I installed my forged 347 about 2 months ago and have put about 3k miles on it with basically no issues except a very slow oil leak.

One thing that has bugged me though...

When doing the head stud install, several of the big nuts "slipped" while torquing to 80 ft/lbs. Like they would hit 20-40 ft/lbs or so, then I would feel the wrench slip and it felt like there was no torque applied on the nut, I would keep tightening and they would get tight again and would torque just fine all the way to 80 ft/lbs. I never heard any pops or anything, but that "slip" scared me as that normally means something let go.

I am not leaking or burning coolant and other than the minor oil leak, everything appears fine.

Has anyone had this experience installing studs? I am just hoping there isn't a crack in that area and that is causing my oil leak? I don't even think oil could leak from such a high area on the block though.

Probably me just being paranoid again.

 

I've experienced this as well. Sometimes it happens, sometimes it doesn't...I've had the heads on and off multiple times over the course of my build so far. It's just the stud "finding its home" in the block, seating itself in the bottom of the threads. this is the reason it's not recommended to tighten the studs more than finger tight prior to tightening the nuts. If the stud wants to move when you're already bottomed out, that's when you deform threads. It's also really important to make sure everything is clean / there's no oil or other fluid at the bottom of the hole. Hydraulic pressure buildup can cause the block to crack.

 

That is what I figured it was. Thanks for the reassurance. The block was fresh from the machine shop, so I assumed it was pretty clean. I did blow the holes out with compressed air, but maybe there was still some old sealant in there from the factory GM bolts. I bottomed out all the studs, then I backed them out a bit before I put on the nuts.

I figure since they all torqued to a massive 80 ft/lbs, that there is no way anything cracked, but it still bugged me .

 

if something let go, you'd definitely know it.

 

I had a arp stud break on my in the final torque sequence, but luckily I was able to use a easy out and back it out. Talk about making you a lil gun shy the next time I torqued them lol. All went well though.

 

odd, seems like you didn't bottom those studs completely before putting the nuts on.. Maybe a little debri held it up, if it torqued to 80 then your good, if you woulda stripped threads it wouldn't of went to 80 lbs on you imho

 

What ever happened it was the friction that was present, let go.

Like you said, I guarantee if you stripped something, they would not have made it to 80ftlbs.

I honestly think you didn't clean the threads good enough or at all. The stud was not all the way down and bottomed out. The friction was enough to sustain low torque but when you started to go up, the stud rotated in the block causing a "came loose" sensation. I feel its a non issue.

A lesson for others to follow. That internal wrench on top of the stud shouldn't ever "need" to be used. They should go all the way in with no resistance with your fingers.

 

ARP used to recommend torque-cycling the lubed nuts & washers at least 5 times before finally torquing them, in order to overcome the friction between the washer "top" and nut "bottom". I still do it, even though ARP claims their new lube doesn't need it...