Yep!
I had some pinhole leaks following a repair on one of my heads. The leak was opposite the valve spring seat where the runner gets very thin. I couldn't pull up the pdf file (long story) so I'm not sure which LockTite was being used to make the repair. However, I used some LockTite that Marc recommended, applied vacuum to the runner to draw the goop in until I could see little beads of the stuff coming through the pinholes. I let it cure 24 hours and re-applied the vacuum and tested for leaks with soapy water. NO leaks.
That was a couple seasons ago, and upon inspection last fall, still no leaks.
Bob G tried to use the same stuff, but for some reason couldn't get it to set set up. (Bad batch or something???) It never would harden - just remained liquid even over night
. So, he ended up using some type of aviation-grade aluminum-impregnated epoxy and massaged it into the pores and then sanded the runner smooth. Seems to have done the job!
P.