how important is it to torque down the head bolts or nuts?
by: ricktheslickster - May 30, 2019 22:01:14 GMT -6
Post by ricktheslickster on May 30, 2019 22:01:14 GMT -6
My nephew and I are in an argument because after he had taken the head off a brand new engine, we can no longer get it to fire. Today after he and i were adjusting his timing, I noticed that he did not torque down the rocker arm nuts with a torque wrench, he only used the impact driver. This impact driver is one of the weakest impacts made rated at 72 Ft-lbs. It's a Dewalt, but the smallest of the family using a 12v battery. It's a DCF-815. and I would imagine that's with a full battery. I doubt very seriously that the impact driver is strong enough to torque down those nuits. when checking the chart, the value is 15 ft-bls, and this impact driver is rated at much higher than that at 72 ft-bls. So my questions are these
1) if the nuits are not torqued down to factory specs, is it possible that the compression stroke will not achieve the ideal compression due to pressure escaping thru the two surfaces between the cylinder and head?
2) and if an impact driver (not impact wrench mind you) that is rated at 72 Ft-lbs be strong enough to torque down the nuts to 15 ft-lbs?
I was there today when he used the impact driver, and there was hardly any pressure or torque applied to those nuts, that I could tell, by watching him. I would imagine that at even 15 ft-lbs, there's some actual force being applied via the hands and arms of the person who's applying the torque, and that, even with a long torque wrench that does most of the job for you via leverage. I doubt that this little impact driver was applying that same amount of torque. My nephew believes it is enough torque, and thinks I'm barking up the wrong tree by thinking that if we just torque down the nuts with a torque wrench that it may allow the cylinder to build-up much more PSI to fire the engine. Which one of us are correct, please help.
1) if the nuits are not torqued down to factory specs, is it possible that the compression stroke will not achieve the ideal compression due to pressure escaping thru the two surfaces between the cylinder and head?
2) and if an impact driver (not impact wrench mind you) that is rated at 72 Ft-lbs be strong enough to torque down the nuts to 15 ft-lbs?
I was there today when he used the impact driver, and there was hardly any pressure or torque applied to those nuts, that I could tell, by watching him. I would imagine that at even 15 ft-lbs, there's some actual force being applied via the hands and arms of the person who's applying the torque, and that, even with a long torque wrench that does most of the job for you via leverage. I doubt that this little impact driver was applying that same amount of torque. My nephew believes it is enough torque, and thinks I'm barking up the wrong tree by thinking that if we just torque down the nuts with a torque wrench that it may allow the cylinder to build-up much more PSI to fire the engine. Which one of us are correct, please help.
