I installed head stud timeserts in my C30A engine block since the factory threads are prone to pulling out even without overheating and I'm upgrading to ARP hardware and MLS head gaskets which require more torque than the factory spec for the OEM graphite gaskets.

I had a custom alignment tool made to perfectly align the timesert drill plate with the holes in the deck because the included alignment pin is too small for the holes in the C30 deck, the tool worked perfectly, installation was time consuming but overall went smoothly.

I went back and measured how straight each insert is relative to the deck surface just to satisfy my repressed OCD tendencies and the worst was 0.6-0.75 degrees from perpendicular. There is enough wiggle in the head studs to get them perfectly straight and still thread in easily. As far as I can tell, I did everything right according to the directions and the only thing that could have caused this would be the play between the timesert drill plate, bushing, and drill bit. How much angle in the studs is too much?

Worst case scenario I'll just have the shop doing the block machining pull them out and do bigserts.

I'm done with trying to do stuff like this myself though, I should have realized that DIY timeserts are more for fixing an overheated corolla engine block in an autozone parking lot than for building a performance engine and left it to the pros who could get it 100% perfect. Live and learn I guess.

 

Put it together and send it !!! It should be fine.

 

Only a REAL NSX owner would measure how perpendicular their head studs are to their block in tenth of a degree increments lol. I think you're good brother

 

Drive that NSX by my apartment when you get the engine back together

 

You guys were right. Machinist said it was no problem and that the holes were likely drilled crooked from the factory. Bottom end is about to be reassembled.

Photos from machine shop.