Crankcase pressure
Thread Starter
6th Gear
Joined: Oct 2011
Posts: 6
Likes: 0
From: Fort Worth Texas
Crankcase pressure
I need some insight.
I have a 78 L-82 that still had the original motor three years ago when I upgraded the top end with Edelbrock Performer heads, cam and intake. The bottom end seemed to be okay.
I immediately began blowing valve cover gaskets, then intake gaskets (front and rear) (tried the rubber gasket and went back to silicone), rear main seal and so on. I was not having this problem before the upgrades.
I took it apart several times looking for the problem. Edelbrock said "just put a breather cap on the valve cover instead of the oil filler cap", that didn't help. The original breather is still on it with the factory vent system intact. The pcv valve has been changed twice.
After spinning an insert I decided to make a stroker out of the original and built a temporary motor out of a 73 vette with new 40 over pistons, turned crank, balanced rotating assembly, new Performer cam, reused the heads and intake.
I now have excessive crankcase pressure in the new motor. Blowing oil from around the distributor and dip stick tube and finally blowing the rear intake gasket.
All insight and advise will be appreciated.
GH
I have a 78 L-82 that still had the original motor three years ago when I upgraded the top end with Edelbrock Performer heads, cam and intake. The bottom end seemed to be okay.
I immediately began blowing valve cover gaskets, then intake gaskets (front and rear) (tried the rubber gasket and went back to silicone), rear main seal and so on. I was not having this problem before the upgrades.
I took it apart several times looking for the problem. Edelbrock said "just put a breather cap on the valve cover instead of the oil filler cap", that didn't help. The original breather is still on it with the factory vent system intact. The pcv valve has been changed twice.
After spinning an insert I decided to make a stroker out of the original and built a temporary motor out of a 73 vette with new 40 over pistons, turned crank, balanced rotating assembly, new Performer cam, reused the heads and intake.
I now have excessive crankcase pressure in the new motor. Blowing oil from around the distributor and dip stick tube and finally blowing the rear intake gasket.
All insight and advise will be appreciated.
GH
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
I need some insight.
I have a 78 L-82 that still had the original motor three years ago when I upgraded the top end with Edelbrock Performer heads, cam and intake. The bottom end seemed to be okay.
I immediately began blowing valve cover gaskets, then intake gaskets (front and rear) (tried the rubber gasket and went back to silicone), rear main seal and so on. I was not having this problem before the upgrades.
I took it apart several times looking for the problem. Edelbrock said "just put a breather cap on the valve cover instead of the oil filler cap", that didn't help. The original breather is still on it with the factory vent system intact. The pcv valve has been changed twice.
After spinning an insert I decided to make a stroker out of the original and built a temporary motor out of a 73 vette with new 40 over pistons, turned crank, balanced rotating assembly, new Performer cam, reused the heads and intake.
I now have excessive crankcase pressure in the new motor. Blowing oil from around the distributor and dip stick tube and finally blowing the rear intake gasket.
All insight and advise will be appreciated.
GH
I have a 78 L-82 that still had the original motor three years ago when I upgraded the top end with Edelbrock Performer heads, cam and intake. The bottom end seemed to be okay.
I immediately began blowing valve cover gaskets, then intake gaskets (front and rear) (tried the rubber gasket and went back to silicone), rear main seal and so on. I was not having this problem before the upgrades.
I took it apart several times looking for the problem. Edelbrock said "just put a breather cap on the valve cover instead of the oil filler cap", that didn't help. The original breather is still on it with the factory vent system intact. The pcv valve has been changed twice.
After spinning an insert I decided to make a stroker out of the original and built a temporary motor out of a 73 vette with new 40 over pistons, turned crank, balanced rotating assembly, new Performer cam, reused the heads and intake.
I now have excessive crankcase pressure in the new motor. Blowing oil from around the distributor and dip stick tube and finally blowing the rear intake gasket.
All insight and advise will be appreciated.
GH
I would do a leak down test at TDC to see if there is a ring seal issue. Was the cylinders bored off an usnsquared deck and was your block plate honed honed?? Also they may not have used the proper finish for the rings you are using!!
Make sure you have the breather hose that goes to the air cleaner from the valve cover as most guys delete this hose because of an after market air cleaner
Last edited by BLOCKMAN; Oct 14, 2011 at 06:01 PM.
Safety Car
Joined: Oct 2007
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Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
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be cautious of cheap aftermarket valve cover grommets, I had some and they would seal up allowing the crankcase pressure to build, after I modified the Grommets/oil baffle, problem was solved.
