374
Cooling the V8 engine in the MGB
Bill McCullough with a V8 Roadster (Green Mallard 4313) and an MGBGTV8 Conversion (Vermilion 3123) has made a painstaking research into the cooling system used on the Factory MGBGTV8s. His aims were straightforward - he wanted to know how the system worked and why overheating can arise. In essence Bill has found the heater matrix or radiator is connected in parallel with the main radiator (when the heater valve is open) so you would expect a greater cooling effect with the heater "on" being the sum of the two heat losses. But in fact the mode of connection results in a reduced flow through the main radiator which is by far the bigger heat dissipater with result that the net cooling effect is reduced. Based on his findings he has modified the MGV8 cooling system and achieved remarkable results. By carrying out his research and modifications on his two V8s he has tried to avoid the possible distorting effect that might result from experimenting on one car might have, so believes his results are robust. This article will certainly make you think and is likely to generate a healthy debate within the V8 fraternity. (Jan 08)
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Fig 10: Completed conversion - top heater hose bleeder vent behind the air filter box.

As this article runs to eleven pages with photos and diagrams, it can be donwloaded and viewed as a PDF document. It will be included in Volume 11 of the V8 Workshop Notes series on CD. V8NOTE374
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Feedback on Bill McCullough's article

Response from Tony Lake - this has been published as V8NOTE375 (31.1.08) More

Feedback from Allan Doyle on his experiences with cooling modifications. (1.2.08)
I had some work done on my car a few years ago and afterwards noticed the water temperature gauge doing a little dance over to the right after a cold start, then settling down to normal. One of the „improvements“ to the car had been to replace the bonnet sealing strips around the engine bay. The original 30 year old rubbers had probably been allowing some hot air to escape upwards.
Do you know if the "exhaust manifold through the inner wings solution“ has any effect? I’ve not heard of RV8s having our problem.

Comments from Gordon Hesketh Jones in response to a query from Allan Doyle. (1.2.08)
I did fit RV8 manifolds to my car as per Note 248 and it does make a huge difference as the hot air at last has an escape route! Certainly the heat can build up in hot Summer traffic jams, but beyond that, no problem and of course once on the move again, the temp does come down far more quickly. RV8 manifolds are available now from many sources – mine came from MGB Hive and required a fair amount of “gasket goo” to achieve a good seal. I am told that Clive Wheatley’s are better in this respect.


Response from Gordon Hesketh-Jones
(1.2.08)
I did fit RV8 manifolds to my car as per Note 248 and it does make a huge difference as the hot air at last has an escape route! Certainly the heat can build up in hot Summer traffic jams, but beyond that, no problem and
feedback continued . . .

of course once on the move again, the temp does come down far more quickly. RV8 manifolds are available now from many sources – mine came from MGB Hive and required a fair amount of “gasket goo” to achieve a good seal. I am told that Clive Wheatley’s are better in this respect.

Comment from Victor Smith (1.2.08)
And one should add the reinforcing rings are available for the holes - I think they come from BMH at Witney.


Reply from Gordon Hesketh-Jones (2.2.08)
If you think back almost five years to the fascinating presentation during the 25th Anniversary week on the history and the evolution of the RV8 by John Yea and David Bishop, it was quite specifically stated that torsional tests on bodyshells with the holes cut in the inner wings for the new manifolds, both with and without the reinforcing rings, had been carried out and there was no difference between the two sets of figures. Having said that, I had already fitted these rings to my own car, and frankly I have seen some absolutely god-awful installations where holes had been blithely cut, and the rings NOT fitted.
What is important when changing to RV8 manifolds is to make sure that the supplier also provides either a detailed drawing, or a (cardboard) template for the cutting of the holes. Again, I have seen some mess-ups where rings were fitted but this info was not properly supplied.

Comments from Tony Lake (2.2.08)
They are set out in a V8NOTE "More on V8 engine cooling" as V8NOTE375