need to run to the hardware store; i was thinking about grounding at the front or back of the passenger side head. would anyone happen to know what size bolt i need? for some reason i think it's metric, maybe M11 x 2.0 but I'm not sure:



thx

 

Pretty sure that it's M10 x 1.5 (going from memory there)...

 

Yes, those are all M10x1.5.

 

I like the flanged headed metric bolts. A good source is mcmaster-carr(mcmaster .com). Depending on length <$10/25. Pt# 98093A619.These are good quality metric Grade/Class 10.9 which I believe is the equilavent of SAE grade 9 bolt.
I also like to drill and tap the above bolts and insert #10-32 stud. Add a insulated band clamp and locking nut as shown. Very helpful for securing wiring harness across back of engine head/block.

 

Here is a list of all the threaded holes in the OE LSx heads;

Spark plug 14x1.25mm
Coolant temp port 12x1.5mm
Ancillary/accy holes 10x1.5mm
Exhaust manifold 8x1.25
Rocker arm mounting bosses 8x1.25mm
Intake manifold 6x1.0mm
Valve cover hold down 6x1.0mm
Steam tube hold down 6x1.0mm