Camshaft wear-pics. Do I need to recondition?

SP2 · 11-07-2006, 11:42 PM

Hello. I took my 81SC 3.0 stock engine out. I want to change all the seals, new clutch and repair the tranny. When I got the engine up into the stand and flipped it upsidedown, I removed the valve covers and could see in and look at the camshafts. I started this project, and my original plan was to NOT do any kind of rebuild because my PPI showed good compressions.

The first 2 photos show the cam lobe at cylinder 4. You can see the pitting. The next two photos show how dark colored the lobes with cyl 5 and 6 are. Does this mean they were at one time rebuilt and reground? I can see no pitting with 5,6. The last 3 photos show cyl 1,2,3 cam lobes. They are shiny chrome colored like cyl 4, not dark like 5,6. But there is some staining and I don't know if this shows bearing wear.

What do you think? I am a total newbie mechanic. The car was running well prior to this, but I had a big leak from the front of the engine at the classic t-stat, breather cover and oil sender. My PPI also told me I needed a new clutch. I am trying to avoid a rebuild. Do you think my camshafts need to come out?

Thanks!

cnavarro · 11-08-2006, 04:50 AM

How long do you plan on keeping it? That really is the question that should determine how far you want to go. I have made the same mistake to try to fix or update everything, only to sell the car shortly thereafter - not a good return on your money.

Were any of the valves tight or loose? Cut apart the oil filter, see if there is any wear metal accumulated there as well. You might just want to adjust everything, change the oil, and monitor.

SP2 · 11-08-2006, 05:54 AM

I will keep it forever. Seriously. I am forty and have a history of keeping my cars. This being my first Porsche that I worked on, it's a keeper. And even if I did let it go, I have 3 nephews and a niece lined up for her.

That having been said, I am not averse to taking the engine out and redoing things in the future. I just would like to avoid anything catastrophic to the engine. Charles, what sort of things would I be monitoring if the camshafts or rockers began to fail?

Thanks,

cnavarro · 11-08-2006, 06:11 AM

I would just keep an eye on the valve lash, just that it isn't opening up. I would imagine if you do end up pulling the engine apart for a rebuild or upgrade, at that point I would regrind the cams and recondition the rockers, but it's probable that the cam has been like that for a long time and it's also probable that nothing will fail catastrophically at this point for that same reason. Has the engine been rebuilt at any point to your knowledge?

I remember there being a thread some time ago with cam faces with similar wear and if I remember correctly, the verdict was not to worry about it. It would be great if someone like Camgrinder would chime in, since he reconditions and grinds new cams all day - you might want to do a search or PM him.

camgrinder · 11-08-2006, 10:01 PM

Looks like typical wear for a 78 - 81 SC. usually its the right side camshaft furthest away from the tming gear. Eventually it ends up on all the lobes.
Some of the pictures show the nose of the lobe (the ones with the pitting) and other pics show the heel (the dark pics of the bottom of the lobes)
If you turn the engine over and watch the noses, you might find more pitting like shown in the first pic.
Good news is the cams are easily reground. You can even upgrade to the 964 profile and get a little more power out of the engine.

SP2 · 11-08-2006, 11:28 PM

Thanks John. But does this mean you think these cams need to be taken out now?

If you regrind the cams, does this mean the lobes are actually smaller than the original, or do you build them up first and then grind them down. Is it the same idea with the rockers? My mechanic here John Walker told me not to get them smaller. I read your website and I am interested, but I would like to put this off for a while if possible. Why? Because I am not sure if I have the skills to put them back in correctly. I am a little intimidated by this notion.

Can you say something more about the 964 cams? Is it compatible with my CIS?

Thanks again!

camgrinder · 11-09-2006, 07:14 AM

James,
If you let it go the wear will only get worse. You need to inspect the rest of the lobes closer.
I do not "build up" or "weld up" camshaft lobes on the 911 Porsche. I have new billets for most Porsche applications. I might weld up a rare 906 or RSR cam if the customer wants to keep it original, and the cam had failed etc.
The 964 profile ground onto the SC or Carrera cams is very popular. The base circle reduction is minimal and causes no problems. These cams work fine with cis.

Do a search for "964 cams" on here.

SP2 · 03:23 PM

Thanks John! (camgrinder)

I think I will take your advice and remove my cams. The more I re-read how to remove and replace the cams and the rockers, the more I can see myself doing it. I realize the hard part is replacing and then retiming the cams. My other option is to leave my old ones in, get the car running, then let JW put them in for me. I went by John Walker's shop today. He sees this too. You can ask him what he thinks. But JW did have alot to say about what an upgraded cam would have on performance.

I am studying the pelican BBS search on the subject. There is alot of good data out there shared by pelicanites regarding the torque curves with the various cams. The 964 cam has caught my eye. JW mentioned the 20/21 cams. He said he installed this into a car with SSI's and a Monty muffler and it was like a fire breathing dragon. Lo and behold, I have SSI's and a Monty ready to go in.

Now if I could only get that one broken exhaust stud out....