help parts for piston

[basbal2540]

hey i'm new to this and attempting to fix up a 1969 911t, had something that was hitting the piston. Need help with finding out what i should get , nee a set of rings or the one piston a complete gaskit set, new o rings for oil tubes , i have put some pictures to try and help, any advise would help thanks!

[HawgRyder]

Because of the curved look at some of the scars...I would suspect broken rings.
It might also be possible that a washer fell into the cylinder during maintenance.
Bob

[E Sully]

Definitely replace the piston.
How does the cylinder wall look?

[basbal2540]

what size rings should i get/ and what gastkit set? its been modified before so not sure if anything would change

[Bob Kontak]

How does the bore look for the piston that took the beating? How does the head look?

I am seeing a crack in the piston? Correct?

Are you looking for a laundry list of stuff you will need to do a top end? Are you doing a full rebuild? Have you pulled the other pistons?

[911pcars]

Looks like the cylinder ingested something, or perhaps the spark plug electrode might have fallen off. Doesn't take much to redecorate the combustion chamber/piston. Sourcing a single piston assy. should be fairly easy. However, before doing that, inspect the remaining pistons and cylinders to see if they're still in spec. (oil clearance, cylinder wear, piston OD, ring land grooves, etc.). Purchasing a complete new P/C kit might be better in the long run, perhaps less expensive.

Is the rebuild a DIY project or are you farming this out? Makes a difference in the value of your funds. If a complete rebuild is in order, it might be "better" to rebuild an engine with more power potential (2.2, 2.4, 2.7, etc.). However, if this must be a numbers-matching vehicle, then your options are more limited.

You should read and study a couple of recommended books: Anderson's 911 Performance Handbook and W. Dempsey's Porsche Engine Rebuild book (sorry about the inaccurate title, but it's available from this/his website/forum).

Sherwood

[basbal2540]

the other pistons are hood and the cylinder bore had no damage , the head had a little damage the guy working on it said he did a pressure test and it was ok. i have a friend that has worked o alot of cars before doing most the work. What is a p/c kit?

[E Sully]

You need to have the bore of the cylinder measured to see if it is in good shape before anything else. If it is then you can try to find a good used piston in the classified section. P/C kit is piston and cylinder.

[basbal2540]

i found the papper work on the rebuild and they modified to 2.5+ new 90 m pistions and cylinders, does that change what kind of gaskit set i should get?

[basbal2540]

thinking of also changing out the oil pump they have two on here but ones 1k and the other is much cheaper no picture says update kit / any ideas on any other pumps for cheaper?

[911pcars]

Originally Posted by basbal2540

the other pistons are hood and the cylinder bore had no damage , the head had a little damage the guy working on it said he did a pressure test and it was ok. i have a friend that has worked o alot of cars before doing most the work. What is a p/c kit?

Inspection includes measuring as well as a visual look-see. Only way to determine if all clearances are in spec.

A piston/cylinder kit includes (6) new pistons, cylinders, rings, piston pins. Consider if the cost to rebuild your engine, including parts exceeds the cost of new components.

Whenever you get inside an engine, there are several slippery slopes to consider (i.e. how far you want to go to rebuild it "correctly"). Each builder has to decide based on "good enough" or "correct methods" with lots of gray area/nice to have decisions in-between.

Minimally, you could inspect the piston and other parts and reuse it if otherwise good; reinstall the existing rings (if still in one piece) and be on your way. YMMV (your mileage may vary = up to you).

I suspect you initially disassembled in the first place because of some noise in that cylinder that resulted in the piston damage. How was it running before?

MHO,
Sherwood

[basbal2540]

it at for over 15 years had it running hear the noise and shut it down shortly after, not wanting to get int alot of money with it..

[tharbert]

From his picture, those are 90mm (~3 17/32"). A 69T had 80mm bore (3 5/32"). Maybe it has been reworked into a 2.7?

Here's a long thread on p/c sets including discussion about the quality controlled sets from Charles Navarro, LN Engineering
or the Chinese made QSC sets. I guess it really comes down to your goals with the engine and your budget.

[Bob Kontak]

Originally Posted by tharbert

Maybe it has been reworked into a 2.7?

Or a 2.5+ liter engine maybe like the paper work says?

What is the piston travel on the 69 80mm's? Then the displacement can be backed into (not by me but someone can).

[Bob Kontak]

Originally Posted by Bob Kontak

Or a 2.5+ liter engine maybe like the paper work says?

Original bore and stroke - 80mm x 66 MM = 1.991 L

Modified bore and stroke - 90mm X 66 MM = 2.518 L

[basbal2540]

what kind Engine Gasket Set, do i get then?

[Bob Kontak]

Originally Posted by basbal2540

what kind Engine Gasket Set, do i get then?

Here's the deal. You have a 2.0 liter case. You have 2.7 liter pistons and cylinders.

It's been done before but this is not routine for lots of folks in this forum.

We have no idea of the heads and cams your engine is running.

What type of research work have you done to determine what you need aside from posting a request here?

I hope you can get an easy answer but I would slow down - a whole lot - get some reading under your belt - then proceed with part selection.

Here is the 1965-1969 parts catalog (2.0 engine).

http://www.porsche.com/all/media/pdf/originalparts/en/E_911-1_KATALOG.pdf

Here is the 1974-1977 parts catalog (2.7 L engine).

http://www.porsche.com/all/media/pdf/originalparts/en/E_911_77_KATALOG.pdf

Start by cross referencing your engine parts (heads / cams / pistons) and gaskets against these catalogs and see what you have - or don't have.

[911pcars]

Originally Posted by basbal2540

i found the papper work on the rebuild and they modified to 2.5+ new 90 m pistions and cylinders, does that change what kind of gaskit set i should get?

I missed that detail earlier. If indeed these are 90mm pistons, they appear to be RS type. A complete set is typically $3000 or so, thus sourcing just one P/C assembly might be a bit tricky (not common). If you're on a budget, I would suggest taking a closer look (a knowledgeable tech person/engine builder suggested) and see if the damaged piston can be made whole and reusable. Option 2 is to find a single replacement RS piston or piston/cylinder assy. BTW, not all 90mm pistons are the same (for example, 90mm CIS pistons have a different crown shape).

Sherwood

[tharbert]

You could probably measure your stroke in the cylinder sleeve. 66mm is the original crank throw. Here's a table for the years, models and basic specs.

But, yeah, before you start buying, you need to be very sure what you have. It can get expensive with restocking fees and double the shipping alone. You know, at this point, it's absolutely not original.

I'm kind of in the same boat as you: unsure of the internals. I plan to document and do a lot of measuring as I dig into my engine.

[Bob Kontak]

Originally Posted by 911pcars

If indeed these are 90mm pistons, they appear to be RS type....................... . If you're on a budget, I would suggest taking a closer look (a knowledgeable tech person/engine builder suggested) and see if the damaged piston can be made whole and reusable.

Outstanding information. I do now remember reading in Bruce Andersons book about the RS pistons and his caveats. Maybe I am thinking about some other odd-ball piston but I do recall some info on this.

How can you tell they are RS pistons?