Cylinder Head Bolt Torque

[jdkoontz]

So I've read and understand the torquing procedure for bolting the cylinder head to the 4.0L blocks. I've worked on a couple Chevy 250's.
The spec's call for 110/100 ft-lbs with dry threads.
I've been reading that using lube of any kind will reduce the requirement of torque by as much as 40%??
The specific lube of using 10W30 and just a light oiling of the threads reduces the torque in this 30 to 40% range.
Anyone follow or use this type of reduction in torque??

 

[R49]

If the specs call for dry threads, don’t lubricate them.

 

[sab]

If the specs call for dry threads, don’t lubricate them.

+1

Cylinder head bolts and rod bolts are the two bolts on a vehicle that get torque-tested by the manufacturer's engineers (I have been that engineer at times) relentlessly due to the stresses they see, combined with the number of load cycles. I always follow the exhaustively-tested procedure without variance.

 

[jdkoontz]

My thinking was; "how man of those engineers did stress studies with a block that has 190,000 miles?"
I see bolt holes in the block with different looking threads, some with rust, some with pitting and some look OK.
So to get a consistent torque/stretch on holes/threads that not consistent, they may need some help?
Just thinking this through before grabbing the torque wrench!!

 

[sab]

My thinking was; "how man of those engineers did stress studies with a block that has 190,000 miles?"

Having not worked for Jeep, I can't answer that. However, I can say that most manufacturers' development programs include extensive durability testing, both in-vehicle and on the dyno. Dyno testing is usually done to pretty high run times (time=miles on a dyno), to include re-building engines multiple times in the process.