Engine Rebuild Advise

[dwiniger]

I am starting with a early '68 911 T Engine. 2.0L Aluminum case, with the CB Crank. I would like to keep the original case, crank & rods. (& heads if possible). I don't want to cash out the 401k to build an engine....

Maybe go with new Mahle 2.2L P&C's.

Can I use my original heads and have them machined with this combination? Would I need new cams, or could mine be reground?

I am looking for good street performance, not track racing. The engine will be going into a 1966 '911 chassis.

[NICE 69 S]

This topic has been discussed quite a bit on the Early S Forum. Many years ago I put 2.2S pistons in my 1969 2.0S. The engine was never started and has sat in the car for 25 years. When I started to get interested in putting the car back on the road, I started reading a lot on the Registry. The general consensus was that this engine would have about 7.5:1 compression, down from 9.8:1 of the original motor. If you can find pictures of the 2.0 piston vs. the 2.2, you will see why. When Porsche went to the 2.2, the profile of the piston head was flattened, and the head has a much shallower combustion chamber.
If you want to go to an 84mm piston, you can probably get a custom set from JE that will work with the early high dome combustion chamber. Otherwise, you will be way down on compression and HP with a stock set of Mahle 2.2 cylinders. Also, with the 2.2 pistons, you must machine the old heads for the 2.2 style head gasket.
In my case, I purchased a set of 2.2/2.4 S heads that match up with the 2.2S pistons, and hopefully pick up about 10 HP over the 2.0S.
Bob B

[NICE 69 S]

If you can post your engine build number (901/xx), located on the right side of the block just under the fan, I can tell you what size valves are in the heads (if they are original to the motor).
In 1968, all the heads except the S had 32/32 port size, but some had 39/35 valves and some had 42/38. Obviously if you are going for larger displacement, the bigger valve size would produce a better outcome.
All of this info is contained in Appendix A of Waynes "How to Rebuild...." book.
Bob B

[dwiniger]

I have the following:

901/13
10359
2180031

I am certain the heads are original.

I guess I would like to stick with the Heads I have.

My next question would be, If got the Mahle 2.0S pistons, would I be able to modify the heads to get an "E" type drive ability? What would be involved with that? Would I need new cams? Based on the head valve dimensions, what valves would have to be replaced? Head work cost?

I appreciate you sharing your knowledge.

Just trying to get an old T to run like a new E.....

[NICE 69 S]

901/13 engine gives you the same valve size as the "S" that year (42/38), just not the compression or port size.
What you have here is exactly the same port and valve size as a 1969 "E", but a 69 E had 9.1:1 compression (+ better cams and MFI), and your 68 T motor has 8.6:1.
I am not an engine builder, so maybe someone else can chime in about build specs, but you may want to check with JE and see what piston/cylinder combos they have to get you a little more displacement and something closer to the 9.1:1 compression of the 69E.
Nice set of 82.5mm JE 9.5:1 pistons and cylinders here for a good price. 82.5mm Porsche 911 JE Forged Piston & Cylinder kit for 2.0 | AA Performance Products This combo will give you 2117cc.
Bob B