ARP headbolts
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Joined: Aug 2006
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From: St.Peters Mo
ARP headbolts 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).
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From: Cape Girardeau, Missouri
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.
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).
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.
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.
Last edited by Paul Bell; Jan 19, 2012 at 08:06 AM.
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From: Katy, TX
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.
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Verdad Gallardo Good call.
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.
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From: Katy, TX
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.
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.
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.
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.
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.
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.
Washer with undercut chamfer for clearance of radius fillet in bolt:
Crankshafts have these same features on journals and have matching bearings.