Re-torquing head bolts

Cold then after its warmed up after a nice drive ! Then again cold and after its warmed up! Just because there is so much out there, the best advice torque offen until the nuts stop turning.
 
The instructions that come with the head gaskets say, when a new head gasket is installed, to torque, then warm up the engine, then let it sit over night and re torque. They drive 100 miles, let it sit over night and re torque. Then drive 500 miles, let it sit over night and re torque. Then re torque in 6 months on a cold engine.

I have re torqued my head nuts several times and will continue to do so every year or sooner, on a cold engine.
 
nkaminar said:
The instructions that come with the head gaskets say, when a new head gasket is installed, to torque, then warm up the engine, then let it sit over night and re torque. They drive 100 miles, let it sit over night and re torque. Then drive 500 miles, let it sit over night and re torque. Then re torque in 6 months on a cold engine.

I have re torqued my head nuts several times and will continue to do so every year or sooner, on a cold engine.
Click to expand...

That's cool. I have never seen instructions come with a head gasket. May I ask what brand that is/was? Thanks.
 
back to OP ... Why? ( other than it says so on the instructions !), what's there reasoning for doing it cold ? Is it just that rebuilding of the engine is done at room temp and so
the torque value is at that temp or is there some metallurgical reason for it to be done cold ?
 
Last edited:
John, There is probably a metallurgical reason. It may be that the studs expand when hot. I am guessing. I know that the gaskets compress over time and that is the reason for re torquing.

Ruth, Snyders just updated their website and the link to the tightening guide is bad. I will try to provide a link when available.

Meanwhile, here is a link to another thread that discusses torquing the head bolts. https://fordbarn.com/forum/showthread.php?t=12673
 
With cast iron in both the block and the head, the temperature at which you tighten the head nuts doesn't matter a huge amount, but my preference is to tighten when cold because it helps ensure that the entire head is the same temperature. If all the components are the same temperature, that takes one variable out of the complex forces that determine the preload on the bolted joints being created by you torquing the nut to however many ft-lbs. This reduces the potential variation in preload across the head, which is good – you want it to be as consistent as possible. That's why I also lubricate the fine threads before I put the nuts on – not trying to get it tighter, but trying to get the preload more consistent.
 
alexiskai said:
With cast iron in both the block and the head, the temperature at which you tighten the head nuts doesn't matter a huge amount, but my preference is to tighten when cold because it helps ensure that the entire head is the same temperature. If all the components are the same temperature, that takes one variable out of the complex forces that determine the preload on the bolted joints being created by you torquing the nut to however many ft-lbs. This reduces the potential variation in preload across the head, which is good – you want it to be as consistent as possible. That's why I also lubricate the fine threads before I put the nuts on – not trying to get it tighter, but trying to get the preload more consistent.
Click to expand...

Very intelligent for sure!
 
Good point about the entire head being same temp when cold.; hadn't appreciated that .... but of course that leads to the corollary .. that the head and bolts may expand variably when hot so the consistent torque at cold is no longer consistent when hot ! ;). Oh what the heck the let's just drive 'em!!:D
 
Stuff moves around after initial assembly in this case due to heat cycles. Expansion and contraction. So a torque check or "re-torque" just takes up any slack, so to speak. This can take a few iterations. Continue till they don't move. The Operator's manuals always used to emphasize checking wheel lug nut torque on a new car particularly after the first few hundred miles.
 
Last edited:
You must log in or register to reply here.
Back
Top