Are you using the old water pump off your previous old engine...v belt style...
or are you using a water pump that came on the 86 engine?
86 on engines use serpentine belts, that require a reverse rotation water pump...
Using a reverse rotation pump on a v belt drive engine will have the water pump cavitating and reducing flow as engine speed increases....
Just buy yourself a new standard rotation pump...just make sure the drive flange length is correct...there are short and long pumps...
