Pariah91
Probationary Member
- 2
- 0
- Mar 19, 2009
-
Lancaster,
California
Hey everyone this is my first post here. I realize this is probably the wrong section but It forced me to post in the newbie section. So here is what's going on.
I have been having issues with my lifters pumping up when I use my crower 272/272 cams. After I bleed the lifters the car runs great for about 5 minutes but it slowly starts loosing compression from the valves being forced open by the lifters. I can put the stock cams back in and the compression is perfect and the lifters don't over pump.
So here is what I have done so far. I have checked the oil pressure in the head which is good. I have sent the cams in for a new pair thinking they were bad but the new ones have the same problem. I have shortened the valve stems which didn't help, and I have replaced the stock valve springs with crower springs and used .060 shims which didn't help.
The engine is brand new and has about 1000 miles on it. This problem has been driving me insane and nobody seems to have ever had this problem.
Here is a couple pictures of the valves when I removed the head to change the springs.
As you can see the intake valves seem to have some carbon build up on them. I'm not sure if that's normal or not. I believe the intake valves are the main ones being forced open because I start to loose all my vacuum. Thankfully the valves haven't been bent from sticking open.
I hope you guys can help me figure this out.
Just thought I would add that even with the stock cams in I could only run a 13.9 at 98 in the 1/4. I was running 20psi on 91 octane with no knock at 10.5 afr. I'm hoping that has something to do with all these problems I'm having with the 272's.
I have been having issues with my lifters pumping up when I use my crower 272/272 cams. After I bleed the lifters the car runs great for about 5 minutes but it slowly starts loosing compression from the valves being forced open by the lifters. I can put the stock cams back in and the compression is perfect and the lifters don't over pump.
So here is what I have done so far. I have checked the oil pressure in the head which is good. I have sent the cams in for a new pair thinking they were bad but the new ones have the same problem. I have shortened the valve stems which didn't help, and I have replaced the stock valve springs with crower springs and used .060 shims which didn't help.
The engine is brand new and has about 1000 miles on it. This problem has been driving me insane and nobody seems to have ever had this problem.
Here is a couple pictures of the valves when I removed the head to change the springs.
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As you can see the intake valves seem to have some carbon build up on them. I'm not sure if that's normal or not. I believe the intake valves are the main ones being forced open because I start to loose all my vacuum. Thankfully the valves haven't been bent from sticking open.
I hope you guys can help me figure this out.
Just thought I would add that even with the stock cams in I could only run a 13.9 at 98 in the 1/4. I was running 20psi on 91 octane with no knock at 10.5 afr. I'm hoping that has something to do with all these problems I'm having with the 272's.
