1mean96ss

Ok so i installed my heads last weekend and in doing so i used the GM torque procedure and found one of my washers was bad. Questions are; are the bolts ok since they are obviously tighter than the recommended torque on the sheet included in the kit, and if they are not and i replace them are the headgaskets still ok (motor is still on the stand).

KCS

iTrader: (20)

You used the GM Torque Angle procedure on ARP head bolts?!

Cape T/A

So it sounds like you know that you messed up I hope... you should have used the arp tq specs. As for the head gasket, i would just swap the bolts without moving the head and you should be ok, but I am no expert on the matter. Get some more opinions.

JPH

iTrader: (2)

You should have followed ARPs torque specs along with there lube and used GMs torque pattern. The chamfer side of the washer goes ^up. Yes, don't be afraid to reuse a head bolt and get a new washer if needed. Sounds like you need to crack them ALL loose and start over anyways.

RezinTexas

It sounds like your ARP bolts are now stretched in the same way an OEM bolt would be. Check your thread pitch when you pull them out. They are probably trash.

Paul Bell

iTrader: (9)

GM head bolts are designed to stretch, ARP bolts will not, especially when torqued into an aluminum block. You should be using the ARP recommended lube and torque specs for this job. You'll also need a dab of lube under the head bolts-between them and the washers.

How did you damage a head bolt washer?

While I agree you should just be able to loosen all the bolts and re-torque and the head gasket should be fine, contact the gasket maker and confirm.

parks450

iTrader: (17)

Reuse the bolts their fine, their not TTY and their 200,000 psi strength for a reason. Head gasket is fine, just loosen them and retorque wothout pulling the head off.

RezinTexas

Well I hope I'm wrong, but if he followed the GM procedure using an angle gauge, the bolts are not "torqued" to a value, they are stretched to achieve the same elongation that a GM bolt would have. Hopefully the bolts have not been yielded.

1mean96ss

ARP said my bolts are trashed, from being over torqued. got a new set coming and gaskets as well.

KCS

iTrader: (20)

All bolts are designed to be stretched; think of a bolt as a spring. TTY bolts are typically designed to be stretched to their Yield Point, ARP's are typically designed to be stretched to roughly 75% of its Yield Point. Either way accomplishes the same result of applying a preload to a joint.

Good call.

Paul Bell

iTrader: (9)

HMMMM really? You stretched 200,000 PSI ARP Pro Series head bolts while turning them into an aluminum block? You'd pull the threads out of the block before these bolts passed their yield.

I think they want you to spend more money.

HOWEVER, it is better to err on the safe side, even if it costs you some bucks. If they say you broke their bolts, then so be it.

RezinTexas

If you have enough thread engagement in the block, the bolt will yield before the block threads will. Its all a matter of force applied over a given amount of area of material. Yeah aluminum is only 36k yield (or so) but there is probably >10x the amount of area (vs the cross section of the bolt) after the bolt is threaded all the way in.

Paul Bell

iTrader: (9)

Perhaps. I have seen these threads damaged on these blocks and not from still having fluids left in them.

Still, the OP is erring on the side of caution.

1mean96ss

Speedinc had the bolts for 150 w/free shipping and GM gaskets were cheap, better to be safe then spray it and lift the heads

GNIUS

iTrader: (2)

Finally a comment that makes good engineering sense!!! Good job at providing useful info.

Paul Bell

iTrader: (9)

I was also very impressed with Rezin's post. I believe that a nut height 1.5 times the diameter of the thread is considered stronger than the bolt itself.

splitfinger09

iTrader: (9)

Good info here. I put mine in all different ways cause I didnt know about the chamfer. I torqued to ARP specs, but ended up pulling one bolt at a time checking the washer and then putting it back in to final torque value. 3000 miles so far so good.

GNIUS

iTrader: (2)

This is true. When designing a bolted joint standard engineering practice is 1.5x diameter for a steel thread/studs/bolts and 2x diameter for threaded joints in aluminum.

S10xGN

iTrader: (11)

That chamfer is actually a "relief" for the fillet under the bolt head. With the washer installed upside down, the fillet will grind into the sharp edge of the washer. Not only will this skew the torque value, but it could damage the bolt head.

Paul Bell

iTrader: (9)

Bolt with radius fillet between the head and body:

Washer with undercut chamfer for clearance of radius fillet in bolt:

Crankshafts have these same features on journals and have matching bearings.