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Discussion Starter #1 (Edited)
Hello to everybody.

I have a 455 pontiac with a comp cam and lifters.

I have had an on going issue with a lifter noise. After taking off the valve cover i noticed that the rocker arm was lose. I tried to tighten the rocker arm but it will not tighten any more. There is still quite a bit of play in the rocker and its real annoying ticking noise. I was just curious if you guys happen to think if its a bad lifter or flat lobe on the cam?

I'm going to be changing my intake soon and I figured I might as well throw in a new set of lifters. When I pull out the lifters will i be able to see if a cam lobe is worn completely flat?

Car does run good except on the road at high RPM's it will studder occassionaly.
 

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run the engine with the valve cover off on that side and observe to see if that rocker arm is getting less left than the others
 

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Loosen the rocker, turn the engine over by hand until the pushrod is either at TDC or BDC, mark it then turn the engine over by hand until it is exactly opposite, mark it. Pull it out and measure between the marks...if you have a bad lobe you wont have any measurement...if a bad lifter you will. Now assemble everything and start it, compare the position of the rocker with the rest of them, if it is lower (pushrod side) than the rest it is most likely a collapsed lifter.
 

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Flat lobe almost certainly. DO NOT RUN the engine any more. You are taking a chance on circulating all that cam material through the engine. I am not sure about the pontiac, but chevy engines have a bypass if the filter becomes plugged......say with cam lobe material. Once that happens all the trash goes to the bearings. Take that thing apart and see what is going on.

Chris
 

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Discussion Starter #6
Ok thx you all for your advise. I will take the valve cover off and try the simple procedures described first. All else fails the intake is coming off anyways. I will post results later.

Thanks again...
 
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