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Retorqueing heads


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I have aluminum heads and am using copper head gaskets. The head gasket manufacturer recommends retorqueing. I never had to do this on my L-6 and it's been at least 20 years since I have played around with V-8's and what I remember is that you use the tightening sequence, break the bolt loose and retighten it to the proper torque. Is this correct?

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Hmmm...that's new to me.....I have always just added 5lbs to the torque wrench setting and nipped them all up a bit more. Usually get very slight movement on the head bolts....On the initial torquing of the bolts I stay on the low side of manufacturer spec range, so by adding 5lbs, I am just moving to the high side....

Tim

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We have to do that at work when we are torquing down a cylinder head on a diesel. First we TQ it to specs then loosen them all up. Now you should be doing this on a bone cold engine so that you dont warp anything. Just loosen them in reverse order of the head torquing sequence and you will be fine. Once they are all loose just torque them down like you did the first time.

 

 

Guy

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Tips (take them or leave them):

 

You can buy no-retorque head gaskets, like from Felpro. Then you don't have to retorque.

 

Make sure the head and block are scraped completely clean.

(Dont use a wire brush on aluminum).

 

Don't use compressed air.

 

Keep particles off the pistons and out of the valve guides using rags, paper, or tape.

 

Always torque cold.

 

Better to buy new bolts now then to take a broken bolt out. http://www.arp-bolts.com

 

If any bolt is rusty, streched, damaged or looks bad, replace all of them, and clean the threads in the block (run a tap lightly through it.)

 

You should step your torque: say the torque spec is 60ft-lbs, first torque 20, then torque 40 then 60 through the entire sequence each time.

 

Don't use a sealer on the head gasket.

 

If you need to retorque (per the gasket manufacturer) then you can loosen per sequence, and retighten same as before.

 

Don't go to the maximum recommendation unless you have new bolts.

 

Just some suggestions that will keep you from a lot of extra work and downtime. :wink:

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In my personal experience....... I refuse to use a clicker wrench on head bolts. I use the old school needle type cause the click wrech lets of the pressure. When you use the needle type it holds the presure till you let off. Every motor Ive built I used the needle. Each headbolt would tighten to a point .... stop.... then budge just a little more with the constant pressure. I personally believe that re-torque is a compensation for the clickers. My oppinion is partially personal exp. and partial advice from a trusted machinist.

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