Originally Posted by pinkytoe69

Which is why you read instructions and put the ARP ultra lube on the threads and surfaces of the washers.

Originally Posted by sidescrollin

It's the middle of the day and my mind is elsewhere, so someone school me if i am just brain farting.

I'm seeing a lot of people talking about stats and don't get it. How does a thermostats initial opening and full opening affect running temp??? A thermostat that opens at 5 degrees and is wide open at 10 will have the same running temp as a stat that opens at 120 and is wide open at 160. Obviously there is a threshold safe for an engine, you don't want it to open at 500 degrees because the engine will have long overheated.
But generally the operating temperature of a gasoline engine is 190-210 degrees.

the stock stat opens at 179 and is fully open at 204. Obviously it opens before the desired running temp because it needs to be fully open and opening before gets rid of any shock that would result from it taking a moment to start cooling the system. And because 179 is an acceptable running temp (if it were cold outside)

either way the running temp depends entirely on the cooling systems capabilities. less than 180 is regarded as less than ideal for the engine, so if the stat opened at 150 in the winter, the cold winter air would keep the engine at possibly whatever the lowest settings the stat opens. In hot weather the engine will continue to heat to whatever its cooling system can maintain, so all the opening temp does is relieve some stress from running up to operating temp and possibly past it until the cooling system has time to run the temp back down as well as allowing the engine to heat up. If an open stat was placed into a system when it was hot the operating temperature would be IDENTICAL it would just take longer to warm up, which is bad.

So unless we are all worrying about putting a higher temp stat in for the winter, or a stock one in for summer driving, wtf does installing a lower initial opening thermostat do?

people act like if they could get their hands on a 5 degree thermostat there car would run cooler. that makes no sense

sorry for the rant lol

Originally Posted by sidescrollin

torque to yield bolts become plastic instead of elastic when used. Clamping force is consistent when a bolt is tightened to plastic deformation. This is especially beneficial to aluminum heads as they expand and contract a lot.

In other words, when an aluminum head is fully expanded the clamping force of a torque-to-yield bolt is much closer to what it was when the head was cold than a bolt torqued into its elastic range. A bolt or stud that is still in an elastic state can move and its clamping force can change.

Common thought is that this stretching results in the bolts stretching along with the heads and giving a consistent clamping force, this is untrue. Clamping force rises, which puts much more stress on the bolt holes as the studs/bolts essentially tighten as the head heats up and then become looser as it cools.

Seems like everyones thought process is bigger badder studs that can be tightened more must be better........there is a reason studs were common place 60 years ago and all of todays engines use torque to yield

I have also seen tips on installing Disco cylinder heads about using teflon on the bolts and torque to the same settings on all the bolts instead of using the factory specs. This is wrong. The reason it is 15 lbs + 90 +90 is that turns of a bolt are much more consisent than torque. think of 15 lbs as defined for the bolts being "seated" and then the 90 degrees and 90 degress makes sure ALL bolts are tightened the same amount and share the clamping force. Telling LR engineers to **** off and recommending everyone to tighten to 50 ft/lbs or 35 or 80 instead is retarded. bolt torque is too dependent on friction to use on something as unforgiving as a cylinder head ( also much worse with different sizes of bolts = different amounts of friction), which is why this is now common practice.

Originally Posted by 04duxlr

This is true. TTY bolts rely on the material properties of the bolts to provide a more consistent and uniform clamping pressure by eliminating the variation in thread condition, friction in the threads and beneath the bolt heads, etc. One of the problems with the LR blocks seems to be the condition of the threads. It may be that the threads get spalled and corroded so that they are weaker when the head gaskets are redone. Another problem as Robison showed in his cutaway is that the holes may be too close to the cylinder wall. Either way, the stress of advancing the threads into the block seems to cause issues in some cases. Ideally, the perfect fastener would be a TTY stud where you get the consistency by using the properties of the material to provide the clamping force while at the same time reducing the stress induced in the threads within the block.