Swapping out a 3.0 for a 3.2
 

I am looking at pulling the trigger on my first 911! Question for you experienced lads. would anyone have any concerns about purchasing a 79 SC that had received switch over to an 84' 3.2 done by a reputable shop? Tranny has also been rebuilt but I'm wondering if that raises a red flag for anyone in terms of compatibility? Does anyone else have an SC with 3.2? The Carrera engine has 90K on it.

No issues.
Unless you live in a strict emissions state and the car is not emissions legal with the swap.
Otherwise the swap is a nice upgrade.

Unless your looking for a numbers matching car I don't know anyone who would chose a 3 liter CIS over the 3.2 motronic.

agree with Derrick -- however, if a 3.2 is going to develop premature valve guide wear/excessive oil consumption issues, 90k miles is about the time it's generally going to show up (and require a top end rebuild to address)

Thanks All! Derrick, thanks for that info. These concerns can be checked out with a compression and a leak down correct?

My top end on my 3.2 was at 160,000. I think they will last a bit longer than 90k if you talk to most owner’s with a 3.2. Motronic Engine is much better than a 3.0.

The 3.2 valve guide issue seems to be limited to the '86-'87 or '88 engines. A compression/leakdown test couldn't hurt, though.

Agree that the 3.2 is a Great engine -- but don't necessarily agree that 90k is too soon to need a top end. My '86 needed one at 70k, as it was consuming around a quart of oil per tank of fuel.

Had not previously heard the point Graham mentioned above, if limited to engines built from 86-88, then likely NOT an issue in an engine from an '84 :)

Also, since the worn valve guides allow oil to seep past the valve stem, worn valve guides won't necessarily manifest during a leak down/compression test, which is performed with valves closed.

At a minimum, the 3.2 premature valve guide issue is something to have a mechanic familiar with our air-cooled engines look for during a PPI.

Nikasil was also used in our 3.2 cylinders. My mechanic who did my top end said this was a real plus for engine life.

Some 3.2 engines came with really soft valve guides. Some came with great valve guides. My 85 3.2 came with valve guides that were worm at 150,000 but the engine was apart for other issues. Of course we did new guides "while we were in there" along with some other fixes.