A groove has to be machined to take the sealing ring. There are also other changes ... eg they changed the material used in the O ring sealing the bottom of the barrel with the crankcase as the earlier ones become britle and leak.
There is no difference between an early engine or a late engine as to when they will need a top end overhall.
The early engine is prone to cylinder heads blowing and some additional oil leaks which is not related to wear in the engine. Oil leaks can be lived with until a top end overhall is required. If it gets bad you need to take the engine apart and reseal it to cure which with labour rates usuall comes to about £2000. Whilst in there it's usually worth having the heads machined and actually doing a top end overhall.
If you are looking at any 964 you should get a professional opinion of the engine regarding leaks and general condition. That way you'll know when a top end is likely to be required. Compression test, leak down test and visual inspection for leaks is the only way to get a true picture of the engine (applies to any 911 IMO).
BTW my car is an early engine and has an oil leak. It's done 90K and engine is still in very good condition. Plan to rebuild engine at 120K (top and bottom) and then it will be good for another 120K. I will live with the oil leak for the next 30K miles, it's just so not a big deal.
Ian.
There is no difference between an early engine or a late engine as to when they will need a top end overhall.
The early engine is prone to cylinder heads blowing and some additional oil leaks which is not related to wear in the engine. Oil leaks can be lived with until a top end overhall is required. If it gets bad you need to take the engine apart and reseal it to cure which with labour rates usuall comes to about £2000. Whilst in there it's usually worth having the heads machined and actually doing a top end overhall.
If you are looking at any 964 you should get a professional opinion of the engine regarding leaks and general condition. That way you'll know when a top end is likely to be required. Compression test, leak down test and visual inspection for leaks is the only way to get a true picture of the engine (applies to any 911 IMO).
BTW my car is an early engine and has an oil leak. It's done 90K and engine is still in very good condition. Plan to rebuild engine at 120K (top and bottom) and then it will be good for another 120K. I will live with the oil leak for the next 30K miles, it's just so not a big deal.
Ian.
