Flywheel bolts what size socket ?

[Hoofa]

Gents just replacing helix clutch which didn't make 2000 miles, I need to get the flywheel bolts off, they look like a 12 point socket head bolts, anyone know what size they are as I need to get a socket ?

[v8 racing]

19mm i believe

[vaurien]

UNF 7/16 x 1

[spend]

12pt sound like ARP bolts, they require a 12pt 5/8"AF socket IIRC.

19mm is used as a nice tight fit on the 3/4"AF std hex headed bolts I believe?