How many foot pounds of torque for a high compression CNC head?

[Aikaru]

How many foot pounds should I torque my high compression head?

 

[Aikaru]

Approximately 45 degrees from 120 should be real close to 145

So from 0 to 2?

 

[Aikaru]

I was told by BikeBerry with the aluminum case and 8mm bolts no more than 140in lbs. Also in my experience turning wrenches, that last little grunt you put on it usually breaks something. In this case it would be the crank case. Trust your torque wrench. 140 is fine. Or 12lbs depending on the wrench. And make sure you check the torque after a few warm up/ cool down cycles as aluminum isn’t exactly the strongest metal and if you bought a “kit” motor, then you already know the Chinese head bolts leave much to be desired. Loctite is your friend here.

I bought steel replacements for the stock cylinder bolts. Ironically my entire kit came with steel bolts for basically everything except for the magneto cover bolts. I had two bolts on the magneto cover strip because they were so soft (Fortunately it happened at two different times so I was able to basically spin the cover off.

 

[Shawnandkate8]

So from 0 to 2?

I agree if one full rotation is 120in lbs then that divided by 4 should give you 30 in lbs. so 120 plus 30=150. Right in the ball park of everything I’ve been told. If 0 is 0 and 1 is 120, set it to 1.25 or 1 and a quarter turn.

 

[Frogslayer]

So from 0 to 2?

From noon to 1:30

 

[Frogslayer]

From noon to 1:30

2 will be fine as well

 

[Karl Snarl]

I haven't used a torque wrench on these in years. I just use a short rachet or wrench ( 8mm coupler nuts let the head nuts stand up high enough to use a ) and make sure they are good and snug, then do a 1/4 to half turn more. Then I check them all with my three finger method. If I can move them with three fingers, they need to be tighter. Just takes common sense. Don't man handle it like your gf on a drunkin friday night, but don't treat it like its glass either. The torque on these engines doesnt need to be exact. If you're racing, maybe, but a couple lbs over is no big deal. An as long as you use grade 2 rod, if you do over torque you strip a stud, which is easily replaced. Now a lot of guys like b7 and that is not and engine or vibration point type rod, to brittle and breaks before it bends. An on a motor vehicle you want bend before break. Nothing like having a head blow off at you, when it could have just stretched a stud and blew a gasket instead.

 

[Street Ryderz]

How many foot pounds should I torque my high compression head?

12 ft pounds

 

[Cisco]

My CNC head was kind of finicky getting the torque right. I had to chase it around a few times in random patterns until the nuts were all torqued to 144 in/lbs. After each of the first few heat cycles, I had to chase the torque around again. Cast heads must be stiffer, because they seem to torque down easier.

 

[Shawnandkate8]

2 will be fine as well

Wait what? Lol I’m confused

 

[Aikaru]

Wait what? Lol I’m confused

on the little torque wrenches there are numbers on the bar that go in a circle from 0 to 0 with 2 through 8 in-between. 2 is about a 45 degree angle from 0