer cars or sold off from one team to another.
Some rentadrivers had their own engines and took them from team to team.

The engines themselves were suprisingly longlived and updated a lot.

Today You can find relatively young shortstroke DFVS in earlier cars that should not have them.
Nobody cares as the revs are limited anyway.

And as to the spark boxes:
They can die with no warning and it is wise to carry a spare.

Rudolf


#5 Lee Nicolle

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Posted 08 January 2012 - 05:03

I would have thought the worst place to mount those ign boxes would be in the centre og the intake, heat viabration would kill them.
One would hope they were better quality than 70s Lucas mainstream stuff, as theym struggled to run to about 5000rpm!!
Though 40 years down the track CDI boxes are still not super reliable. Of any brand!


































































#6 Doug Nye

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Posted 08 January 2012 - 17:21

I would have thought the worst place to mount those ign boxes would be in the centre og the intake, heat viabration would kill them.
One would hope they were better quality than 70s Lucas mainstream stuff, as theym struggled to run to about 5000rpm!!
Though 40 years down the track CDI boxes are still not super reliable. Of any brand!


Lucas OPUS ignition became renowned in period as Lucas 'Opeless...which it could often prove to be. In fact it was pretty much the best system around at the time of its introduction, and when it worked well it was good. When it didn't work well it was an absolute swine to get right.

DCN


#7 cheapracer

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Posted 08 January 2012 - 17:58

I've recently photographed a Tyrrell (circa 1972) and a McLaren (circa 1973) for upcoming feature articles They have two different ignition boxes mounted above their distributors. I'm curious to know why they're different.


Look again at the box and the plugs, it's the same, just upside down on the Mclaren I believe.


#8 RTH

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Posted 16 January 2012 - 13:13

Lucas OPUS ignition became renowned in period as Lucas 'Opeless...which it could often prove to be. In fact it was pretty much the best system around at the time of its introduction, and when it worked well it was good. When it didn't work well it was an absolute swine to get right.

DCN



It is a little known fact that there is a way of preventing the common cold

.............You simply give it a Lucas part number......then no one could get it.

#9 Tony Matthews

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Posted 18 January 2012 - 22:50

Look again at the box and the plugs, it's the same, just upside down on the Mclaren I believe.

It does look as though the McLaren box is upside-down, but if it was, surely the coil and push-in connectors would be reversed. They aren't...