Two rebuild related questions...

[M491Cabriolet]

Hi. I have my 1972 911T's original engine out of the car, and another 2.4T engine in the car now running. I am about to hand my original engine over to a mechanic to rebuild, and I want to be sure of what I am giving to him. I don't want to tear it down though. It will be helpful to him to do that himself. But I don't know if this engine was ever rebuilt. If so, I think there is the possibility that it might have been upgraded to S or E internals, or even to 2.5 or 2.7.

Background: The original engine has been sitting for about 20 years (installed in the car), hostage of a mechanic in an incredibly long mechanic's lien case. I bought the car from the mechanic not too long ago, feeling bad for the original owner, but happy for me. The car was basically a time capsule, but after so many years of disuse, the engine was toast. I put the current engine in so I could drive the car.

Now I began just yesterday to strip the original engine down to the longblock in preparation for the rebuild. I just noticed that it has Carrera chain tensioners and SSI heat exchangers on it. To me, this means the previous owner was the kind of person who might perform some interesting upgrades to his engine. Consider, these visible upgrades were already made in 1989.

Question 1: Is there any way to tell from the outside of the longblock if cylinders are 911T or 911E or 911S? I mean, would 911T cylinders, being cast iron, look all rusted and scaly and alunimum finned 911S and E look uncorroded? All I see is that they are Mahle and free of rust.

Question 2: Is there any way to pull off the cam tower and heads without removing the cams? I literally just want to have a peek to see what kind of pistons are inside and put it back together. It should be obvious from the shape of the top of the pistons and their valve pockets whether these are the stock 2.4 911T pistons, or something else.

Thanks for reading this far. Any information and detailed instructions would be highly appreciated. Thanks in advance!

[OldTee]

Buy our hosts book "How to Rebuild & Modfy Porsche 911 engines 1965-1989" by Wayne R. Dempsey AND "Porsche 911 Performance Handbook" by Bruce Anderson AND the Bentley for your model series.

Ans to Q2. No.

[M491Cabriolet]

Thanks for your advice (from me and, I'm sure, the host). I already bought the first two books from Pelican Parts years ago. I have both the SC and Carrera versions of the Bentley books too. Keep in mind that Bentley, to my knowledge, did not make a minual for anything earlier than the SC and, as I said, I have a 1972 911T. So, my particular model would not be discussed in a Bentley book. In addition to the above books, I even have all of the factory workshop manuals and thirteen million other books.

Unfortunaltey, I did not find my answers in any books. If you have a page number I should refer to, please let me know. The problem is, all of them seem tell you how to tear down engines, and rebuild them, which is what I said I do not want to do. I want my mechanic to do that.

*** All I'm trying to accomplish is to see what pistons are in my engine before I turn it over to the mechanic. So I asked if there is any way to remove a cam tower without taking out the cam. Do you know if this is possible (without damaging the engine)?

*** I also asked a question about trying to ID cylinders based on external appearance and corrosion.

I figured I'd ask here because someone must have unpublished knowledge in regard to both of these questions. Anyone, please???

[OldTee]

Looks like you can remove the cam tower and three heads as a unit with the cam shaft in place. But to do that you must remove the chains, sprockets, chain covers, oil coole (maybe). Leave disassembled for your mechanic due to possibe damage to the pistons if reassembed with the cam in the wrong positon. Lock engine to make sure the crank does not move. For some reason I thought you couldn't get to the head allen bolts with the rockers in place.

[M491Cabriolet]

Thanks OldTee. I'm positive my pistons must be seized in the cylinders since the car was stupidly left outside for a period of time with the fuel intake removed. I'm sure water got in there. Since this is the case, is there any reason to lock the engine? I guess it's "self locked". Thanks.

[911 tweaks]

If I was you, I would buy one of those "c" battery powered bore scopes and stick the flexible camera eye end into any spark plug hole and have a look see. Cost about $60 for the el cheapo which is all you need... buy it online or evilbay.
IF you see any pockets in the tops of the pistons then you have a "tweaked" engine and worth potentially way more than a stk 2.4T.
Good luck!!
Bob
ps let us know what you find out and what you do to determine the inner guts specs, ect.

[M491Cabriolet]

Hi. Yeah, I think the only way to do this will be with a scope. I just spent some time to try to get it apart and without removing the cam sprocket, I don't think it will be possible to do it. The engine looks like when it was stopped for the last time, it was really in good condition. The chain is tight and there is no wear on the in ramps. The cylinders are not iron because a magnet won't stick to them. That (to my untrained eye) means it was upgraded from a T spec back in 1989 or so. I think the engine was worked on by the mechanic I bought it from, installing Carrera chain tensioners and SSIs, and possibly doing a rebuild and upgrade to a higher spec. The guy doesn't remember, unfortunately. Anyway, I'd say the work was so expensive the previous owner could not afford to pay for it, which is why it sat for 19 years and eventually ended up in my garage.

Questions: What do you mean when you say,, "IF you see any pockets in the tops of the pistons then you have a "tweaked" engine and worth potentially way more than a stk 2.4T."? What and where would these pockets be? Where are the numbers on cylinders? All I see is Mahle.

Thanks for all the help!

[911 tweaks]

1 or 2 "finger" shaped indentations in the tops of the pistons to allow the valves to extend further into the combustion chamber due to an aggressive cam used in the engine. These piston domes would speak volumes as to what the engine was then set up for and other mods would be required to make the engine a "whole pkg ~ proper build up" if built correctly.
Great to hear that the cyls are NOT magnetic = Mahle nikasil !!
Good luck here and buy a cheapo bore scope to answer the build riddle.
Bob

[dtw]

Just wanted to clarify Bob's info above regarding your cylinders. A non-magnetic cylinder, as tested externally, does NOT mean it is Nikasil. It may be Alusil or Nikasil but could also very well be Biral - aluminum core with a press-in iron liner (standard for 'E' and 'S' 84mm barrels). Depending on the magnet used, you may not have picked up the magnetism of the iron liner due to the width of the cooling fins.

Further - the interior of a Nikasil cylinder should indeed be slightly magnetic.

Not sure what finger-shaped indentations would look like, but circular or crescent-shaped indentations in the piston dome are valve relief. Here's a fairly aggressive piston - 2.2S:

http://www.pelicanparts.com/catalog/shopcart/911E/POR_911E_ENGpis_pg1.htm#

The aggressive wedge-shaped peak of the piston requires more relief for valve clearance. On the other hand, 2.4T pistons have very flat domes and require almost no valve relief. 2.7RS pistons are in fact quite flat-domed, as they are only 8.5:1 CR - they also have comparatively little valve relief cut into them, but a bit more than a 2.4T piston. Once you get inside, take some pics, we should be able to identify them easily. Another thing to check will be your bore size - whether it be 84mm or 90mm (or 92mm, now that would be interesting...).

[M491Cabriolet]

Well, I got the engine apart. I decided to cut the chains since I am sure these will be replaced. I then pulled the entire heads/cam housing assemblies off of the engine. I backed off on all the valves before doing that to prevent them from diging into the pistons. Two of the cylinders had deposits of junk (rusty water/sludge), but they all slid off with no problems. The pistons are Mahle 84P11, which are the 2.4 911S. version. I don't know what cams are in there. All I know is that the MFI drice is on the left cam. Any ideas how to find out what cams I have? So far, it looks good! Some serious money was put into this engine in the past. That explains the very good condition of the rest of the car to me. Thanks.

[notmytarga]

You would think that a mechanic that had a lein for the work would have the documentation handy or perhaps his lawyer has it. I'd ask again. Will the same mechanic be rebuilding it?

Enjoy the rebuild.

[M491Cabriolet]

Yeah. I tried to get information from him. He seems like the sort of person that won't do anything unless there is a big profit in it for him. He told me that the records are not available to me because they are from a long time ago and he does not want to search through many years worth of boxes for me. Oh well. I tried. He is no way on Earth going to rebuild this engine. He's up in Maryland anyway, so I am thinking of using a company more local to me in the DC Metro area. Now that I have it apart, I'm actually toying with the idea of sending the parts out for machine work and reassemling it myself. I think I am not capable of doing this myself, though.

[1982911SCTarga]

Those cam chains might have been perfectly usable. By all means, you should look into completing the disassembly/reassembly work yourself. Look at what you've already learned so far.

Brian