Just fitted s/h radiator to TP auto wagon after getting it REAL hot yesterday (hot enough to vaporise fuel so injectors didn't get any)
Motor seems to be running ok no bubbles in water to indicate blown head gasket.
While checking everything i took the oil filler cap off and at idle there was a fair amount of air pulsing from the rocker cover,the engine is not blowing smoke
Is this normal or have i fried the rings ?

nope that blowback is normal

I would have a look at the thermostat next

did you flush out the 2nd hand rad before fitting ?

check that your thermo switch and fan are working
open the heater control while filling the radiator back up

Thanks for the advice, the overheating was caused by a burst co0re tube 25mm long 70mm from the bottom. As it turned out the side rail had broken it's solder allowing flex.
Earlier yesterday while north bound on Springvale rd i had an extremely near miss with a loaded semi that did a right turn across 3 lanes of peak traffic, i expect the violent avoidance move was enough flex to kill the coroded tube, damn that bull bar looks big 50mm from drivers door.
I put 30 yrs of motorsport lessons learned to good use and proved the TP handles well in a crisis.
LOL took me 2 hrs for the stabbing pain of my heartbeat in my lower back to subside, pleased to have myself and the car back in action.
Damien.