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MG MGB GT V8 Factory Originals Technical - idling speed

I've just finished a three day 750 mile tour of Devon in my V8 - its first serious outing. Just one word - AWESOME! Porlock Hill pitch black in the rain anyone? (Won't mean a thing to our US friends). Not a hitch with the car - ran beautifully.

One thing though. Idling speed seemed to drop towards the end of the trip to about 400 - 500 when hot. The car has just had a service so everything should be in tune (?).

Can anyone tell me:

1) What the correct cold and hot idling speed range should be, and

2) How can I adjust the idling speed to what it should be?

Thanks as ever.

Richard Saunders

I would love to do Porlock Hill in my BV8. I have pictures of my dad's Cortina rounding that really tight steep corner. I remember my dad convincing my uncle to take the picture while on our holidays back in 1967! I've been searching South West Ontario for a road like that for years....but nothing comes close. I bet it really tested your brakes on the way down.
Martyn

Richard,
I take it you mean the old toll road, not the modern replacement. If you want to try it uphill in daylight with no fear of anyone coming the other way, then come and play in the MGCC speed championship. It's the Sunday after Silverstone weekend this year if anyone wants to watch although it's not a great spectator venue (too long and spread out).
David Smith

The factory V8 idle speed should be 800 rpm. As this can drop to 500/600 when hot and the fans are on with a resultant drop in oil pressure, I run mine at about 950 to compensate.

You don't say what carb(s) you have - the twin SUs each have a vertical spring-loaded idle screw between the carbs. There are also two other 'screws' which are really bolts with low-profile heads secured with a nut and only really accessible when the accellerator is opened to max, these are the fast idle screws for the choke control. If you have twin carbs be very careful to adjust both screws by the same amount and in the same direction otherwise you will cock-up the settings and it takes a couple of hours of careful work to set them up again.

There are a couple of hills in Heartbeat territory on the Yorkshire moors that are tighter and steeper than I remember Porlock although my wife wouldn't let me make a diversion to try out the 1:3 near Pickering. The best hill I have done though is the Hardknott Pass in the Lake District - really two hills in one because as soon as you have got up it the other side immediately goes down again. Awesome views from the top while your car pivots on the peak, though.

PaulH.
Paul Hunt

Thanks Paul for the advice. It works a treat; the car is now running at about 800 and generally seems smoother and more responsive (?). Will running at a higher idle speed cause the engine to run hotter (or get hot enough for the fans to have to cut in sooner)?

As for the other hills - thanks but no thanks; I'm still puckered up from Porlock!

Richard
Richard Saunders

Richard - yes, but it will only be marginal, and it will keep the oil pressure up in summer.

Cheers,
PaulH.
Paul Hunt

This thread was discussed between 06/03/2000 and 08/03/2000

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