like to know if anyone did use JB weld in the intake port . im trying to fill out the injector hole in my 4781 L36 head those are the same casting as L67 heads whit the difference that the injector hole are not drill but there a hole in the intake port that not good for flow

I would think that you could use it as it'* designed for the temps and elements involved. However getting it welded closed and smoothed would be a better solution in my mind.

I investigated attaching some sort of device in the LIM in the past, and through my research and asking alot of questions, discovered the preferred goop is a marine-grade epoxy similar to JB weld, but with known petroleum fuel resistance.

on the JB weld site they say its good 500 degrees and once hard gasoline wont affect it

Don,

Your idea seems iffy to me. I think you run a real risk of the epoxy "plug" (or pieces of it) falling out and getting sucked into your intake valve (or combustion chamber).

The area you want to fill is rather smooth, and kind of "cone" shaped with the large end of the cone pointing into the runner...in other words, there'* really nothing i see that will securely hold that cured epoxy "plug" in place. Also, with thermal expansion of the cast iron, I foresee the epoxy plug actively wedging itself out.

If you must do this, you might consider high-temp RTV...it is less likely to wedge or "pop" out, and far less likely to destroy a valve or piston if it does fall out.

Best of all would be to find a set of those 8134 heads without the injector pockets and use them for project heads...

Yeah that could be bad, if one fell out.

Alternately, you could perhaps machine some undercuts into those smooth holes, for the epoxy to mechanically grip against. Even if the adhesion failed, the plug would remain in place unless it broke apart somehow.