Thread: Ever have bolt stretching when reinstalling camshaft brackets?

I was installing a '93 intake cam on my G20 and when I reinstalled the camshaft brackets almost every bolt stretched. This was on a motor that had the exhaust header stud break nearest the EGR port.

I had a spare identical motor sitting around so I used the bolts from that, no problems. I set my torque wrench correct and compared it to bolts on both heads. Seems like the bolts in this motor are weakened.

Cam's on now and working fine, at least.

Image shows a broken bolt, I did that by hand after removing. Thank goodness no bolt broke in the head, my heart stopped every time I heard the loud crack of the stretching. Each time, sounding just like a bolt breaking off in the head. Kinda like getting shot at while working.

They shouldn't be doing that, it sounds like you over-tightened. Sure your torque wrench is accurate? Every bolt stretched - says to me something was up. Maybe they were the wrong size bolts from the start from whoever did work on the engine or owned the car before you. That sounds possible because you said the spare motor bolts worked fine. Did you get the engine really really hot and then let it cool down?

I've done, um, I'd say 8 cam installs in SR20's and never once had a bolt break or make a weird sound. I've done so many that now it I pretty much know when they're tight enough w/o a torque wrench as long as I use the same wrench I've been using for other stuff for years.

Holy crap. I've done cams on numerous different car and never had an issue like this..

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Did you tighten to inch lbs or ft lbs?

+1 good call. I'm thinking his torque wrench is bad. EVERY SINGLE BOLT stretched?? That's makes no sense, UNLESS, he had the car at full operating temperature then parked it in a -10 degree freezer for the cam install. Something ain't right.

Haha that'd be funny as hell. Cam install in the freezer at walmart lmao

8 ft. lbs. Even compared the wrench to the bolts on the exhaust side, and the other head. As the bolts from the other head did not have that problem, I'm thinking that the bolts in this head have something going on. Never broke an exhaust header stud either, until this engine. Barely got it to 15 ft. lbs before it broke. I suspect heat and maybe the weird chemicals in the salts used in Philly.

I suspect a bad torque wrench. lol Ive never seen cam cap bolts do that. Then again ive never overtorqued them. I can do them by feel and get them between 80-100 inch lbs every time.

either a bad torque wrench or all threads needed to be chased and the holes cleaned out.

15 ft. lbs is twice what they should be! FYI, The only bolts that need to be that tight are the bolts for the dizzy cap.

It's also very important to torque the bolts 3 times, gradually increasing the torque in the order specified in the FSM, at the torque they specify each time. Are you using an inch lb. torque wrench? Cause if you're using a foot lb wrench, it's not going to be "sensitive" enough to follow the FSM to the letter...Ie. the first phase of the torque sequence and even the second phase.

Go to EM-29 - http://www.nicoclub.com/FSM/Sentra/1999_Sentra_SR/em.pdf

Way too much force used to tighten them down.