flat cam lobe

[boosted1stgen]

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So i finally had my car up and running after it sat for a few years, seemed to run okay, but it had a miss at idle and when warm a ticking coming from the head. So after checking it out i pull VC off and notice the lobes leading up to the top on both cams have flat spots some on both sides, some on one, and some didnt. Since they have to come out anyway i pulled one of the cam caps to find scouring, my question is what could have caused it and what should be replaced? Cams, lifters, rockers?

 

[91-GS]

Can's say much about the cam, but as far as everything else goes, you can clean the lifters (and even free up stuck ones sometimes), and on the rockers you should check that all rollers are turning freely and clean/replace ones that don't.

How to clean lifters: http://www.dsmtuners.com/threads/diy-lash-ajusters-lifters-cleaning.365986/

 

[boosted1stgen]

Thank you 91-gs. I actually just cleaned all the lifters the other day, and they didnt seem too bad. the rockers all turn freely but some of them the roller part has a bluing color to them, kinda like they were overheated. They are the same ones from before the blown headgasket, so could be from that also.

 

[TurboAnything]

I do not see any alarming wear on any of the parts. Typical for I high milage motor.

 

[boosted1stgen]

Well i did a compression check and it was 90 across the board, adding oil to cylinder did not affect it, the head had all valves replaced with a valve job, timing is right too. Any thoughts?

 

[AllanL]

aren't the cams supposed to be that shape, leading to max lift? something to do with accelerations and ramp rates, i guess...

 

[boosted1stgen]

Its supposed to be a smooth transition, this one isnt smooth to the top its slightly concave almost

 

[Greedy Pimp]

If you look closely it looks like a bump on the second pic , not a smooth transition, if that's what your talking about.

 

[JacksonAuto]

Looks normal. If you degree cams on a regular basis you'd see some wierd stuff. You'd be amazed how much the lobe opens and closes for various reasons.