Jeff: One of the above posts is incorrect - NO SCs were fitted with thermal reactors. All have catalytic converters; the '78/79 cars also have a smog pump. Another poster stated that most 3.0 engines need top end work at about 100K miles. Not true, the valve trains in these engines are extremely reliable, often lasting more than 200K miles (my '82 is now at 203K miles, uses the ideal one quart/1,000 miles, run on Kendall GT1 20/50). Of course, if a car is abused (driven very hard with a cold engine, using lousy oil, etc.) all bets are off. Top end issues do exist, often the problems are broken head studs and updating to Carrera timing chain tensioners. Neither repair constitutes an upper rebuild, each is simply a necessary repair. A solid PPI technician can help you get through any problems a particular car might have, then you must choose to walk away or dive in.
Pete

 

I think the one poster confused the SC with the Carrerra's. From what i have read the Carrerras can have vavle guide issues by 100k, but if you avoid a broken headstud in an SC (unfortunately I did not!!) and change the oil at regular intervals you can get over 200,000 before a rebuild.

 

Peter, were ALL 78SC's standard with smog pumps or just CA cars? I know mine is "pumpless", most likely removed long ago but i'm curious if it was ever there to begin with. It would add, I assume, a bunch of possible plugs that need to be maintained (like on my old TR6)..

 

One other consideration is the 78-79 had the lower compression pistons, but bigger-valve head and larger intake runners, while the 80-83 had the higher compression pistons with smaller-valve heads/runners. No net gain in HP, but purportedly better midrange grunt from the latter, from what I've "heard" FWIW.

Edward

 

Thanks again to everyone who has contributed. I have much to think about now before my next purchase as to which SC I will go after.

Edward, do you know if there would be a benefit of using the older heads on a newer car to let it breath a little more? Thanks,

Jeff

 

Hi Jeff,

That idea has been kicked around for some time, and to my recollection I don't recall anyone stating definitively, and with dyno results to corroborate, that such a combo would yield demonstable gains in HP. More significant, and this has been demonstated time and time again, simpler improvements in the breathing characteristics of the 3litre improves HP and throttle response significantly. Both incarnations of SCs benefit significantly from SSIs (i.e. early-style heat exchangers), more open muffler (does not need to be deafening), and cams ...and this even with the stock CIS injection. These mods are not only less expensive than getting into the heads, but they have been "proven" by experience and repeated over many an SC ...mine own included
Hope this helps

Edward

 

Dave-
A feline-damaged SC is no good for you. Its a tough thing to take on, but I'd be willing to buy from you in its molested state

Kurt

 

Gary: Yes, your car was born with a smog pump. Check the rear engine sheet metal shroud, you probably have a hole in it, near the left, outboard engine mount, where the plumbing used to pass through. Because it's been removed no maintenance items remain. The only issue are the exhaust ports, either the air injectors were removed and replaced with small plugs, or they were left in place and capped. If they were capped, if the system is ever restored those injectors will have to be replaced because they plug solid with carbon.

General clarification: All SCs have 49mm intake valves, and 41.5mm exhaust valves. The '78/79 cars have an intake port that's 5mm larger (39mm vs 34mm), but the exhaust ports on all SCs is the same (35mm). The early cars use larger diameter intake runners, but the '80-83 cars have a solid improvement in torque with the smaller runners and intake ports. All USA SCs are rated at the same HP (180 DIN). If a camshaft change is done care must be taken to not disrupt intake manifold vacuum. CIS injection depends on that vacuum to operate properly, which is why Porsche was so conservative with cam profiles for the CIS cars. Although all SC cams are similar, the late engines have a different timing spec, which must also be taken into account. Regarding compression, '80-83 cars have higher compression (9.3:1 vs 8.5:1), made possible by the more precise CIS which includes Lambda (oxy sensor, ECU, etc.). I've found, after years of fooling with SCs, that combinations of parts (heads, airboxes, etc.) isn't nearly as important as; 1) camshaft timing is crucial, and should be done to .001mm side to side. 2) piston and cylinder sets, when replaced, should always be replaced with Nikasil (many SCs were originally built with Alusil) units. If those two items are done, and all other assembly procedures are correct, the engine will feel alive!

FYI: Yes, many 3.2 Carreras have required valve guide replacement at or near 100K miles. I've seen some reach 130K miles, but by that time they're usually consuming a quart in something less than 500 miles. Our recommendation was to fix it when consumption deteriorated to 300 miles/qt.
Pete

 

I have nothing to contribute other than a picture worth a thousand words...........
82 SC

 

Hmmm, valves are the same, just the intake runners are different. Thanks, Peter, for clearing that up! I certainly don't want to spread misinformation. As been said many times before, you are a true asset to this board!


Edward

 

Pete must be right, & I must have recalled a friend's pre-SC CA 911 that had thermal reactors as an SC. Leffingwell's Buyer's Guide also lists the '78 & '79 CA SCs as having thermals. My apologies.

 

Glad to help, you guys are great! No apology necessary, these cars are getting pretty old, which is certainly going to contribute to the info glitch factor. I'm just amazed, every time that I drive my '82, at what a good car it is. 200K + miles, and 24 years old - simply amazing.
Pete

 

Thanks, Peter. And on your latter note (and not necessarily off topic) my 82SC is also an amazing car considering its age. I don't remember any car that was this quick, handled this well, or made me feel so good back in the 80s. And by today's banchmarks, it still is a stellar car. 911s are simply amazing cars, with each variant simply a different flavor. Merry Christmas, all! And good luck to you, Jeff, in your hunt!


Edward

 

Pete and Ed and all 82" Sc Owners... We should start a poll to see how many of us we have here. Mine is amazing too.