I have a complete J13 out in the garage on a dolly, so let me check.
I think Conner mentioned in a previous post that a cap from a Fairlady roadster works, so let's see if he chimes in.
Be right back.
Okay the answer to your "loaded question" is not exactly
. That is, do you have a two bolt valve cover or a 6 x screw valve cover? If a 2 x bolt - NO a cap from a J13/520 or one from a Fairlady Roadster will not work. If you have a 6 x screw valve cover then YES, your are in luck. A J13/520 or Fairlady roadster will work. If you have the 2 x bolt, I'm stopping by Victoria British this Friday and can size up a cap from a Sprite/Midget or MGA/B and confirm fitment for you. I'm stopping by for some interior door panel parts - so no issues. Give me a few and I'll upload some pics....
Andy