Got a 77 400 motor that runs strung and smooth but when I first start it it runs high oil pressure. When I drive it for about 20 min and come to a stop the pressure goes away! can anyone give me some advice on what could be the problem? Thanks in advance!

 

There probably is no "problem", as these motors are well known for having low oil pressure. What grade oil are you running, not that it makes much difference?

 

put a gauge on it and see what it is,rule of thumb is 10 psi for every 1,000 rpm,most likely engine is worn

 

hmm... i got about the same issue here. I installed a pressure gauge in mine. when i first start it it says about 60psi at idle, after about 15-20 mins of driving i stop at a red light and it will say about 10-15 psi. but while driving about 20-30 psi doing 35mph in 4th gear. is this normal? as far as i know the engine has never been rebuilt. run 10w40 in it.

 

that is normal, i have a internaional truck with a 345 and i only average 20-25 psi after i am wram and 50-60 PSI when cold, so that is normal

 

Cool, thank you