Diagnostic Dilemmas: Cams, P&Cs, and Heads

[AlexGross]

So I have been working for a while on my first top-end rebuild, and have finally reached the point where I need to decide which parts need replacement, which need professional cleaning and/or machining, and which parts I can clean and refurbish myself. As I mentioned, this is my first attempt at a rebuild and hence I have very little confidence in distinguishing between a part that is worn but OK and a part that is beyond repair. I therefore humbly request any opinions/advice that you might be willing to give me.

Part #1: The Heads
Based on the service records and my preliminary inspection, the heads appear to be in great shape. The valve guides are relatively new (30,000 miles), the valve margins look ok, and the mating surfaces seem to be in very good shape. However, I am still inclined to send them out for a professional cleaning and a professional opinion. What I would like to avoid is having the head shop try to convince me that my valves are shot, the seats need to be reground, etc. when they might be just fine. Does anyone have an opinion on a good head shop in the Seattle area?

Heads:

Intake Port/Valve:

Exhaust Port/Valve:


Part #2: Camshafts & Cam Housings
I found significant pitting on a couple of lobes on one of my camshafts, and I am just wondering if this pitting is severe enough to warrant a regrind. Also, while I know that a reground cam must be matched with reground/reworked rockers, is it prudent to regrind the other cam/rockers if I am regrinding one set?

Cam Pitting:


I also found pitting in a couple of the rocker shaft bores (I imagine from a PO's attempts to work remove stubborn shafts), but I am thinking that I can prevent any minor leaks by installing the rocker arm shaft inner seal when I put it all back together...any thoughts?

Part #3/4: Pistons and Cylinders
When I got my first look at my P&Cs I was very happy with what I found. The cylinder bores are slightly magnetic (Nikasil), and the cross hatch looks like it's in very good shape. The pistons and rings only have 30k miles on them. Here are my thoughts on how to clean and inspect these parts:
-Should I try to clean them with them still in the block?
(or)
-Should I pop the cylinders out of the block with the pistons in them and then clean them?
(or)
-Should I remove the P&Cs, separate them, and clean then them?
My concerns are that if I remove the pistons and cylinders, I run the risk of allowing debris into the case (I would really, really prefer not to split it). Also, if I take the pistons out of the cylinders to clean them, is it possible to re-use the relatively low-mile rings?

Cross-Hatch:

Right-Side P&Cs:


Thanks for your help guys! I am trying to learn all that I can about this awesome machine, and this forum has been invaluable so far during my rebuild.

Alex

[Flat6pac]

Having the heads done at a reputable shop should be in order because you dont know what was done last time they were in the shop. This is the wear spot of the whole engine. You need to remove the heads because you have leakage between the heads and the cam carrier from inferior sealant. I use Aviation Permatex strictly in that area.
Instead of spending money on those cams just get another pair. 2.7S cams should be very inexpensive. Look or WTB on the for sale section.
If you are not using your air injection, remove the injectors and install 10mm fine thread bolts to clean up the area.
Cleaning the combustion area of the pistons will accomplish what?

Bruce

[AlexGross]

Thanks Bruce,

I am going to send out the heads once I track down a good shop. I think a lot of the oil gunk and build-up that was visible in the photo above was due to leaky oil return tubes...in fact the last time the car was run, there was a great cloud of white smoke due to oil leaking from the oil return tubes and right-side valve covers onto the heat exchangers--this was part of the motivation for the top-end refresh. That being said, I agree with you about the heads...the primary purpose of this rebuild is to attempt to make a leak free, reliable top-end, and having clean, refurbished heads is an integral part to this goal. Concerning the air injection, I have removed them and am planning to plug the holes as recommended.

One question about the cams: if I get new cams (or more likely good used cams), will I need to also replace the rocker arms or at least have the old ones hardened and reground? For what it's worth, the rockers have no pitting or troubling wear patterns.

As for cleaning the pistons and cylinders, my question was pertaining more to the cylinder bores. Do you think I need to de-glaze them (with soap and water and a scotch brite pad)? My desire to clean the combustion area on the pistons was based on my rampant ocd more than anything technical...I just know that it would bug me later on if I were to slap freshly cleaned heads, new cams, new headers, etc. onto pistons caked in carbon.

Thanks again for your help!

Alex

Cam Tower/Head Mating Surfaces:


Air Injection...Removed:

[lindy 911]

Unless you intend to pull the cylinders and re-ring the pistons, deglazing the cylinder walls is not useful. The rings are already seated and deglazing is intended to prepare the wall surface for the new rings.

If you change cams it's a crap shoot using the old rockers without freshening. It's not expensive to have the rockers resurfaced. The idea is to get the foot square with the center line of the cam so the rocker doesn't ride on one edge or another.

As far as shops in your area; John Walker or Steve Weiner (sp?) will not "sell" you anything. They are both straight shooters.

[AlexGross]

Thanks Lindy,

Thats the info I was looking for concerning the P&Cs. Before the tear-down, the engine started and ran well and didn't produce any black smoke so I assumed that the rings were in good condition, but I unwisely didn't do any leak-down or compression testing before the initial tear-down. Based on the fact that the pistons and rings have only 30,000 miles on them I'm just going to leave the P&Cs in the case and clean the exteriors as well as I can. I spoke to John Walker today about getting my heads done, and he thinks that he might also have some 2.7 S profile cams in his shop as well--two birds with one stone as they say . I'm hoping that my heads won't need to be fly cut or require new valves/guides, but I am slowly coming to terms with the fact that I am going to have to bite the bullet and spend some money to get this rebuild where I want it to go...

Thanks again,

Alex