Going through my block on my VVT motor before bolting the oil pan on and noticed two of the ARP main studs seem to be sitting lower than the others (two closest to the camera in attached photo). I assembled everything according to ARP's directions. Finger tight on the studs, lube on all the interfaces, 60lb/ft on the nuts in three stages. Used a fancy pants Snap-on torque wrench so the torque measurements should have all been consistent. Are two of the studs shorter than the others and supposed to be situated in one of the mains specifically? I made sure all the bores were clean before installing and I don't remember any of the studs being shorter than the others but this has be second guessing myself. Help/suggestions anyone?

 

I now realize how stupid that question was. I removed all the nuts, main caps, and studs. Obviously all the studs were the same length. Gave each of the bores another cleaning with a brush and some brake cleaner and compressed air. Looked inside each of the female threads with a light, doesn't look like there's any other debris in there. Finger tightened studs again and followed the torqueing procedure. Studs all sit at the same height still. At this point, I'm assuming a couple of the female threads in the block were drilled to different depths.

 

There could be a lot at play. If it really bothers you, pull the studs out and measure them. My money is on the tolerance on the depth of the bore into the block being pretty loose hole to hole.
Mazda used bolts for this application so there would need to be some clearance below the bolt.

 

That's about what I figured. I cant imagine overdrilling those holes by a few millimeters makes enough difference in block strength for the manufacturer to care. Could've grabbed a depth gauge to really get scientific with it but everything is back together now and my mind is at ease. Now onto the next questionable thing I find while putting this motor together.

 

I've run into the same issue on my VVT Miata build. Did everything turn out okay with your engine build?
There are a few bolts like this, all are on the same side of the engine.

 

Yep! No problems yet since then. If you want to go super deep in it, you can grab a depth gauge and measure the bores.

 

I didn't realize the dates on the original post. I was so confused why Z had pulled his engine back out.

 

Pulled the engine out to make sure it wasn't part of the driveline vibration, ya feel?