needing new exhaust manifold bolts 1987

[weider1717]

I am looking online for correct "double circle" headmark bolts.

Also i can't tell if they're 9/16 or 14mm. Anyone know? 14mm fits more snug but I was thinking they was 9/16?

which is correct and where in the world can I find a new set I have looked all over.

1987 v10

thanks for any advice guys

[95 S_Trucker]

They are 3/8 bolts, with a 9/16 head. Most just go to the hardware store and get bolts with a washer. You can try gm. Sometimes they still have bolts around.

[weider1717]

you guys sure they aren't 14mm it seems to fit a tiny bit more snug 9/16 seems loose.

If they are intact 3/8 x 18 with 9/16 head I think I found some online.

[4x4k30]

Originally Posted by weider1717

you guys sure they aren't 14mm it seems to fit a tiny bit more snug 9/16 seems loose.

If they are intact 3/8 x 18 with 9/16 head I think I found some online.

I am not postive but the best way to tell if they are metric or not is to use a 15mm wrench or socket if the 15mm fits its a 14mm metric stud or bolt if it takes a 9/16th wrench its the standard 3/8ths

[KrazyRay]

I have parted many trucks and I have never come across 14mm hex heads on any bolts. GM used 10, 13, 15, 18, and 21mm nuts and bolts when they went metric. All 87 manifolds I have unbolted were 9/16". Japanese metrics are 10, 12, 14, 17, and 19mm.

[old Rusty C10]

I recently wanted OEM style bolts for my 350 motor on my 71 monte carlo and found them on Ebay