Drilled exhaust stud - did I go too far?

[jedoyle]

Hi everyone,

Looking to get some advice regarding an exhaust stud that snapped while converting to SSIs on my 1983 911SC. After the stud snapped I bought the Stomski kit to drill it out. Unfortunately, while drilling with the 3/16” bit I believe I drilled too far. I compared a stud hole with the stud removed to the hole I drilled and found that the hole I drilled was about 15mm longer. I did a better job with the 17/64” bit and drilled it to almost the exact same length as the empty stud hole. But what did I drill into with the 3/16” bit? Is my engine damaged? Pics below for reference.

[75 911s]

In my opinion you are fine. I've seen drilling beyond that point and it usually just hits a fin and not the all important head chamber where combustion takes place. You should be good. I would test with a new exhaust stud and see if it's level with the existing studs - at least when you go to tap out the new hole.

[PeteKz]

Concur with 75 911s. If you pour liquid into the hole, and it doesn't drain out, you did not go too far.

[slow&rusty]

You should be fine.

You're not the first this happened to.

[jedoyle]

Thanks guys! I was about to have a heart attack!