i bought a set of arp rod bolts for an engine i'm reringing, they were cheaper than oem so i figured why not, but will i be ok if i just put the rods together and measure them to make sure they're round outside of the car, or should i take them to a machine shop?
It depends if you want to be sure that you won't have any problems later or what not.
You should have the big end of the rod checked for roundness and maybe have them resized to make sure.
i definitely want to prevent future problems, but will me measuring for roundness with a set of calipers be enough?
not really, i found after i pushed in new rod bolts things went out of round .0015 -.002"ish... Hard to measure with a caliper, especially a bore, I used a dial bore gauge.. I took mine to the shop and got them resized for 50 bucks. I used OEM rod bolts and ive read that ARP will make the rod end change size even more so your probably off to the machine shop.
I had my machine shop put them in and watched him measure. When torqued all up and measured they didn't change one bit from the OEM bolts. I didn't have to have any resized. I think I was lucky, but since he didn't have to do anything he only charged for pressing them in.