The Ford Barn

daveymc29 · 10-09-2021, 10:17 AM

Do you torque with engine hot or cold? Why?

CarlG · 10-09-2021, 11:40 AM

Cold, 'cause that's what my engine builder put in his instructions,

Big hammer · 10-09-2021, 11:52 AM

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.

nkaminar · 10-09-2021, 05:18 PM

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.

Ruth · 10-09-2021, 07:41 PM

Quote:

Originally Posted by nkaminar

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.

That's cool. I have never seen instructions come with a head gasket. May I ask what brand that is/was? Thanks.

johnbuckley · 10-10-2021, 03:50 AM

Sponsored Links (Register now to hide all advertisements)

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 ?

nkaminar · 10-10-2021, 07:07 AM

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

alexiskai · 10-10-2021, 10:56 AM

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.

McMimmcs · 10-10-2021, 11:06 AM

Quote:

Originally Posted by alexiskai

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.

Very intelligent for sure!

johnbuckley · 10-10-2021, 11:51 AM

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!!

Crankster · 10-10-2021, 01:32 PM

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.

10-09-2021, 10:17 AM	#1
daveymc29 Senior Member Join Date: Sep 2010 Location: Danville, CA Posts: 1,553	Re-torquing head bolts Do you torque with engine hot or cold? Why?

10-09-2021, 11:40 AM	#2
CarlG Senior Member Join Date: Nov 2010 Location: Anchorage, Alaska Posts: 9,115	Re: Re-torquing head bolts Cold, 'cause that's what my engine builder put in his instructions, __________________ Alaskan A's Antique Auto Mushers of Alaska Model A Ford Club of America Model A Restorers Club Antique Automobile Club of America Mullins Owner's Club

10-09-2021, 11:52 AM	#3
Big hammer Senior Member Join Date: Jun 2014 Location: Land of Lincoln Posts: 3,127	Re: 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. __________________ Don't force it with a little hammer tap, tap, tap get a bigger hammer tap done

10-09-2021, 05:18 PM	#4
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Re-torquing head bolts 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. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

10-10-2021, 03:50 AM	#6
johnbuckley Senior Member Join Date: Jul 2010 Location: United Kingdom Posts: 1,441	Re: Re-torquing head bolts Sponsored Links (Register now to hide all advertisements) 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 by johnbuckley; 10-10-2021 at 11:47 AM.

10-10-2021, 07:07 AM	#7
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Re-torquing head bolts 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 __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

10-10-2021, 10:56 AM	#8
alexiskai Senior Member Join Date: Apr 2018 Location: Mebane NC Posts: 2,350	Re: Re-torquing head bolts 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.

10-10-2021, 11:51 AM	#10
johnbuckley Senior Member Join Date: Jul 2010 Location: United Kingdom Posts: 1,441	Re: Re-torquing head bolts 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!!

10-10-2021, 01:32 PM	#11
Crankster Senior Member Join Date: Oct 2017 Posts: 563	Re: Re-torquing head bolts 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 by Crankster; 10-10-2021 at 01:41 PM.