340 CAST IRON MANIFOLD BOLTS......WHAT THREAD ?

[cudaneil]

HELLO GUYS,
                   One of my exhaust manifold bolts fell out, and i need to know what thread they are to get a new one !

      So are they  unf......unc.......metric(dont think so)    I think the size is  3/8     


                                            Cudaneil      

[Changin Gears]

Small blocks are 5/16-18 thread

[72hemi]

  Small blocks are 5/16-18. the big blocks were 3/8.

[cudaneil]

   Thanks Guys,
                       Been having a closer look, and these are definitely 3/8, and they are all bolts !
 
                        They were originally 5/16 studs.............somebody must have upgraded them.

                       And the bolt hasnt fallen out  its  SHEARED OFF   

                          TIME TO GET OUT THE DRILL      

                        just to make matters worse,its the rear one(the one that goes into the water jacket) 

[cudaneil]

   Managed to repair it !...............Dropped the manifold out of the way,got my mini pistol drill in there with a 6.5 mm bit.

         Tapped out an 8mm thread in there, put in a metric bolt with thread sealer.  New manifold gasket . 

                                      Sorted !!!         

[Chryco Psycho]