Differences for a California engine?

[DUK]

Engine# 6561618 in my 75 911. According to Wayne's book it's a 76 California engine. What should I look for and what should be changed if anything? BTW it's already been molested by MM. And now #5 has no compression. Not quite ready to tear into it, but it's getting closer everyday. Thanx, Duke

[Jim Sims]

Depends on it's state; does it have thermal reactors? Does it have any pulled head studs?
Most normal engine rebuild procedures apply: inspect and measure everything and repair or replace if damaged or out of tolerance. If your emissions inspection rules permit, the thermal reactors should come off and be replaced with three to ones or even better with SSI's or early style heater boxes but this addition will require removal of the lower air injection and EGR systems.
Valve guides should be replaced with the better silicon bronze type. If a head job is being done, have the machine shop change out the "necked down" exhaust studs (head to to thermal reactor or heater box joints). Pressure fed chain tensioners should be added. If there are pulled head studs or you're pulling the case apart then significant checking and machine work will likely be indicated. The case will likely need to be squared, bored and thread inserts (case savers) added (don't forget the 8 mm stud inside). New Dilivar studs.

Other helpful upgrades: 5 to 11 blade fan, external oil cooler, modifications to cylinder baffle sheet metal.

[Henry Schmidt]

In California the best replacement for nuclear sorry thermal reactors is to retrofit a catalytic converter from an SC. It requires changing the, heater boxes, muffler and one oil line but it cleans up the exhaust, lowers operating temperatures and most smog guys don't know the difference. If smog is not an issue, ***** can the exhaust and install SSIs.
There are 4 8mm studs inside the case that should be inserted and I wouldn't use Delivar studs in a law mower.
Delivar studs are a bad idea in every engine and should be stricken from the Porsche vocabulary.

[Jim Sims]

The thermal expansion coefficient difference between steel and aluminum/magnesium remains. Dilivar is one solution; the other being higher strength alloys for the studs combined with thread inserts in the case to brute force (strength) a solution. Dilivar has to be protected from corrosion; the new studs come with a different coating compared with the originals. The Dilivars in my '76 2.7 engine are hanging in there but they were carefully re-coated when the engine was apart to address the generic 2.7 engine weaknesses.

When replacing broken Dilivar studs without a bottom end rebuild then using the newer Dilivar studs is a reasonable repair; merely substuting steel studs runs the risk of converting a broken stud into a pulled stud.

[DUK]

Thanx for the reply guys. The thermal reactors have already been eliminated and I'm planning on SSI's. As far as everything else I'm just waiting to get the tub done and then focus on the engine.