[steviestar]

Hi guys, Ok so I have just about finished rebuilding an SR20DE. No real problems until today when I was putting the camshafts back in. The manual says tighten camshaft bracket bolts in 3 steps.
1)tighten to 1.4 ft-lb
2) then tighten to 4.3 ft-lb
3)then all the way up to between 6.7-8.7 ft-lb

The problem is my first bolt didn't even make it to 4.3 ft-lb before I felt it snap. Not the end of the world, so I tried bolt two same result.I stopped here because I'm doing something wrong.

I got the broken ends of bolts out of the head, but need someone who has the answers to tell me what the issues are.

What is causing these bolts to fail?

They're not even making to half the required torque,and there are 22 of these suckers to tighten up.

Did I put the wrong lenght bolt in the wrong hole?.

If someone could tell me is it the shortest bolts on the inside row and the longer bolts on the outside row?.

I hope all this makes sense.

Thanks for your input.

 

[CoZZm0]

Did you do all bolts in 3 steps though?

You need to tighten all the bolts working from the centre outwards in each step of the toque (i usually just do 2 steps though) or else if you try and do one bolt up it will be (essentially) trying to pull a whole lot more force down from the whole cam and that just won't work.

also you should have taken VERY careful note of where the bolts and each of the cam caps came from.

 

[steviestar]

yes, I got right through step one. All up to 1.4 ft-lb.
Started on step two, tighten up to 4.3 ft-lb. First bolt snapped, then the second. This is were I stopped to ask for help.

I have torqued every bolt on this engine while rebuilding, and haven't stripped or broken a bolt before this.

The cam caps were all marked and went back in their positions but i didn't even think to worry about the bolt positions.

I find it hard to believe this could cause the bolt to snap because it came from position 4 but I used it in position 6.

These bolts should be able to tollerate not going back to their original position. I know I should have kept them with their caps, but I'm past that and need a solution so i can close this engine up.

I'm so close,yet so far.

 

[chriscar]

What are you using to tighten these bolts down? How is a steel bolt going to break at less than 4 foot pounds? Ain't going to happen, they're not made of silly putty.

If you don't have a 1/4" INCH-pound torque wrench, just use a 1/4" ratchet, and with very very light pressure spin the bolts down in the proper pattern, in multiple stages. Usually it takes a few rounds to seat the cam in the head, and to get each cam cap to come into contact with its seat. Once you're there you can snug them up, but don't use anything bigger than a 1/4" wrench to do it.

C

 

[Cheezit]

I read somewhere that these bolts, like the valve cover studs, are "stretch bolts" that designed to extend, which makes them susceptible to snapping if they are torqued too much.

 

[Cheezit]

The cam caps were all marked and went back in their positions but i didn't even think to worry about the bolt positions.

I am looking at my camshaft caps, and I see a symbol sequence cast into the top of the caps. The symbol resembles two dice separated by hyphen, like [# - #]. The last digit is 2 dots (like on a die).
Can someone tell me what the correct order for these caps is? I think I have mine out of their original order.