main bolts replacement necessary?
main bolts replacement necessary? I am about to get my 6.0 iron block machined and was wondering if its necessary to replace the main bolts. Every one says a torque to yeild faster must be replaced every time its used?? Thanks
Joined: Nov 2001
Posts: 3,043
Likes: 0
From: Texas and Qatar
Main bolts are not torque-to-yield, although do rely on an angle-torque procedure for accurate bolt clamping loads (base torque of 16lb feet on all, then 80 degrees inner 13mm bolts, 53 degrees on outer 15mm stud bolts).
That being said, I myself do not like reusing main bolts that have been "run" and will replace them with new or take-out bolts that have not been heat cycled. I've had older '98-99 LS main bolts feel like they were stretching excessively by not "feeling" tight after doing the torque angle procedure, put in new bolts and that problem went away.
FWIW that specific torque sequence should leave the bolts at about 58-62lb feet of torque if you happen to check.
That being said, I myself do not like reusing main bolts that have been "run" and will replace them with new or take-out bolts that have not been heat cycled. I've had older '98-99 LS main bolts feel like they were stretching excessively by not "feeling" tight after doing the torque angle procedure, put in new bolts and that problem went away.
FWIW that specific torque sequence should leave the bolts at about 58-62lb feet of torque if you happen to check.
Using an electronic torque wrench that shows torque during angle-torqueing, I have tested the exact difference with "used" and "new" main bolts on the exact same main caps.
The torque reading was exactly the same between the two at proper torque angle. Both read right at 60lb of torque (both inside and outside main bolts which use different amounts of angle torque)
I still recommend replacing new as well.
The torque reading was exactly the same between the two at proper torque angle. Both read right at 60lb of torque (both inside and outside main bolts which use different amounts of angle torque)
I still recommend replacing new as well.
Last edited by CalSpeedPerformance; Sep 22, 2010 at 11:39 AM.
On The Tree
Joined: Aug 2010
Posts: 106
Likes: 0
From: Melbourne
Unless they are new and never ran, replace. Also don't use ARP moly grease on them. It's something most beginners don't know. But if used it will over torque the bolt and it may break during operation
Main bolts are not torque-to-yield, although do rely on an angle-torque procedure for accurate bolt clamping loads (base torque of 16lb feet on all, then 80 degrees inner 13mm bolts, 53 degrees on outer 15mm stud bolts).
That being said, I myself do not like reusing main bolts that have been "run" and will replace them with new or take-out bolts that have not been heat cycled. I've had older '98-99 LS main bolts feel like they were stretching excessively by not "feeling" tight after doing the torque angle procedure, put in new bolts and that problem went away.
FWIW that specific torque sequence should leave the bolts at about 58-62lb feet of torque if you happen to check.
That being said, I myself do not like reusing main bolts that have been "run" and will replace them with new or take-out bolts that have not been heat cycled. I've had older '98-99 LS main bolts feel like they were stretching excessively by not "feeling" tight after doing the torque angle procedure, put in new bolts and that problem went away.
FWIW that specific torque sequence should leave the bolts at about 58-62lb feet of torque if you happen to check.
