47 flathead head stud torque specs and tighten order

[Dmac2590]

Can anyone help me out with this I can't find anywhere what the torque specs are for a 47 251 and what order to tighten the studs.  My manuals haven't came in yet.  

[greg g]

Initial torque is 70 #ft.  The sequence starts in the center of the head and works outward in a star pattern. Looking at the head from the passenger side

 

17, 11, 5. 2, 8, 14, 20

16, 10, 4, 1, 7, 13, 19

18, 12, 6, 3, 9, 15, 21

Do three go around, with the wrench set at , 30, then 55, then 70.

It is very important to retorque in the same pattern after the engine is started and brought to operating temp. Then again after a third or fourth heat cycle.

The jury is out as to whether to use gasket sealant, grease, or bare in the gasket and whether it is necessary to put thread sealer on the bolts that go through coolant passages.  I sprayed the head side of the gasket with copper gasket spray, and did not use any sealer on the head bolts. No issues in 40k miles.

Good luck!

[Dmac2590]

Thank you for the help.

[Don Coatney]

Do you have bolts or studs with nuts? Bolts are at 70# studs are at 55# due to the fine SAE threads.

[Matt Wilson]

I spoke to George Asche a few months ago, and he said he tightens up the head bolts or studs in 10 in-lb increments.  I guess he feels like that this sandwiches the whole gasket more evenly.  Kind of a pain, but intend to do that on mine.  He is a wizard and the most experienced person I know of with these engines. 

[greg g]

Well you should have muscle memory of the sequence/pattern after the fourth time through.   Each to his own,guess I'm less finicky, but that method certainly won't hurt anything.

[40desoto]

On 5/5/2017 at 9:53 AM, Don Coatney said:

Do you have bolts or studs with nuts? Bolts are at 70# studs are at 55# due to the fine SAE threads.

Don, i heard that every manufacturer specifies different torque specs.  Im using ARP studs and my mechanic believes the torque spec is specified by manufacturer and that studs should have higher torque specs that stock bolts.  

Your statement regarding studs at 55# matches what I discovered when I researched my 7/16  14 and 20 thread studs.

 

do you have any insight on whether torque specs are defined by the manufacturer?

[martybose]

I'm with Don on this subject.  When I purchased my ARP studs they did not specify a torque setting, so I went with the factory spec for heads with studs, which as Don mentioned is 55 lb/ft.  The issue is clamping force, and with a finer pitch on the nuts they don't need as much torque to produce the required clamping force.

 

Marty

[chrysler1941]

Here you go

Edited July 28, 2019 by chrysler1941

[40desoto]

Great!  Thanks to all for this great input. Would of never imaging that studs would use less torque to tighten than bolts. 

Now that its explained it makes sense.

[Dodgeb4ya]

Course thread 7/16" X 14 TPI  cap screws are 65 to 70 lbs as mentioned above.... 

Studs with 7/16" X 20 TPIi fine thread are 55lbs.

Cylinder head clamping force ends up the same for both styles.