Cam Bolts!!

[87TIGN]

I am having a terrible time with this. I put the revolution x cam kit in my motor and I set up the timing. When trying to torque the cam gear down to specs (31 lbft) the bolts continue to strip. The old bolts I pulled out of the previous cam measured to be 5/16-18 so I bought some grade 8 1/2" bolts from the hardware store and put em in, I torqued 10-15-20 fine than I got to 25 and it seemed like it was slipping a bit but the wrench clicked. So I went to 31 and the bolts just spun slowly. I pulled them out to insepct the threads and on the cam they are fine. The bolt is not bottoming out on the block because you cant see the end of the bolt when it is in all the way. So I looked at the threads on the bolts themselves and they are stripped. Almost twisted the head off one. It is almost like the thread size is wrong and the threads are a hair smaller than what it needs to be. Any one have any ideas or know what the thread size should be. Maybe metric?
Thanks
Andrew

 

[noahzark]

not sure if this helps but i believe they are coarse thread and maybe the bolts you are using are fine thread?...other than that check your torque wrench again make sure its accurate...if you hve stripped the threads you may have to heli coil them...good luck.

 

[87TIGN]

They are definitley course thread. What is Heli-Coil? Is that those deals that you put in the threads of the cam and than screw your bolt in?

 

[bsbro]

check your instructions again

that sounds like a high number for a 5/16 bolt i would think more like 18 to 22 lbs

 

[87TIGN]

I bought that TR service manual from the guy that puts them on cd and it says "Timing Chain Sprocket ................................. 42(31) N.m (Lbs. Ft.)" Which is from the original service manual....

 

[gnxtc2]

Or you can be using cheap bolts. You need Grade 8 or buy some ARP bolts. The bolts that you bought from the hardware store are probably those cheap zinc plate Grade 3 or 5. The Grade 8 bolts are usually gold iradated.

Billy T.
gnxtc2@aol.com

 

[87TIGN]

These bolts are definitly grade 8 also. they are gold in color... maybe they are cheap grade 8?

 

[BlackBandit]

Easiest way to tell if a bolt is grade 8 is the markings on the head. A grade 8 should have 6 dashes on it. Also, the standard DRY torque for a grade 8 5/16 bolt is 29 ft lb's. Are you using oil on the threads? If so you will not need to torque to 31 ft lb's. FWIW I would check the head of the bolt to ensure it's grade 8, (or if it's metric it should say 10.9) then I would verify the threads in the cam sprocket are correct, make sure everything is dry, put a dab of loctite on there and torque it. You should be able to thread the bolts all the way down with you fingers. If you need any significant pressure with a wrench before that then your threads are wrong. HTH. james

 

[87TIGN]

Yeah the threads are def right cause i ran a thread chaser through and it went smoothley. I got some junk out of the threads tho which i figured would help but not so much. I can thread the bolts by finger all the way down and I even tried putting some WD-40 on the threads to see if it would help and it didnt. The bolts all have the six dashes on the heads and i am beggining to think that maybe they are a cheap grade bolt made out of crap in china or something. I have some ARP cam bolts on the way, should be here wed and I will def keep you guys posted. thanks for all your help and if you think of anything else please let me know.
-Andrew

 

[BlackBandit]

Just remember that as you lubricate the threads you will need less torque to load them up. IE: if a bolt will strip at 30 ft lb's dry it will strip at 20 some ft lb's with lube.

 

[Hot Air]

ARP stuff is definitely a step above anything you can get at the hardware store. I'm a mechanical engineer and really appreciate the quality in the ARP fasteners. It is CHEAP (well, maybe not cheap) insurance! If it is critical, use ARP!
Conrad Carter, Jr., P.E.

 

[ijames]

Hey Conrad, ever read any of Carroll Smith's stuff? Great reading. I especially liked Engineer to Win and Screw to Win (ok, ok, it's really the Nuts, Bolts, Fasteners, and Plumbing Handbook but who'd admit to reading that? ). Maybe getting a smidge dated as to vendors but the tech info is timeless, mixed in with great anecdotes from his racing career. Available at www.CarrollSmith.com -- Carroll Smith -- The Official Internet Site for Carroll Smith Books.

 

[Hot Air]

Carl,
I have not read any of his books. I do recall seeing the one about nuts and bolts at a bookstore chain. Will pick one up soon. Thanks for the tip.
Conrad

 

[87TIGN]

Conrad thank you so much for your input and I strongley agree that ARP sets the standard for excellent fastners. Also what kind of engineer are you? I am interested in pursuing an engineering degree and I think I am leaning towards Mechanical. Shoot me a PM if you dont mind.
-Andrew