Changing exhaust,what to expect ?

[B85]

I have a 1979 911SC and I'm looking into backdating the exhaust system. What should I be ready for ? What problems are usual ? Studs,bolts, things that brake.

Also is their a BEST system to look at ? Would like to keep the heat. (don't know why I like in Phoenix) maybe I don't need it ?

Thanks for the ideas and input.

,Randy

[McLaren-TAG]

Search for keywords like backdating, heat, 3.0 exhaust, sound, 2 in 1 out, SSi and you'll get about three days worth of reading materials and more opinions than you'll know what to do with. You may even still be confused or a bit unsure of where to go from there but you'll be a hell of a lot more knowledgeable about the options you've got in the budget you should set for yourself.

[B85]

Thanks Mc.
It was more what will brake off during the replacement !
Randy

[tobluforu]

Lots of threads, start spraying the heck out of the nuts with Kroil, etc. This is not a cheap adventure, ssi's are expensive, and if you want a plug and play muffler, that will cost ya as well. 2g's, give or take.

[Oh Haha]

+1 to doing a search.

There are a lot of variables to which exhaust to use. Sound is obviously selective.

Do some reading before deciding and you won't regret it.

[scarceller]

You may have issues removing the nuts and studs at the heads that bolt the exchangers in place. I'd use a 50/50 mix of acetone with trany fluid and start applying this to the nuts days ahead of time. You don't want to snap a stud as it will break flush at the head! If they don't come off don't apply more force you will snap the stud. A trick I use for a nut that won't come loose is to mig or tig weld right on top of the nut, the heat seems to instantly loosen the stud from the head and then the entire stud comes out easily with the nut welded on top. Of course you'll need a replacement stud and nut after this procedure.

[gtc]

Exhaust studs are the biggest concern.
The most sure fire method I've found to remove the heat exchanger barrel nuts is to heat the nut until it's glowing red hot with a torch (acetylene works well), wait a few seconds for it to cool slightly, then try to unscrew. That seems to be the best way to break the rusty nuts free from the studs.
Kroil, PB blaster, or whatever magical penetrating oil concoction you have faith in, only sorta-kinda helps with this.

[vesnyder]

I did the backdating last year and went with the SSI's along with the M&K exhaust ('83 SC Cab). I had the engine off of the car when I did it but the broken studs are your biggest concern. A bit pricey but well worth the investment.

[scarceller]

I have a 3.2L Euro with SSIs and M&K 2in2out pipe, I then had M&K deliver the pipe with a cap for one side and this turns the pipe into a basic 2in1out. If you go with a 2 out pipe be aware that most drone and some real bad below 3000RPMs. When I cap one side the drone is completely gone but I also like it uncapped at times.

[B85]

I have read some of the installs here and needed a heads up about the studs.

Looks like my $2000 will just about get me their ? May need to fab my own muffler ?

What about going with a header . Our max cold is about 30 to 40 mornings in the winter then 60 to 70 during the day. And in day light the inside can just get hot in the winter. Ideas ?

Have you found if you have some new exhaust studs on hand they just come out ? LOL Just a idea. With me if I have "it" I never use it.

Randy

[scarceller]

Use the SSIs in a 3.0L anything bigger than 1 1/2" won't work well on the 3.0L you need to keep the exhaust velocity up to help with low end torque. I don't recommend 1 3/4" or 1 5/8" headers on the 3.0L

[B85]

I think you are right after reading some reports on the 3.0l and big pipes.

Anybody in Phoenix running a 911 with just a header and muffler ? Is it working for you ?
Randy

[Josh D]

I would also caution the oil line removal at the external oil thermostat when you backdate the oil lines. I cut relief slots in the nut with a cut off wheel so the nut wouldn't take the aluminum threads of the thermostat with it.

I'm in AZ and I stuck with early heat exchangers and kept heat as mines a daily driver and we do have mornings around freezing in the winter as well as rain occasionally that requires windsheild defogging.

[B85]

OMG you drive in the rain ? LOL Isn't that a no-no ? Just kidding.

Thanks for the nut pointer.
Randy

[LUFTKUL]

I'm over $500 in tools trying to get one snapped exhaust stud out and I still don't have it corrected yet. Kind of been one nightmare after another. Kroil, map gas, you name it, I tried it.

The oil line replacement was easy compared to these stupid exhaust studs. Not to mention I ordered the wrong SSI model...

[B85]

That's what has me asking, Luftkul

Just trying to be ready, that is if you can be ready ?

[JJ 911SC]

What model do you have, Cab/Targa/Coupe?

I put a 2in/2out (M&K and Dansk Sport) on my Cab. No problem but I don't think I could have live with it in a Coupe.

I though this would have been popular : Muffler Loan Program

[B85]

Its a Coupe ,JJ. I have a flowmaster on it 1 in from the cat ( which will come out ) 2 out and its a little loud.

[JJ 911SC]

Originally Posted by B85

Its a Coupe ,JJ. I have a flowmaster on it 1 in from the cat ( which will come out ) 2 out and its a little loud.

If you backdate, it would be either 2in/2out, 2in/2out with a cap/valve on one of the pipe (on demand) or 2 in/1out. Even before my backdate, I had a 1in/2out so there was no way I was loosing a pipe

Like I mentioned, in my Loan Thread, the best would be if you could borrow some set up and try it.

See what local Pelicans can help you with.