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MG MGB GT V8 Factory Originals Technical - V8 fuel consumption?

I recently bought a 75 chrome bumpered V8. Can anyone tell me what the correct idling speed is, what the oil pressure range shouild be at crusing speeds (50 - 70 mph overdrive top, and what fuel consumption I should expect?

Thanks
Richard Saunders

tickover = 800 to 850
oil pressure 45 to 65 cold, 35 to 55 hot according to my memory and estimation, found 1 book that says '42' but doesn't state revs or temp.
fuel consumption = inversely proportional to right foot. I have seen 28 mpg touring in France
and expect around 22 to 24 pottering around in UK.
HTH
david.smith@stones.com

I agree with David's figures but would add Roger Parker's statement on hot idle oil pressure for Police V8s - "What oil pressure?". Mine is about 12 to 15 on a hot day after a blast down a motorway. Workshop Manual supplement says 42 normal, 34 idling (no temps, presumably hot), but this would be for a 'new' engine, not a 100,000 miler.

It also takes a while for the full pressure to register on the gauge when starting from cold. Don't worry about this, just see how long it takes the gauge to drop back to zero when cold and you will realise it is as much a case of high resistance in the gauge piping as slow build up in the engine. The gauge take-off point was moved from the filter to the pump at some point for this very reason.

The oil system in the V8 is described as a "high flow, not high pressure", presumably because of double the number of oiling points.

PaulH.
Paul Hunt

Another bit of trivia, when MG built the V-8, they changed the oil pressure relief spring to a stiffer one, since initial tests with the Rover spring showed the pressure dropping to near ZERO on the gauge at idle! Rover used idiot lights instead of gauges, so no one got alarmed at this low pressure until MG went to a gauge. The uprated spring supposedly gives ~25 psi at idle.

The range of oil pressure produced by the Rover V-8 also explains why MG went to a 0-60 psi gauge instead of the regular 0-100 psi used on the 4 cylinder cars. People were alarmed when the gauge showed less than half the needle travel at high speed cruise, thinking that something must not be "right". I heard that some later V-8s may have had 0-80psi gauges, and some may have gotten out of the factory with the 4-cylinder 0-100psi gauge.

Cheers,
PK
Paul Kile

'Zero' whas what I meant by 'What oil pressure?'. Clausager says that the gauge was originally 80psi, then changed to 100psi in June 74, subsequently changed to 60psi but no indication when. Maybe they ran out of 80s before the 60s arrived.

PaulH.
Paul Hunt

The fuel gauge on my chrome bumpered 75 V8 goes up to 80????
Richard Saunders rsaunders@symantec.com

er... that should be oil pressure gauge!
Richard Saunders rsaunders@symamntec.com

This thread was discussed between 29/09/1999 and 05/10/1999

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