Inlet manifold bolts

[sssammm]

Just bought some S/S ARP 12 point bolts 1/4 x 20 for my inlet manifold, what socket size to they take?

8mm too small 9mm too big, 5/16 too small, 11/32 seems to fit but not exact, a little wobbly.

Any Ideas here?

 

[Nader]

I have them if you are interested. I ordered way too many.

 

[ROCKET62]

Are the bolt heads a "reverse torx" or an "E-socket" as it seems to me that I had to buy a special set of sockets to remove the bolts??