Crankcase Pressure
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Crankcase Pressure
Running 7psi Procharger setup on a couple 500HP motors. Both motors fresh but mostly stock. I seem to have alot of blow by coming out the crankcase breathers. The valve covers have the baffles in them but oil is almost spraying out. I plan on making my oil fill caps breather caps. Is blow by common with this set up or do I need to pull the motors apart and inspect the rings? I did the break-in procedure I have always done with new rebuilds. The motors have about 10 hours on them now.
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Chesepeake Bay poker run this weekend Philm, you in?
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See you next weekend.
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Not sure about the ring gaps... I had a well known local speed shop do the short blocks and they knew they were marine blower motors.
It is hard to say if they did it from the beginning. I did the break-in with out the chargers and used conventional oil. There was no blow by then. After I connected the chargers, is when I noticed the oil in the bilge and started looking for its source. I'd say it has gotten worse as I have run it.
I did a compression test this afternoon and every cylinder was at 200psi. I will do a leak down this weekend.
It is hard to say if they did it from the beginning. I did the break-in with out the chargers and used conventional oil. There was no blow by then. After I connected the chargers, is when I noticed the oil in the bilge and started looking for its source. I'd say it has gotten worse as I have run it.
I did a compression test this afternoon and every cylinder was at 200psi. I will do a leak down this weekend.
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200 psi? What kinda compression ratio was motor built around? Most blower motors are around 8-1 to 8.5-1 and cranking compression with a run of the mill cam is around 150 or so, just curious. I built a 502 years ago with a procharger and was never happy with the blow by, I have used zero gap rings in last few motors and they have had very little blow by/leak down, fwiw, Smitty
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You could be rattling the pistons from mild detonation which can cause a lot of blow by as the rings lose control. Might want to check your tune up, and like Smitty said 200psi cranking is way high, I'd confirm with another comp gauge.