Cam opinions needed - appears to be severely worn (1978 280z)

[johnny haywire]

Well, what started out as the perfect Sunday of wrenching on the Z in 75 degree weather didn't end up so well.

My plan was to adjust the valve clearances on my '78 280z today and here is what I found when I pulled the valve cover off:

[ATTACH=CONFIG]53851[/ATTACH][ATTACH=CONFIG]53852[/ATTACH][ATTACH=CONFIG]53853[/ATTACH][ATTACH=CONFIG]53854[/ATTACH]

The photos are slightly out of order, but the worst is toward the rear of the engine, where there was funk built up along the sides of the lobe (where the rocker doesn't make contact) and some contact areas were also coarse to the touch.

I went ahead and did the adjustment anyway and to add insult to injury, they still tick. About 9 of the 12 were out of spec.

So, my diagnosis is that the cam is shot and the rockers probably are as well. I would really appreciate hearing some opinions from members who have come across this and dealt with swapping out cams/rockers in the past.

It's not my daily driver (though I do drive it quite frequently and have put about 3,000 miles on it since I bought it...oops...), so it can sit until I figure out what to do. The eventual plan was to put a mild cam in there anyhow, so maybe this is the perfect excuse to just go ahead with that.

Many thanks in advance.

Edited June 3, 2012 by johnny haywire
incorrect terminology

[Captain Obvious]

Uhhh... Are there oil holes in the cam lobes? I'm not seeing any in the pictures.

It may just be the way the lobes are situated in your pics, but if not... that's a problem.

[johnny haywire]

There are oil holes. I definitely noticed them while I was doing the adjustment. You can see one in the 4th picture on the 1st lobe if you squint your eyes...

Edited June 4, 2012 by johnny haywire

[Zed Head]

Looks like oil-covered rust to me. Did the car sit for a long time before you got it? Might be worth the time to remove the rocker arms and clean them up with Scotchbrite along with the cam and lash pads to see how pitted they are. Keep them all in order, they need to go back together just like they came off. It might be fine and I'm sure the rust, as a high spot, is screwing up your lash adjustment.

The most expensive part of a cam swap is the rocker arms, I believe. Might do the math before you decide on that route.

[olzed]

What Zed said, You can't run the engine with that rust everywhere. You are going to destroy the rockers, if they are not already.

[johnny haywire]

From what I gather from her old records, she sat for about 14 years before the previous owner brought her back to life. Based on what he did before I got her, (bare minimum to get her running) not much was done. I feel like she's running despite his (and my) neglect. I have no problem pulling it apart and cleaning the rough bits up with scotch brite/steel wool, etc.), but my concern is that once it has worn through the outer-hardened shell of the cam/rockers, the inner materials are softer and will break down, leaving bits of metal to screw up the rest of things.

I guess my question is...should I go with a new top end? I've never come across a valve train that looked like this. If it's fixable/deal-able for a while, I'll ride it out, but I'm concerned about having things break up and clog oil ports and sending tiny bits of metal into places where they aren't welcome.

I know it's not the end of the world, but most of my budget for the car this year is dedicated to strut inserts/springs/wheels/tires, and this sort of changes everything.

Thanks again for all your insight.

Cheers,

- Paul

[olzed]

Clean up the rust, and see how she goes.

Regular oil and filter change might give you some good miles. These engines are tough, and it will be interesting to see just how tough.

[Captain Obvious]

There are oil holes. I definitely noticed them while I was doing the adjustment.

Haha! I think you purposely positioned that cam so that none of them show in your photos.

So as for the rust... If your oil pressure is healthy, then I'd clean it up and run it for a while and see how it goes. From what I've read, being able to hear the valve train on these engines is pretty much expected.

[Gary in NJ]

Looks like you have cam lobe corrosion and spalling (pitting). If this is the case, it can't be fixed, only replaced.

[tlorber]

I'm with the clean it and run it crowd. As long as you remove the debris, you won't cause any damage to the bottom end. That kind of gunk is not unexpected for a motor that has sat for a long time. After cleaning, I'd use a thin detergent oil and change it after 1,000 miles or so. Then pull the valve cover and see how things look

[GreenZZZ]

Oil/filters are cheap. I did a buddies that was sludged and rusty. I adjusted the valves, swapped the oil three times (500 miles per), readjusted the valves. Ran great and was all cleaned out. Yours has no sludge at all...

[johnny haywire]

Thanks to everyone for commenting. I'm thinking I'll just keep going with her as she is and plan for a cam swap over the winter, with periodic checks. If nothing changes, I may not be in such a rush. One point my father brought it up is the fact that since the rust hasn't been polished off after 3,000 miles, there is no metal-on-metal contact, a good thing. The lobes were definitely covered with fresh oil, which I noticed as I adjusted them.

Have any of you ran the engine with the valve cover off? I'd like to do that to make sure none of the oil ports in the cam lobes are clogged, but I'm curious as to whether there will be oil spraying everywhere if I do that.

And for what it's worth, the car has 92,000 miles on the clock. Or 192,000, but I'm inclined to go with the former based on how long the car sat and its condition.