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Old 10-12-2008, 10:03 PM
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stuck valve problems

I have a 455 olds with e-brock aluminum heads,fully rollerized comp cam, grind #xr276hr-10,approximate compression of 9.8:1 E-brock 800 cfm.When the engine was first done (80 miles on it now)it seemed to run very strong,since then the timing and carb were taken to be set up better, on the way home one rocker backed off (not sure what happened)re-adjusted it seemed to run rough after, I brought it to get its 3" exhaust put on and it seemed to idle worse and have more issues . I have very erratic and low vacuum(needle bobbing back and forth between 11" and 7") I just finished doing a leak down test and have found that the suspect cylinder does not register very much air in the cylinder with compressed air.Have since concluded that it is the intake valve. Now i'm wondering what the cause could have been and what is my next step? Could this valve be bent or most likely just stuck. Is there anyway to fix this without pulling the head.Can I be sure this is only a stuck valve? Any opinions and direction would be appreciated .
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Old 10-13-2008, 12:30 AM
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Ok brand new engine with very expensive heads....you don't want to screw anything up here. Suspect cylinder.....I would bring the piston up to TDC, since it won't hold air stuff a small diam. rope through the spark plug hole to keep the valve from falling (if it's not stuck).

Then remove the valve spring and retainer and see if you can move the valve up and down freely. If it really is stuck or bent then you will have to remove the head for diagnosis and repair. You also need to address the reason for the rocker arm nut backing off, IF it was adjusted properly it shouldn't have backed off. I would also check the rocker arm geometry, push rod length and check to see if the valve hit the piston....in other words, CHECK everything.
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Old 10-13-2008, 05:34 AM
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If you did the leak-down test properly, and found the leakage past the intake valve, then the next step is pull the head.

sam-missle
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Old 10-13-2008, 08:54 AM
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stuck valve problems

before tear down , as stated earlier , remove the spring and can you rotate valve stem to check for bent valve and how much play you have .
you may also have to good of valve seal not letting any lube buy .
intake valves with new guides don't require a better seal .
if it's not warped , i'd leave the seal off and run , but be aware of the other valves seizing up , as you state few miles on engine .

i had this happen on my 455 olds and i got rid of the seals .

also if there's bronze guides , never run without water in motor , they will bind the valve .
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Old 10-13-2008, 11:32 AM
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It would be a good idea to pull the intake manifold and inspect the lifter
and cam lobe. It's possible that lobe was damaged when the rocker arm
was loose.
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Old 10-13-2008, 03:45 PM
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Have you tried to back off the Rocker in question and see if you then have compression?
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Old 10-13-2008, 04:23 PM
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Quote:
Originally Posted by hammerhead
I have a 455 olds with e-brock aluminum heads,fully rollerized comp cam, grind #xr276hr-10,approximate compression of 9.8:1 E-brock 800 cfm.When the engine was first done (80 miles on it now)it seemed to run very strong,since then the timing and carb were taken to be set up better, on the way home one rocker backed off (not sure what happened)re-adjusted it seemed to run rough after, I brought it to get its 3" exhaust put on and it seemed to idle worse and have more issues . I have very erratic and low vacuum(needle bobbing back and forth between 11" and 7") I just finished doing a leak down test and have found that the suspect cylinder does not register very much air in the cylinder with compressed air.Have since concluded that it is the intake valve. Now i'm wondering what the cause could have been and what is my next step? Could this valve be bent or most likely just stuck. Is there anyway to fix this without pulling the head.Can I be sure this is only a stuck valve? Any opinions and direction would be appreciated .
I'd contact Edlebrock before proceeding to see if they will warranty this.

Bogie
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Old 10-21-2008, 10:33 PM
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If any one was wondering what happened to my heads it turned out to be a collapsed lifter,the reason the vave wouldnt seal is because it was reset thinking it only backed off causing the valve to hang open a little. Lifter was 1/4 " down from snap rings and would not come back up. Will replace and hopefully everything else will fall into place.Hopefully comp will warranty it. Thanks for your comments,helpful.

Last edited by hammerhead; 10-21-2008 at 10:39 PM.
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