87350IROC

iTrader: (2)

Guys,

This weekend I was at Pacific Raceway doing a high performance driving day. This included significant time on their 2.25 mile road course.

I found that driving on the road course caused my oil dipstick to "pop up" about 1" and let a small amount of oil come out and splash onto the valve cover and header. Not good. Also, the track is left turn dominated which didn't help seeing as the dipstick is on the passenger side. Based on my research this sounds like piston ring blow by. Now I have never had this happen during hard street driving or drag racing. So I am not convinced its to bad. What do you think? Has anybody else had this kind of problems road racing?

Details on motor.

355TPI with ~5000 miles on rebuild
does not use any oil
stock PCV system
stock dipstick

xpndbl3

iTrader: (5)

PCV doesn't do anything at WOT, what does the breather in your other valve cover look like? Be happy the dipstick blew out and not some gaskets like the oil pan instead from too much pressure in the crankcase.

87350IROC

iTrader: (2)

The whole engine has the stock CCV setup. Which is PCV in the driver valve cover which is connected to a hose that goes to the intake manifold. On the passenger side there is a hollow elbow sticking out of the valvecover that is connected to a hose that goes to the throttle body. My understanding is that pre-throttle blade air gets ducted into the passenger side valve cover then gets removed by the PCV on the drivers side.

I'm guessing the PCV doesn't work at WOT because there is no vacuum to pull the valve open?

So there must be some blow by in all engines. How is that pressure supposed to escape at WOT?

AlkyIROC

It gets forced out wherever pressure can escape. For drag racing, header evacs are the most common way to let the crankcase vent. I use an electric vaccum pump until I can find a way to mount my belt driven pump. Even at WOT, the electric pump can't pull the crankcase pressure out fast enough but it all goes into a puke tank so I just drain off the condensation after every run.

A simple way to keep the dipstick secured is with a straight spark plug boot.

87350IROC

iTrader: (2)

So I'm still a little fuzzy guys. If I understand what you are saying, it sounds like my PCV is working as designed. Its just that the stock systems was never designed for long WOT runs?

So on a completely stock engine in good working order, where does crankcase pressure go during a WOT run.

It seems like if pressure got high enough, would it just push up the tube that goes into the passenger valve cover and get dumped into the throttle body?

xpndbl3

iTrader: (5)

sounds like you need to run a breather in the passenger valve cover and see if it starts smoking a lot when under WOT, the factory PCV system can't push enough air through the tiny factory hose in the pass. valve cover if it's pushing out the dipstick.

87350IROC

iTrader: (2)

So it seem like either:

Excessive blow by

or

Stock setup not designed for road racing abuse

thoughts?

Perhaps its time for a leak down test. If only I had an air compressor.

cp87GTA

I'd remove the pvc valve and tube on the other valve cover and install a couple moroso breather caps when racing. I tried using 2 pcv valves thinking it would pull a vaccum on the engine. I kept pushing the front seal out. Went to an header evac system, problem gone. If you put a plug boot to keep the dipstick in, you will blow seals. If you use the breathers you can just swap them back to the pvc system real easy.

darksidez28

I HAVE 91 Z28 CONVERTIBLE W/L98,

Q: WHAT CAUSES THE OIL TO BACK UP THE DIPSTICK LINE AND PUSH THE DIPSTICK OUT AND CAUSE IT BLOW ALOT OF OIL ON TO HEADERS ETC. ALSO WHEN I GET ON IT FROM A DEAD STAND, SHE RUNS THRU 1ST AND 2ND FINE BUT 3RD OR 4TH MAY TRIGGER SOME TYPE OF FUEL SHUT OFF OR IGNITION, EITHER WAY SHE LOSES ALL POWER.

BRIEFLY: I RECENTLY DID THE INTAKE GASKET. BEFORE THIS I HAD NO PROBLEMS WHAT SO EVER WITH ACCEL AND TOP-END. BUT AFTER I HAVE HAD THE OIL PROBLEM AND THE LOST OF HIGHEND POWER.

ANY SUGGESTIONS

darksidez28

also i had this "mechanic" look at it he just played with the timing, now from a dead stand she gets off like her old self, but still same problem with the high end. and if i back off the throttle when it shuts off and slights get back on it again the power is back, and staedy acceleration on high way in 3rd and 4th i pass the mark where it normally would shut off at never hits that point, only under heavy acceleration


i see you mention the drip down test how is it done.


anybody in psl, florida or south florida that might be able to help show me in person whats going wrong