ATVracr

iTrader: (5)

Like the title says, I 'm considering it to make sure the heads dont lift on a bigger shot.


Thanks in advance for any input

mr2guru

iTrader: (16)

80 is enough....if you're still having problems it may be the cyl head bowing. If that is the case go with a thicker decked head.

ATVracr

iTrader: (5)

I have heard of people doing it, not saying I'm going to just wondering if anyone has done it with any success.

Beast96Z

iTrader: (21)

I did 80 with oil, but wouldn't go any higher. The threads of the block can only handle so much. Like guru said, if your having problems, then get a AFR casting. If your using th eARP moly base, I wouldn't go over 70.

GMPerf

If you have a newer set of studs, you can go 85lbs with oil. Just lube under the washer, on top of the washer and the threads...

ls1290

iTrader: (20)

Why in the world would you apply more than 65# when ARP says you should use that much

Keith

ATVracr

iTrader: (5)

So you dont "lift" the heads

2001CamaroGuy

iTrader: (6)

more preload........BUT for 99.99999999999% of people that's not an issue..........most everyone (everyone I know and myself personally) just uses the ARP recommendations and never see a problem.......


the question to ask would be "what application are you doing that you think you will need the added clamp force?"


one thing to think about, cylinders are bored with "X" amount of pressure on the deck/cylinder walls/web which is provided by a "Y" amount of preload on the bolts.....if you now go and do "Y"+"Z" preload, you will now be over the pressure which the cylinders were bored for and you will pull the bore out of round............you can't just change one thing and expect it to not change others........

GMPerf

Not sure if you are talking to me...
But ARP's instructions call for 85lbs with oil, or 70lbs ARP lube.

ls1290

iTrader: (20)

My set of ARP instructions say 75# for oil and 65# for ARP assembly lube for aluminum heads and 85# 70# for iron.

Keith

MrDude_1

iTrader: (4)

you want to make sure your bolts are working to their peak?

properly clean the threads. properly lube it.. then TQ it to what the ARP specs are.




over-tightening a fastener does NOT make it "hold the head down more"
it just invites failure.
the ARP studs are actually stronger then the head the head itself will flex before properly installed ARP bolts will give. over-tightening them will not gain you anything besides increased chance of bolt failure. ESPICALLY if you're pushing enough power to bow the heads.

GMPerf

Keith depends on how new the packs are... They have gone up recently... Best thing for anyone is just read the instructions and stick to them

bowtieman81

iTrader: (35)

First disclaimer: I would follow the ARP instructions supplied with the studs. They make them and they know best how to use them.

With that said, for any fastener you will get the max clamp load by tightening (stretching) it right up to yield. Chances are you can get a little more clamp force on the studs by tightening them more than 85 ft/lbs. But, how much more you can tighten them depends on several other factors.

Bottom line: I would follow ARP instructions, but choice is yours.

robertbartsch

I used stock bolts for my H/C swap. I sprayed the bolts with silicone before installation and then realized i could not mark them with a felt tip pen for purposes of torking them to GM specs.

So I just titghted the bolts 40lbs, 50lbs, 60lbs, 70lbs and finally 75lbs. I used an inside out sequence - just like the old days....

My heads have been on for 3 years with no issues.

I was always curious about the final recommended factory tork spec for GM bolts. I assume 75lbs with silicone is about right.

Should I be loosing any sleep?

Slowhawk

iTrader: (12)

We torque all the ARP studs to 80 ft/lbs ussing there lube.Most of the motor's are FI and none of them have lifted a head while running 700+hp

mr2guru

iTrader: (16)

I am going to torque mine to 150ft/lbs, more is better right?

robertbartsch

does anyone know the true factory torque spec for factory head bolts,,,,,,

The tork then twist the bolt a certain number of degrees is confusing becuase it does not yield a final tork number....

bowtieman81

iTrader: (35)

The final torque spec does not matter. The whole point of a torque turn procedure is to get the proper amount of bolt stretch, not torque. I have personally checked breakaway torqe on TTY bolts and it can vary +/- 15% from the average value. Only 10-25% of the energy put it into tightening a bolt actually goes into stretching it, the rest is ate up by friction, thread imperfections, etc.