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Re: Retorquing head gaskets

To: ("elliottd"), ("Bill Babcock"),
Subject: Re: Retorquing head gaskets
Date: Wed, 12 Feb 2003 09:00:44 -0500
That furtive sound you heard last night was Jack Drews slipping into New Blue's 
'bedroom' to remove all of her lockwashers.

>If you remove all the split lock washers, you must be removing about 5
>pounds.  That will increase your acceleration.
>I heard somewhere that Colin Chapman fired a mechanic for using washers on
>their Lotus 7's or 11's because of the added weight.
>Don Elliott, 1958 TR3A, Montreal, Canada
>----- Original Message -----
>From: "Bill Babcock" <>
>To: <>
>Sent: Tuesday, February 11, 2003 4:08 PM
>Subject: RE: Retorquing head gaskets
>> By the way, here's some common stretch specs for ARP bolts, along with a
>> little more discussion on torque VS stretch from a website I found. The
>> angle method scares the heck out of me--I don't know why. It feels like
>> "tighten it down till it breaks and back off half a turn". I don't
>> remember the URL, I saved it as text in my Triumph resource file:
>> For any fastener to supply clamp loads high enough to keep the parts
>> bolted together, it must be stretched the proper amount. Torque does not
>> measure bolt stretch, it measures friction. This is why we prefer the
>> stretch method or the torque and angle method for tightening rod bolts.
>> To use the stretch method, measure and note the free length of each bolt
>> before tightening with a stretch gauge or a micrometer with ball end
>> attachments. Then, using the chart below, tighten the bolt until the
>> proper stretch is achieved.
>> The torque and angle method uses the lead of the thread to stretch the
>> bolt the proper amount. To use this method, simply torque the bolts the
>> amount listed in the chart below (this low amount of torque snugs up the
>> bolt and removes lash). Then, using a Snap-On #TA360 torque angle gauge,
>> turn the bolt the listed number of degrees.
>> Bolt Type Recommended Stretch Torque & Angle
>> 5/16 - Oliver/ARP 3.5 .0052" to .0057" 10 ft lbs + 55 deg
>> 3/8 - Oliver/ARP 2000 .0052" to .0057" 25 ft lbs + 50 deg
>> 3/8 - Oliver/ARP 3.5 .0057" to .0061" 25 ft lbs + 55 deg
>> 7/16 - Oliver/ARP STD (Black Bolt) .0048" to .0055" 30 ft lbs + 40 deg
>> 7/16 - Oliver/ARP WSB .0053" to .0058" 30 ft lbs + 40 deg
>> 7/16 - Oliver/ARP 3.5 .0060" to .0065" 30 ft lbs + 50 deg
>> As a final check to make sure no bolts were missed: Before bolting the oil
>> pan on, set a torque wrench at 50 ft lbs (use a wrench set at 30 ft lbs
>> for 5/16" bolts), and check all rod bolts. If any bolt turns before
>> reaching the preset torque, it has not been properly tightened. You must
>> loosen these bolts and tighten them properly.
>> -----Original Message-----
>> From: Bill Babcock
>> Sent: Tuesday, February 11, 2003 10:39 AM
>> To: 'John Wilkins';
>> Subject: RE: Retorquing head gaskets
>> I think everyone is on the right track. The complicating factor is how
>> much everything moves. These are very strange engines. We have a cast iron
>> block, steel sleeves, cast iron head, some very long and relatively short
>> bolts, none of which are through-bolts. All these things are heated
>> differently and cooled differently. Then we have a wide array of
>> gaskets--composition, copper clad, steel clad, steel shim, steel shim with
>> copper wire, and solid copper.
>> One answer for all? I doubt it.
>> I always retorque the heads--why wouldn't you? I'm not that committed a
>> spectator, so I tend to fuss around my car in the pits. If I set the
>> valves I usually torque the heads first. Every so often you find a bolt
>> that has loosened a little somehow. If you use either composite or shim
>> steel with a copper ring, you'll see a substantial change after a heat
>> cycle. Not just once--you see it six months later.
>> A bigger question is are the bolts dry or lubricated. That's a much bigger
>> variable than the heat cycle. If you torque a bolt to it's published spec
>> dry the chances of pulling out the threads or breaking the bolt are very
>> low. If you use a very effective (for sliding friction) lubricant then the
>> same torque will rip out the threads or break the bolt. I got obsessive
>> about this issue after I broke a long head bolt at the base of the thread
>> way down inside the block in the pits before the Monterey Historics.
>> Most torque specs assume a motor oil lubricated bolt. If you want to
>> really do it right, you need to find the stretch specification for each
>> bolt you are using, lubricate it with the lube you intend to use, put the
>> bolt in a fixture that will allow you to measure stretch, torque it to the
>> stretch spec and read the torque value. Then always use that lube with
>> that bolt.
>> With bigger or longer bolts, motor oil or dry torquing will give highly
>> variable numbers when you torque to a stretch spec. The torque jumps as
>> the bolt sticks and slips. The super slick stuff supplied with high
>> quality bolts is too scary to use--on a cheap bolt you'll exceed stretch
>> specs way before you see any significant torque.
>> Gear oil works okay, but I've settled on a cheap, readily available
>> anti-seize compound that I use for everything. I've also gotten allergic
>> to split lockwashers. Spending any time investigating bolt torque and
>> stretch will convince you they are a tool of Satan. Instead I have big
>> bottles of every type of locktite. I'm gradually eliminating lockwashers
>> from everything.
>> For simplicity sake I torque the long and short head bolts the same, even
>> though they really do require different torques to reach spec stretch.
>> With a shim steel gasket and copper wire rings with anti-seize on the nuts
>> and good, hard washers (no nicks on them either) 65 pounds is good. After
>> a heat cycle I remove the nuts one at a time, re-lube lightly, and
>> retorque to 65.
>> So far, so good.
>> Sounds like too much trouble, but it only took me a couple of nights to
>> make a fixture and test the bolts (I just drilled lengthwise through a 2"
>> thick chunk of steel I had, put a nut and locknut on the bottom end of the
>> bolts, and borrowed a big micrometer to measure bottom to top of the bolt
>> at five pound increments), and retorquing takes about an hour.

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