I just had a Vortech supercharger installed on my 502EFI motor (1999 27'Fountain) and upgraded the drive gears (Teague). I have run the boat 3 times since and the 3rd time I really opened her up (80 mph (not GPS)5100 rpm) and I had oil blow out the dipstick. Is it as simple as a tighter dipstick or is more venting necessary to prevent seals from blowing out or even the crankcase exploding. Your advice is greatly appreciated.

How many hours are on the engines? Sounds like a lot of blowby.

There is only 43 hours on the motor.

I am not knowledgable when it comes to superchargers. But, for whatever reason oil blows out of the dipstick, I would run a leak down check on this motor to check what the ring seal is like.

Check ring seal. Where do your valve covers vent to? I have mine going to the inlet of the procharger. How do you like the supercharged power? Greg

This is pretty standard in the factory big blocks in the marine industry. The dipstick goes to the bottom of the pan, and when the rings don't seal, the pressure vacates the pan and the easiest path is pushing the dipstick out. Simple soloution is changing your oil to a different weight, put a throttle return spring on the dipstick, or tap the dipstick and put a threaded style dipstick. If you want to confirm this, doa compression check. Usually the only other thing is overfilling the amount of oil by either putting too much in, gas in the oil, or water in the oil.

Thanks,
Dustin

I am thrilled with the results of adding supercharger. It comes out of the hole much quicker, the mid range is awesome and I can run 80 mph vs 68 mph. I had the gears upgraded and had it switched to run a 26 right handed Bravo I prop. I feel it handles better now with the right handed prop and have protected against blowing out the top of the drive. I tried to do everything right and be proactive so I don't have problems out on the water. Well my first and hopefully last problem is this oil blowing out the dipstick.
Regarding the rings: my installer did a compression check before installing the unit and it must have been fine or you would think he would have said something.
I appreciate the feedback.

MRP, did you ever figure this out????

What a difference a year makes. The motor has been torn down and bored out to a 509. The reason I had the blowby was sloppy piston fit and rust damage on the cylinder walls due to the previous owner not winterizing properly. Motor runs awesome now. It dynoed at 650hp at 5400 rpm. Boat runs 85+ on a stock 26 pitch prop.

Not uncommon.
If you start looking at other supercharged engines you will see a spring retaining the dip stick. If I remember correctly, even the supercharged Mercruiser HP motors have a spring on the dip stick.
Don't worry about it!
Dennis Moore