With the bearings out of the way, its time to finish prepping the block for assembly.
First thing was to run an 800 grit dingleball hone in the mains for a few seconds to clean up some of the less than ideal surface finish, and chamfer the other sharp edges around the crank. This gives the bearings more surface area to support them and transfer heat away from the crank, and gently deburs the sharp edges in the main tunnel, reducing stress risers and making the block generally easier to work on since there's no sharp edges anywhere to catch and drag on stuff. The material removal during this process was effectively zero, maybe 0.0001" at most, but the surfaces are much nicer.
Before (the scuffs are from bore gauges)
After:
Then come the Timeserts for the head studs, the threads in this block are fine but I'd prefer to have something a little more future proof. I ended up just buying a kit on Ebay a few months ago since the machinist I rented it from for my first block back in 2019 is sadly living happily retired in the mountains somewhere in New Mexico.
My previous experience with timeserts resulted in them all being slightly crooked, as far as I can tell this is normal and doesn't hurt anything but it bothered me. So for block #2, I paid a machine shop to do them....and they still ended up crooked. So I decided to make my own method that results in nearly perfectly straight and true thread inserts.
First off, the alignment pin to line the drill plate (plate you bolt to the block to hold the drill bit steady) up with each hole. The NSX head bolt holes are larger than the studs and fairly deep, and they aren't all a perfectly consistent diameter, so I came up with this dead simple tool to reliably line it up regardless of the actual hole diameter. The top large part has a tiny amount of clearance with the plate so you just thread this into each bolt hole, place the plate on, and bolt it down, then remove the alignment pin and you're good to go. (I actually paid a shop to make this for me a few years ago before I had a lathe, but ended up needing to modify it a bit now)
Then there's the issue of actually drilling. The timesert kit includes a drill bushing that you place into the drill plate to center the drill bit as you bore out the old threads. This is where the problem lies. The tolerances on this are not very good, and if you aren't using a mill the drill and tap will never stay perfectly straight. And the drill bushing being so close to the block deck means a small amount of play in the bushing is a large amount of play a few inches up where the top of the studs are.
So my solution was this much larger drill bushing that holds the drill bit and tap shanks 65mm above the block deck in an oil bronze bushing with a very tight clearance. (If I ever, god forbid, do block #4, I'll make this bushing thread into the deck plate to make it even more rigid, but for now this works really well.)
Here's a slightly better pic of the bushing showing it aligned with the original stud.
The studs are pretty much perfectly consistent all the way across. This job is TEDIOUS, probably 4 hours not spent the time fabricating the tools, hopefully I won't have to do it again any time soon. If anyone else has to do this though I could rent this tool set out since I will not be needing it anytime soon.
At one point in the process, somehow one of the inserts got caught up before it was all the way seated and I didn't notice until I'd run the seating tool all the way in, which deforms the outer threads a bit and locks the insert in place along with the red loctite. I used an extractor to remove it, then the insert broke off partway through so I had to drill out the remains. Fortunately the threads survived and a new insert was fitted and torque-tested by bolting up the torque plate.
Next up for the block is setting up the ring gaps, then final deburring and cleaning, then assembly.
I also overthunked my way into a different set of wrist pins. After talking to the folks at Precision Products Performance (Not to be confused with Precision Performance Products, who I accidentally called the first time) about this application I ended up buying a set of thicker walled tool steel wrist pins for a couple reasons. Firstly, they were one of the pioneers in using DLC coatings in engines a few decades ago, and they said they could not see any reason to use them in this application where the pin is fixed in the rod since there is just so little rotation happening between the pin and piston. Then, with the DLC, there is an elevated chance that the wrist pins "walk out" of the pistons during operation since the DLC would result in a much less sticky interference fit, and that usually means catastrophic engine destruction. And finally, wrist pins included with floating pistons are typically thinner walled and made of alloys that will begin to anneal at the temperature to which I'll be heating the rods. These new pins are about 10g heavier (119g vs 109g) but I think that is a worthwhile tradeoff.
