Headers for 77 911S

[Guardsred911]

I have a 77 with the 2.7 motor that had a Air injection pump on it no longer attached. The air injection manifold is still attached, and capped off. I'll remove the manifold and install the plugs.

It also has an aftermarket set of headers with heat exchangers i.e. not thermal reactors, but I'm looking to get either SSI's, or something similar for better performance.

In reading through the links and looking at the parts offered, it seems like there is a direct bolt on set of SSI's (although EXPENSIVE!).

Because I presume this had thermal reactors at one time, are there any issues with applicability? Asking as the heat exchangers offered by Pelican say "for versions without thermal-reactors..."

[75 911s]

The difference comes down to stud length. Thermal reactor cars had longer studs as well as a skinny middle section so the thick heavy thermals could be rocked into place on the stud. The studs are brittle and heat cycled. You will need to be careful when removing the existing headers. I broke 3 of 12 studs when I removed my exhaust off my 75. Given the original studs are a nightmare to change out in situ, people buy the thicker SSI flange for cars that had thick flange thermal reactors originally.

You can use either the thin or thick SSI. If you use the thin, you need spacers, because the only nut that fits through the SSI in 3 specific places are the special allen head cylinder nuts. When the nut goes too far onto the stud, the stud protrudes into the drive area of the cylinder, making the allen driver slip or not have enough depth to drive the nut anymore. Copper nuts are best on the other easy access stud points.

I soaked my studs in PB blaster or kroil. A few days. Then I used a technique to quickly pop the nut to try to break it free without a slow twist, which was much more likely to twist the fragile bolt in half. Again I was successful in doing this on 9 of the studs. 3 of them the nut was fused and it twisted the stud off in the middle. In retrospect, I may have tried to heat the nut cherry red as many recommend here. You can then back them off the stud easier. The problem with heat is that you might fry the cooling tin that resides between the cylinders. Bubble up the paint there etc. A pen torch might be best.

If you break a stud, the stomski kit is avail to center drill it out perfectly. If you try to do it by hand you can damage the cylinder and then a new stud will never sit right in there. Ask me how I know. (I did buy the kit after all)

SSI looks and performs great. Worth the money. If you are patient, they appear on the classifieds about every 6 weeks.

The vents that stick out of the heat risers are for MFI cars. You want the thin or thick flange SSI with no other heat vents.

[LUFTKUL]

It sounds like your exhaust has been changed once so hopefully prior owner used anti-seize on the studs. SSIs are a worthy upgrade.

I broke 2 studs off my '77 stock exhaust going to SSIs. I bought the Stomski kit and drilled them out successfully from under the car with jack stands. It was not a pleasant experience, but I got it done. Definitely wear sealed goggles if you drill like I did. You do not want bits of metal in your eye.

[Guardsred911]

That's great detail, Thank you! I put SSI's on my '80 SC, and love it... I definitely hope to do the same here....

I'll report back as I get going on this... I am also hoping the previous owner did some good R&R on the studs!

[Targalid]

When I removed the thermal reactors I used a torch, heating each nut cherry red before giving it a quarter turn On cooling each nut easily was removed. No studs were damaged.