I've searched and found that the exhaust manifold studs/bolts are 10mmx1.25 and you can use 50MM ~ 60MM in length to try and catch the extra threads in the hole......but what grade bolt should I use? Grade 5 or grade 8? (metric equivalent of course)

Thanks.

 

Five is plenty. It's not structural, just holding the parts in place.

 

What ever is cheapest. The head is aluminum, so its not torques too high anyways. Also, make sure to use a stud and nut, not a bolt, again, as it aluminum which strips easily.

 

Ain't that the truth. I have two helicoils for my manifold already.

There are two bolts, btw. But, they're only for the manifold plates. Otherwise, I concur...use studs. 4t for non-grooved.....6t for grooved. The groove will be on the end of the stud, if there are any.

Edit: I'm pretty sure it's 4t on the exhaust. 6t would have be for wheels studs.

 

I always use new Toyota studs and nuts for trouble free operation.