Torque setting for aluminum heads?

[36tudordeluxe]

Have a set of Kearney aluminum heads for my 21 stud, is 45lb. the correct torque amount?

[Jack E/NJ]

85 Horsepower V8 with Aluminum Heads.............................. 35-40 ft lbs

45-50 is what I use on my 21 stud iron heads


Jack E/NJ

[36tudordeluxe]

Originally Posted by Jack E/NJ

85 Horsepower V8 with Aluminum Heads.............................. 35-40 ft lbs

45-50 is what I use on my 21 stud iron heads


Jack E/NJ

Thank you

[Don Rogers]

Here's the diagram that I have used for years. It was taken out of a mid 30's Ford Field magazine article written by Murray Fahnestock. Torque sequence is very important to insure a leak free seal.

[V8COOPMAN]

Originally Posted by 36tudordeluxe

Thank you

Here's Ol' Ron's take on it. DD

_______________________________________________

11-12-2012, 10:40 PM #16 Ol' Ron
Senior Member



Join Date: May 2010
Location: Chester Vt
Posts: 5,403


Re: The reality of the torque sequence
I'm supprised how many times this comes up. Torque to #45 in 3 equal steps. Then re-torque through 3 heat cycles. Start fron the middle and work out. Over torquing can cause deck warping and broken Bolts/studs. Now how many of you have broken a stud or bolt when torquing to 55-65 lbs.??

[V8COOPMAN]

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Originally Posted by Don Rogers

Here's the diagram that I have used for years. It was taken out of a mid 30's Ford Field magazine article written by Murray Fahnestock. Torque sequence is very important to insure a leak free seal.

This is one of the strangest SEQUENCE charts that I've ever seen. DD

[Paul Bennett]

I recall being told back when that while the tightness is primarily to insure the gasket doesn't leak, that aluminum deforms ten times more than steel and over-tightening aluminum tends to damage the heads and doesn't serve to provide a greater seal. I'd personally choose 35-40. Also aluminum heads should be retorqued after heat up more times than steel heads to insure long term gasket life. Admittedly times change, TorqueToYield bolts are the in-thing and I'm living in strange times trying to remember a previous century.

[Ol' Ron]

Lets be logical. If 45 foot lbs work, for what reason would you what to tighten more??. I do this for 3 heat cycles or more, until I don't get any movement. The reason I do this is because the block has various thickness and over torquing can cause the block to deflect in these areas. Weather this is true or not id material because the 45 ft/lbs works for me and I've been doing this for the past 50 or so years.You might want to consider the 392 Hemi, 10 bolts at 100lbs = 1000 pounds clamping force VS 24 at 45 = 1080. Now that's logical

[Jack E/NJ]

Yeah but we only got 21 studs at 45. Only 945. Oh-oh! Better make it 48 just in case. 8^) Jack E/NJ

[36tudordeluxe]

I went to 45lbs. and used then torque sequence as shown on Vanpelt site.

[DavidG]

Here's another sequence which avoids tightening adjacent nuts except for the first two, unlike the Fahnestock version.

[OLD AS I]

Following a run time do you retorque with the engine at operating temperature for either alum or steel heads or only when cold ?

[JWL]

Always torque or re-torque when things are cold. If a good lube was used at time of assembly there is probably no need to "back-off" before the final re-torque tightening. However, it is a good practice at cycle #3. And, I agree, 45 ft. lbs. is adequate.

I do not think a strict adherence to a specific tightening sequence is a critical factor. It is, however, essential that the bolts/studs be worked down incrementally, evenly, etc. There have been a number of sequence charts for our Flatheads ranging from various center-outward scenarios, to, from one end to the other end. Any of these will work fine if used properly.

JWL

[rotorwrench]

On aluminum parts with torque settings up into the Ft/Lbs scale, it's a good idea to start the torque up process in increments. This is probably more important with softer composition head gaskets but still holds for copper gaskets. Start at a lighter torque setting then move up to another in sequence. Aluminum is a lot more flexible that iron.

[V8COOPMAN]

JUST TO BE CLEAR...........Let's not confuse 45 FT LBS TORQUE on a head fastener as meaning the same thing as 45 POUNDS of CLAMPING FORCE applied to the head......NOT THE SAME THING! DD

[Jack E/NJ]

Originally Posted by V8COOPMAN

JUST TO BE CLEAR...........Let's not confuse 45 FT LBS TORQUE on a head fastener as meaning the same thing as 45 POUNDS of CLAMPING FORCE applied to the head......NOT THE SAME THING! DD

Very true. And I think 45 ft-lbs tork on a 20tpi stud nut will exert a higher clamping force than 45 ft-lbs tork on a 14tpi bolt. Due to mechanical advantage. I think. Maybe. 8^) Jack E/NJ

[JSeery]

Clamping force is dependent on a lot of factors, among them thread pitch and lubricated vs dry torqueing. It also be depends on the fastener material. In general terms the following values will give you an idea of clamping forces.

[40cpe]

And Jack E/NJ brought up a point in a previous thread that the same torque on a next size smaller bolt will yield more clamping force than on the larger bolt.