The front exhaust manifold bolt on driver side is missing on my 1990
460 EFI Ford.
What size replacement bolt do I need.

 

FAL, Is the bolt missing or is it broken off in the head? The bolt is a 3/8" coarse thread. The length could vary. I am thinking around 1 1/2" - 1 3/4" long. The best way to tell whats up is to take a small screwdriver or a stiff piece of wire and stick it in the hole and see how deep the hole is. Bottom out in the hole what ever you use to measure the depth then subtract another 1/4". If the screwdriver does not go in very deep, only the thickness of the exhaust manifold or close, the bolt is broken off.