GothingNC

I am going to be looking at a low mileage 77 911S coupe tomorrow
Engine has had stud inserts installed at 40,000 miles.
The shop reinstalled the Thermal Reactors because the owner is a stickler for originality .
Head studs were checked at 70,000 miles and they were fine
It now has 73,000 miles.

Will a 74 or earlier exhaust set-up bolt in or is there a way to just replace the Thermal Reactors beacause the orginal exhaust & heat exchangers are just fine.

Thanks !

John

DGaunt

Yep back-date to 1974, preferrably in SSI staijnless w/heat exchangers, if you need heat.

External oil cooler? You may have to change a line or two at the engine end.

911S3.6

Hi John,
As an owner of a 1975 911S, I respectfully suggest you get rid of the thermal reactors-preferably by replacing the whole exhaust with an 1974 style set up (SSI's would be the best investment). Note: the 74 set up had equal length header pipes on both sides which proved to be a cleaner running and more balanced set up for engine performance. The 1975+ smogged cars had a wrap around system that even without the reactors is a compromise. Also, the Carrera chain tensioner update, an external oil cooler in the front right wing, and a pop off valve on your airbox will do much for a long and happy living 911, especially if you plan on driving the car.
Nick

GothingNC

I have not made a decision about the car.

After doing some readings about TR heat, I am nervous about the case strength being compromised by the TR's and valve guide damage even though head stud inserts have been installed since they have been on the motor for 73,000 miles.

The big question is if it will make it to 100,000 before it starts leaking like a sponge??

My brother used to have a 77 Targa. the head studs never pulled but at 110,000 miles it was leaking all over the place even though he had the reactors removed at 20,000 miles, fan upgraded, front mounted oil cooler etc.
Car was not worth the engine rebuild at the time. He likes the 2.7 motors but not the ones that have had TR's installed.


John

Edgy01

Two thing really complicated life for the 911S engines in 1977. First, the magnesium cases had a thermal expansion contraction issue (always pulling head studs) and second, the thermal reactors introduced MORE heat than needed in the worst place,--on the bottom of the engine,--and that heat would rise up toward the case. This was a total screw up in Porsche engineering.

There's no way I would EVER buy a 1977 911 again.

dan