Pitted cam lobe question and valve ticking question

[geostasis]

I took my somewhat long in the tooth (1988) 911 to the shop earlier this week for a service and a new clutch. Since the engine was dropped anyway, I also asked for a valve adjustment since I have been getting some distinct clacking/ticking.

Got the call yesterday PM: one of the lobes on the right cam has a pit (wear?) and needs to be replaced. Since one needs to be replaced, I'm getting advised that I should replace both cams, all the rockers, all the chain rails, valve springs, and the valves.

I'm in 3K right now and would like to spread the repair cost over some time, so a couple of questions:

1) What is the risk of driving with a pitted cam lobe?
2) Would cam pitting cause excessive ticking, or should I be suspicious about other causes such as valve guide wear?
3) What questions should I be asking as I figure this out?
4) Are there any engine rebuild shops which are highly recommended for street vs race/track cars? Price is important, but not the only consideration.

I have the Wayne Dempsey "How to Rebuild and Modify Porsche 911 Engines 65 - '89" and will be reading it cover to cover this weekend.

Other stats:
* 1Qt Oil per 1000 miles or so
* Car is a weekender vs daily driver, but I do occasionally take longer trips

Thanks all

[Steve@Rennsport]

Hi:

You did not state how many miles are on your car and thats an integral part of this discussion's best answer,...

Cam lobe damage is not to be take lightly as that displaced metal is in the oil. I would definitely have both cams repaired, have the rockers rebuilt, and do a regular valve job if you can afford that part now.

Without knowing mileage, one cannot comment about guide wear but if you are over 100K, it would be very foolish not to do a proper valve job and install new guides and likely, exhaust valves.

One cannot make any shop recommendations without knowing where you live,....


For the benefit of others who may follow this thread, this is a problem thats been surfacing since the EPA mandated the changes in oil formulations. You should do a search to read what has been written on this subject as some of that information is valuable.

Some of these problems can be attributed to clogged spray bars due to infrequent oil changes, but one of the biggest contributors is the loss/reduction of the ZDDP EP additives in motor oils.

[geostasis]

Steve,

You are absolutely correct. I have failed to provide some critical info. Approx. 106K miles. Located in Portland, Oregon.

Right now, what I am trying to figure out is repair vs replace vs rebuild vs ???.

What I was presented Friday was the price of replacing all parts with new OEM Porsche parts. Two cams, new rails, new chains, new rockers, new valve springs (don't know if I missed anything). This is the shop's recommendation, and I was concerned enough about the amount quoted that I needed to think about it over the weekend.

What I'm trying to figure out is whether I can repair/regrind the cam and rocker and have a good interim solution. I don't know that I can jump off into a top end job right now. Intellectually, I know that that's coming due, but I'd prefer to stuff some money away for that over the next few months. I can't afford 12K worth of top end work (that's the high number, P&L), and 5K worth of cams, rockers, valves et all (also P&L) is pretty painful right now. That's my dilemma.

I'm far better informed today than I was Friday after doing some research, but I still am not very sure what my various options might be. I really appreciate your advice, and the comments from the forum members. Good stuff!!!

[Steve@Rennsport]

Do a leakdown test before you begin. Barring any big surprises, you should be able to do all the things I suggested for around $6-7K. At 106K miles, your P/C's ought to be in fine shape,......

Remember, we never have the money to do something right, but we always have the money to do it all over again.

If you have questions, you can e-mail me directly about who you are contemplating doing all the work.