WHy is it that studs are more prone to leak than bolts? arent they the same? I have done a search and found alot of people complaining about their studs leaking...they were replaced with bolts and the problem was solved..

the reason I ask is because I have ARP head studs in my block now awaiting my heads to come in from AFR...should I replace them with bolts?

thanks

 

studs are stronger and as long as you use threadsealer i dont see any reason why they should leak any more than head bolts

 

studs are better then bolts, but some cars won't allow head removal with engine in car if you use studs

 

Head studs don't get installed with much torque- they get threaded in basically screwdriver-tight, although you are supposed to use thread sealant on them just like a head bolt.

Personally, I think the problem most people run into is they install the studs, which aren't in very tight and the sealant sets up like that. Then they install the heads LATER and when they tighten down the nuts on them it appies pressure to the threads down below and sort of "unseats" the alread-dried sealant. Next stop- leak city, population you.

I used studs ONCE and I installed the heads immediately after the studs went in- no problem with leaks. Then I got it in the car, blew a head gasket and had to yank the heads...... boy, were those studs a stupid idea. Absolutely no way to get the heads off with the engine installed in the car. Ah, youth! All the stupid monkey-see, monkey-do stuff I used to sign up for. Every motor I've built since has used head bolts.

If, however, you are building a race engine and you need to take the heads off on a regular basis AND you have room to get them off with studs in place (a gutted engine bay, typical of a race car) studs can be your best friend. Head bolts WILL eventually wear out the threads in the block and strip out. Studs won't do that.

 

hmmm? so it would be a good idea to use bolts? this is no race car..it my daily driver during good weather....I have studs aand the typical f-body engine bay.....so what I'll do is sell them and get some good bolts and be done with it.

 

Bolts are certainly much easier to deal with. Just make sure you clean out the threads with a chase to get the old gunk out of them (or you'll never get an accurate torque on them), use proper sealant (enough to coat the thread- not blobbed on) and tighten down in the recommended sequence in 3 rounds of tightening- 35, 55 and 65.

 

do not ever, ever, ever, ever re-use head bolts.

What you are doing when you torque the bolt down is actually stretching the bolt and relieving the "preload" designed into the bolt. That is why they have you torque them down in increasing amounts. When you remove the bolt, it will not return to its original size (no preload anymore), so the bolt is now say 1/16" longer. If you reinstall the bolts, they stretch again from the torquing but instead of doing what they are supposed to..... they break, usually right underneath the bolt head or at the top of the threads.

now you won't break a bolt every time you do this, but there is a reason that manufacturers recommend that you not reuse bolts and that is why.

sorry if that was too long or over the top, i've just broken way too many bolts off in the wrong places on my car..... hopefully it will save someone a trip to the machine shop to get a head bolt drilled out

 

just to be clear,
the above post applies to "tty" bolts, thats "torque to yield" bolts, not all bolts are torque to yield but most are

yielding is what the bolts do when they stretch as jayman explained
but not all head bolts are torque to yield
i dont think arp's head bolts are torque to yield

 

NO FACTORY SMALL BLOCK CHEVY HEAD BOLT IS TORQUE TO YEILD. Neither are the ARP bolts.

I've reused factory head bolts half a dozen times with no problems whatsoever. Do NOT try this with a Ford or many other manufacturers- they're a different bag of worms.