Head Studs

[woodyedmiston]

When rebuilding the 4.0 I looke at the all-thread cylinder head bolts and sort of get queasy. I'm sure a Ford engineer somewhere penciled that all out and it's OK and the quick fix is new bolts. BUT . . .

I've read a description of how they are supposed to work and wonder how that squares with occassional retorqing the cylinder heads.

Has anyone put studs in the heads? Got a part number from a bolt house?

Got thoughts, feelings, emotional upheavals on the topic?

 

[Psychopete]

Not sure why you'd need to occasionally retorque the head bolts?

If you use studs, and you try to remove the heads w/ engine in the truck, this might not be all that easy than if just head bolts were used (too much stuff in the way). You might not even be able to get them off w/o pretty much pulling the engine out to get clearance.

On the other hand, you can get them torqued more closely to specs and head alignment to block would be a breeze.

Unless you're doing something exotic, I would recommend just going w/ normal tty head bolts.

FWIW, I used ARP head bolts on my 5.0L build w/ the stepping washers since my heads (GT40) had been modified to fit a 351W.

Pete

 

[Doug904]

When rebuilding the 4.0 I looke at the all-thread cylinder head bolts and sort of get queasy. I'm sure a Ford engineer somewhere penciled that all out and it's OK and the quick fix is new bolts. BUT . . .

I've read a description of how they are supposed to work and wonder how that squares with occassional retorqing the cylinder heads.

Has anyone put studs in the heads? Got a part number from a bolt house?

Got thoughts, feelings, emotional upheavals on the topic?

This has been tried along with even normal Grade 8 bolts with the same results, not good enough. The Torque to yeild bolts have more of a purpose then just being thrown away after use, they stretch to a point that helps keep the proper torque on the heads and the gaskets.

I guarantee you haven't gone through the number of cylinder heads or gaskets that I have on a 4.0 and I still to this day simply buy new bolts, every other time

 

[woodyedmiston]

Re-torquing the bolts is just something you do on engines that have head gasket problems in the world where I live - a lot of stuff is dusty in here, so I apologize for my ignorance. I've never heard of an engine rebuilder till now that does not recommend retorquing after run in on a motor that's not going to be disassembled at the end of a race. That whole torque to yield idea for someone without an engineer's understanding just doesn't set well. If however, Doug904 says "every other time" that makes me feel better. I'll take the combined advice and go buy some bolts. Thanks Pete.

But - all bolts stretch - so what is different about the torque to yield if you don't mind going down a purely academic route.

 

[JohnPi]

When a bolt yields, the stretch is permanent. If you don't yield the bolt, it will contract back to it's original size (approximately).

 

[MAKG]

Re-torquing the bolts is just something you do on engines that have head gasket problems in the world where I live - a lot of stuff is dusty in here, so I apologize for my ignorance. I've never heard of an engine rebuilder till now that does not recommend retorquing after run in on a motor that's not going to be disassembled at the end of a race. That whole torque to yield idea for someone without an engineer's understanding just doesn't set well. If however, Doug904 says "every other time" that makes me feel better. I'll take the combined advice and go buy some bolts. Thanks Pete.

But - all bolts stretch - so what is different about the torque to yield if you don't mind going down a purely academic route.

The real world isn't the same as race engines. Real people tear down the engine MAYBE once per 200,000 miles. Many race engines will never get anywhere near that mileage, and are much more prone to breakage and wear due to one-off engineering.

Torque to yield bolts do not respond well to -- nor do they need -- retorquing.