need master gear head help on pressure coming from valve cover.

[nova]

at above 2000 rpm I start getting pressure or oil smoke coming from one of my engines valve cover breather/oil fill cap. The engine does not smoke from the exhaust and water is clear from the thru hull exhaust. I notice my PCV valve chatters at idle and is attached to the carb base. eng spec is twin 302's, 9to 1 comp, new crane cam hyd lifters, new dbl timing chain and gears set straight up. MSD ign box, MSD mag dist. , Speed Demon 650 vac secondaries, timing is 16deg @ idle and 36deg wot. Here is the kicker boys! At WOT when I start to back off throttle I get a whistle sound like a like vacuume relief (what the hell is that?) only this motor. My question is. Could this pressure in the valve cover be a bad valve seals or guides. Or do I fear a broke or stuck piston ring..(how do you tell or check)..(heaven forbid)....Please help, My wife is going to kick my ass if I don't stop doing things to my boat.

[Nucking futs]

The whistling is the carb, and is normal. How many hours are on the engine? have you done a comp. test or a leak down on it?

[nova]

motor has about 100 hrs on it, only got used once last year. I was thinking sitting all last year may have been bad. Have not done compresion test. Never done a leak down before.

[celeb1]

Do you notice any RPM differences between the two motors? Does one spin faster than the other? Back your timing off a few degrees (both motors) and see if that clears up your issue. What thermostat are you running, could be that you are running too cool and the rings are not sealing completely. Worst case is bad rings but you can rule that out with a compression test. Bad valves seals and you would see it out your exhaust and smell it.

[nova]

both run very cool 120-130 degF, total timing 36. have not done a compression test. Guess I'll need to ck. Never done a leak down and what would that show and how do you do?

[Kevin Heine]

Nova,
A leak down check will tell you alot. First thing is do a compression check to see wich cylinder is off. I believe 5-10 pounds is normal. So if you have one cylinder that is over 10# off thats the cylinder you'd check. Oh yeah, I'm sure you know but you want to do a compression check with the motors warm.
Once you find the low cylinder, remove the valve cover and completly loosen up both of the valves. Then screw in a airhose into the spark plug hole of that cylinder. The air hose I'm talking about is designed just for this. It will have the proper threads and will also have an oring to seal against the head. The other end of the hose will have a quick connect to accept the hose from your air-compressor. Set your regulator at 0 slowly increase the pressure up to about 60 psi then listen for the any air leak. If its coming through the valve covers, (pcv valve or oil fill hole) its rings. If its coming through the carb its intake valve and if its coming out the exhaust its exhaust valve.

[cruser]

If it's coming from adjacent cylinders or the water thermostat it's a head gasket.

[BUSBY]

Has anyone thought of too much crankcase pressure?
Ask some of your buddy's if the have a leak down tester ... it'll hook onto your hose line and screw into your spark plug hole.
Sometimes the regulator on your compressor isn't accurate ... but you should only have 5% leakage ... (the tester calibrates off of 100 psi and has a gauge letting you know what leakage percentage you have). Here's a link to Summit's tester:
http://store.summitracing.com/default.asp?Ntt=leakdown&Ntk=KeywordSearch&DDS=1&searchinresults=false&N=0&target=egnsearch.asp
A cracked ring could cause too much pressure in the crankcase and will start blowing oil/smoke out of your breathers ... I hope it's something smaller though for you ...
Good Luck,
Brian

[nova]

Thanks I'll give it a wirl and check. I have a bad feeling that I may have a bad/cracked ring or something.. of course pulling off the headers and checking sucks but much easier than pulling the motor.