[JEC3039]

Formulas - I secured the manifolds before seeing your note so too late to check the hole diameters for now. Next time manifolds are off the car I'll try to remember to report back...

[64-3Deuces]

Originally Posted by JEC3039

Formulas - I secured the manifolds before seeing your note so too late to check the hole diameters for now. Next time manifolds are off the car I'll try to remember to report back...

On cast iron manifolds the outer holes are larger to account for expansion and contraction (thermal cycling). I researched this when I noticed the larger outer holes on my ram air manifolds. There is a thread or two about this subject on this forum.