mr3dman

7.4mpi rebuild threw in a mag roller cam and springs. stock exh through Y pipe. no exhaust bellows to drive. I have pulled the exh and had the surfaces checked flat/ pressure tested no leaks. Leak down check done, no problems.
Now the problem, is this mod prone to water reversion? I am getting some water at idle, but not enough to affect how the engine runs. Any ideas? idle is currently at 750rpm

getrdunn

iTrader: (7)

What are the cam specs? For the time being bump your idle a little. Did you notice any diff in the performance with the cam change.

mr3dman

the motor is in a cruiser, was looking for some more at 3k and got it. The boat gets on plane way better and picked up 300rpm on top to boot. I am way happy with the torque increase. Working with Mark at Precision for the ecu and he has been great. I just have this water issue.

the cam
MERCRUISER # 431-850478
.004 300*/ 300*
.006 288*/288*
.050” 224*/224*
.200” 125*/125*
Lift .483”/. 483”
ICL 109*
LSA 115.5*

Griff

The stock magnum cam should not revert any water. Its possible that the cam may not have been degreed in properly.

mr3dman

I did double check that last year. I am starting to wonder if maybe I was sent the wrong cam by the guy that sold it to me.