Outer Limits 4x4 Board

my motor is an old p76 4.4 stroked out to 4.7ish and after getting her back in after the rebuild on start up she makes a "howling" sound for 10-15seconds

It's defintly vacuum related take the oil cap out and it stops! (and you nearly lose your hand down into the head)
Different oil cap didnt stop the sound, removing rocker cover breathers doesnt stop the sound, new rocker cover gaskets didnt stop it. ohh and its only while the motor is cold

what could be making the noise and how could i stop it?

Simon

Hi i had the same thing happen when i changed my carby on my p76 engine and i fix it by moving the rocker cover breather on the drivers side to above the carby.
Also check your one way valve breather mine sits on the pass side.
hope this helps

Yeah sounds like you have your crankcase breather connected to manifold vacuum- it should connect in between the carby and the air filter somewhere i.e. above the butterfly not below it.