OK. So the heads went back on and seemed to run OK (still getting a little warm in traffic). Got back to inspect things and noticed that the valley gasket has lifted up considerably. It is still bolted down and has not come off at the back...but has been pushed up to the point where it has split and there is oil leaking out of it. Been throwing various theories around and the more reasonable one is that the carb has back fired and due to the lack of there being flame traps, has pressurised the top end. How come it didn't do that before? Well perhaps because the head was blowing and that was it easiest path out...now that it's sealed up it cannot do that.
The other consideration is that I am using early rocker covers which do not breathe as well as the later ones...yet I do not have the breather on the block as I have the later 4.6 block. So it probably was not the reason why I had excess pressure, but it will do it good anyway. The plan is to copy the SD1 setup which has the cannister flame trap on one side splitting off and going to both carbs and rocker cover an "open" vent.
Want to get it sorted so I can drive it, rather than trailer it, to the Classic Restoration Show at the NEC
These are the rocker covers I bought...I don't think they are as visually appealing as the older style ones...but function over form.
I also took a decision on the cooling system. I am going to drill/clean in some way or another the water outlet on the carb tower as that is almost fully blocked (I get a trickle and that's about it). Have a coolant tank that is t'd off from the radiator outlet and also feeds the carb tower outlet. I also think I need a much better fan - I think the ebay cheapo jobbie is pretty lame - a trip to my parents house will hopefully be fruitful for that
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To get to the NEC I will also need a much bigger fuel tank - it's about 7 litres and that doesn't get me very far at all - perhaps 10 miles! (it will of course be much better once the engine has been tuned - again - another thing that needs doing before the NEC). Fingers crossed.