Hey guys, what up
Can anyone please explain to me how am I to read these torque instructions, for all the other bolts it just says the range of nm I should apply, but for the cylinder head bolts it comes like this and I don't know how to interpret it
Cylinder head bolt - M10: 25 + (60~65°) + (60°~65°)
Cylinder head bolt - M12: 30 + (60~65°) + (60°~65°)
also, is a needle torque wrench as good for the job as the other options? asking because is the cheapest, but it should do the trick right?
Thanks in advance
Needle type torque wrenches work but are not as accurate as click type or digital. The numbers mean -
M10: 25 + (60~65°) + (60°~65°) Torque to a reading of 25nm, then rotate the wrench another 60-65 degrees then again, rotate the wrench another 60-65 degrees. Same for the M12 bolts, except start at 30nm.
nm/1.356 = ft lbs
25 nm = approx. 18 1/2 ft lbs
30 nm = approx. 22 ft lbs
As for the degrees, think of a clock. 12 o'clock is 0 degrees, 1 o'clock is 30 degrees, 2 o'clock is 60 degrees and 3 o'clock is 90 degrees. To convert ft lbs to nm, ft lbs/.73756 = nm
cylinder head bolts use a special metal. They're not like other bolts. They are "torque-to-yield". To seat them properly, you need to stretch them out. That's why they have special instructions.
You bring them to the specified torque, and then turn them a specific amount.
The "°" symbol means "degrees", as in an angle. A circle is 360 degrees right? 60 degrees is less than a quarter turn. Follow the specification exactly if you don't want problems.
It's similar to an oil filter right? They are usually finger tight plus 3/4 of a turn.
M10, M12 etc is a simple metric size. It literally means the bolt diameter is 10mm or 12mm. (I have no idea why they don't just write it that way)
You also should know that most cylinder head bolts are one use only, you cannot use the old cylinder head bolts as they take a "stretch" and you must use new bolts, or get ARP studs and use them.