head gaskets and bolts
04-12-2009, 12:41 PM
#1
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head gaskets and bolts i just put my heads on last night with new arp head bolts and i put them in dry no moly lubercation 30 sae oil. should i take them back out and reinstall them with lubercation and will i need new head gaskets? or run it like it is?
Last edited by melroy293; 04-12-2009 at 04:24 PM.
04-13-2009, 07:23 AM
#2
Yes you need to remove the bolts and correct this. Gasket replacement will depend on type of gasket used. Here is what I would do. Remove the bolts in the tightening order one at a time (start with position #1), lubricate properly using the ARP lube, then re-tighten to 30 lb-ft and move to the next bolt in sequence. Once they are all installed to 30 lb-ft with lubricant, follow the torque sequence in steps to the final value.
Here is what you did. Measuring torque when you tighten the bolt is a method of measuring how much preload (clamping force) you are putting into each bolt. The torque is very dependent on friction. So by installing them dry, even though you reached the correct torque value on the wrench, the actual preload (clamping force) is greatly reduced because the dry friction is so much higher than the lubricated value. So by using the procedure above, you will be inserting lubricated bolts one at a time and bringing them to a lower preload then the final value but the preload is in the neighborhood of your current preload dry preload. Then you can work up from there and "hopefully" your gaskets will be OK.
Bottom line, the heads currently have way too low a clamping force and need to be corrected. Hope this all makes sense.
Here is what you did. Measuring torque when you tighten the bolt is a method of measuring how much preload (clamping force) you are putting into each bolt. The torque is very dependent on friction. So by installing them dry, even though you reached the correct torque value on the wrench, the actual preload (clamping force) is greatly reduced because the dry friction is so much higher than the lubricated value. So by using the procedure above, you will be inserting lubricated bolts one at a time and bringing them to a lower preload then the final value but the preload is in the neighborhood of your current preload dry preload. Then you can work up from there and "hopefully" your gaskets will be OK.
Bottom line, the heads currently have way too low a clamping force and need to be corrected. Hope this all makes sense.
Last edited by vettenuts; 04-13-2009 at 07:30 AM.
