DD Head Bolts

[Pete]

Looking for advice and knowledge on DD head bolts. I am getting ready to re-torque for the second time the head on my port 4-53. Had an oil leak at the rear of the head/block joint that seems to have been cured by a re-torque. Now that all the oil has been "squeezed out" the joint, I plan to retorque one more time to make up for the oil film removal. But, am wondering how I got here in the first place. I have heard that head bolts can stretch. Is there a way to identify a stretched bolt? Does it still torque to spec? Does it make sense to just replace the bolts to eliminate that possibility? And in replacing the head bolts, do you remove them one at a time without loosening all the head bolts at once, using the standard torque sequence? Thanks

Pete

 

[BUSTER]

The accepted standard for checking a headbolt for stretch is to measure it with jig or a micrometer.Most manufacturers publish the acceptable tolerances in their service manuals.Headbolts that have been overtightened may very well be stretched.If you don't have means to measure the suspected bolts,either take them to a machine shop or just replace them.

If you are trying to do this on an already runnable engine,remove the bolts one at a time and tighten the new bolts to the first stage and torque all in sequence when finished or you may compromise the integrity of the seals and gaskets. Tony

 

[Trojan]

If you really want to be accurate you need to have your torque wrench checked to a known value. The dial up snap over type wrench is not very accurate unless its celebrated every time its used. The older beam types were better, but harder to use and could be used as a known. That is how I calibrate mine. When pulling torque with a snap over wrench the slower you pull it the more accurate it will be. If you left it in the tool box preset it is junk or way off calibration. They must be returned to zero at the end of each use to maintain any thing close to accurate. Unless you really cranked on the head bolts you most likely have not overstretched the bolts. Good luck.

BILL