I am a novice builder building a Type 65. I have a 302 crate motor that I am using. I have very little experience working on motors, or on cars in general. I have a question relating to bolts for the motor and transmission mount, but my question is also an across the board question relating to the type of hardware to use.

I have the complete kit and it comes with motor mounts. It has a bag of six bolts included by FFR. Four are 7/16-14 for the engine and two are 1/2-13 for the transmission. They are grade 5; I learned that by doing a bit of googling and watching a YouTube. Three lines in the heads.

My question is should I replace with Grade 8, which I understand are stronger but less ductile? Or ARP so I get fancier looking bolts that come in cool packaging?

As a kid I took metal shop (back in the UK) and have always been into airplanes; from that interest I know what stress fractures did to the early British jets. So my thinking is higher strength is not always better. Given that the engine block is cast iron it is considerably less strong than steel and the same is true for my Tremec T56.

So I’m thinking that Grade 5 is more than strong enough, and may even be better because of all the vibrations that these bolts absorb. Am I wrong because once the bolts are torqued down friction locks them to the material they are bolting down and absolute strength rules?

Or should I just stop overthinking things?! That is my problem, I have some amount of book knowledge but no real practical experience!