AZGhost623 Posted May 27, 2013 Share Posted May 27, 2013 Snapped two head bolts putting my head back on. Its a P90A head, that was shaved .080. It was shaved prior to it coming off, and Im just reusing the existing bolts. Torquing them down to 60 ft lbs per spec. I find it very unusual that they snapped. Granted they were used, and put through what unknown conditions, is it possible that they were just worn? They do not look like they have been modified or cut shorter for the modified head. Is this needed? I ordered a brand new set from MSA today, so I can try again next weekend. Maybe an extra washer to raise them up a bit incase its bottoming out causing the snap? I did blow out the holes with some compressed air as well. Suggestions? Quote Link to comment Share on other sites More sharing options...
78zstyle Posted May 27, 2013 Share Posted May 27, 2013 As far as I know you aren't supposed to reuse stock headbolts as they stretch out. Quote Link to comment Share on other sites More sharing options...
dexter72 Posted May 27, 2013 Share Posted May 27, 2013 I would also run a tap down the threaded holes to make sure the threads are clean. Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 28, 2013 Share Posted May 28, 2013 L-series headbolts are fully reusable after inspection. Good luck trying to buy new ones, at any rate. Old bolts harden and snap. Did you inspect the bolts for necking, stretching or other damage before trying to re-install them? Were the threads oiled as called out in the assembly manual? Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 28, 2013 Share Posted May 28, 2013 (edited) Anti-seize used instead of oil? Less friction = more tension for the same torque value. Thinking outside the usual, if one was planning to re-use head bolts shouldn't they measure the torque required to remove them? They can be over-torqued and stressed past yield point on the way out also. Not stretched but twisted. Just thinking... Edited May 28, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted May 28, 2013 Share Posted May 28, 2013 I usually run a tap down the holes.Then clean with brake parts cleaner and compressed air.If any of the shank(unthreaded section) of the bolts have rust pits they are trash-thats where they will snap.Alot of modern engines have torque to yield bolts that are not reusable.The arp head stud set isnt that expensive from Summit Racing-About $120-$150.That seems like alot but you have to consider if you want to do the job perfect the 1st time or end up doing the job over 2 weeks later. Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted May 28, 2013 Author Share Posted May 28, 2013 Ordered from MSA a complete set for 90$. It shows they were instock, so hopefully they have it. Won't know until tomorrow if they call me to say they don't have it. Ill look into the ARP's if thats the case. Used anti-seize on all of em when I put them back in. After inspecting some, some are definitely pitted. Now that you mention it, they might have been over torqued. I had to use a breaker bar to get them out. Where as when I torqued them in at 60lbs they were still relatively easy to get out without the need for a breaker bar. It was a rebuilt engine out of CA with less than 50 miles on it so they weren't seized into the block. Ill never be buying stuff from this guy again... On a side note, there seems to be two flavors of head gaskets with Felpros, 21157PT1 and 8799PT. Anyone know the difference other than price? Quote Link to comment Share on other sites More sharing options...
duragg Posted May 28, 2013 Share Posted May 28, 2013 8799PT seems to indicate for an L28e motor The 21157PT1 for a plain L28. For guys like us with Hybrid assemblies it may not matter (L28 block / L28e head). Order them both from Orielly, compare, return one and report back! Sorry about the hassles. Doc will get it running. If the vendor that did all this is indeed a bad player, then you are being too nice by not calling it by name Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 28, 2013 Share Posted May 28, 2013 What is being stated here? Change the coefficient of friction by altering the lubricant used and then just wing it without calculation of the new proper torque? You put MOLYKOTE on a fastener specified for SAE 30wt motor oil and torque it to the same indicated torque value...things will stretch or break! "Anti-Seize" means many different things to different people... To some, it means MOLYKOTE, to others, Fel-Pro C5-A or equivalent... Each with QUITE different effects on take up on a bolt and final tensile loading due to changes in thread and under head friction. A very small change in friction can result in tensile overloading by a factor of 300%, easily! Don't start changing lubes without knowing what you are really affecting! Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted May 28, 2013 Author Share Posted May 28, 2013 (edited) Hey Tony, How do you calculate the new required torque when you use anti-seize? Apparently I have been doing it wrong my whole life if thats the case. Apply anti-seize and torque to spec. Should I just account for 1-5 less ft lbs when torquing it? Edited May 28, 2013 by AZGhost623 Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted May 28, 2013 Author Share Posted May 28, 2013 8799PT seems to indicate for an L28e motor The 21157PT1 for a plain L28. For guys like us with Hybrid assemblies it may not matter (L28 block / L28e head). Order them both from Orielly, compare, return one and report back! Sorry about the hassles. Doc will get it running. If the vendor that did all this is indeed a bad player, then you are being too nice by not calling it by name Yeah, this "vendor" did a lot of things which I dont know why he did. When I called him out on it, its all apart of his secret sauce. Its my impression that the bolts got reused (definately not new) and possibly over torqued. After the second one snapped I inspected them all and some were pitted and "rough" rather than a smooth bolt. There were two spacers under all the springs, cam was retarded quite a bit for TDC. Some of the valves were not the same lengths as others and some of the springs were very worn to the point it wasnt safe using them according to the machinist. It was an extremely poor build, I guess thats what you get for 2800$ shortcuts.... In one way I am glad I had problems to find these things and get them corrected. now. When the rockers all fell off that day I should have pulled the head and had someone go through it to make sure it was all ok. I hope to have this all put back together this weekend if MSA has the parts. I think I may only torque to 55-57ft lbs to be safe since Tony's comments above saying lubrication aftects the final torque down. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 28, 2013 Share Posted May 28, 2013 Hey Tony, How do you calculate the new required torque when you use anti-seize? Apparently I have been doing it wrong my whole life if thats the case. Apply anti-seize and torque to spec. Should I just account for 1-5 less ft lbs when torquing it? Go to the "bolt science" website and take a look... There is a formula that takes into account lubricant coefficient of friction. The small change on the lubricant can make a HUGE difference in tensile loading. Paraphrasing what is at "Bolt Science": Under head friction is 75% of turning torque, Thread Friction, 15%, and Tensile Stretch 10%. These are rough estimates, but "the pie still has to add to 100%" Burnish the threads of the bolt and nut, and you get 5% on the threads now, still with 85% under head friction, meaning 15% of the torque is now devoted to tensile elongation. If properly designed joint with a fastener around 75-80% of yield at clamping...what margin is there before that bolt goes plastic and deforms...loosening the joint, leading to fatigue cycling, fretting, failure? Change lubricant, and you DRASTICALLY affect the thread and under head friction... Drop that under head to only 75% for example, and those threads down to near 2% (like MOLYKOTE likes to do...) and where does that pie equation sit or tensile loading on the bolt? 200%+ increase? They show the formula there, and give some common lubricant coefficients, so you can recalculate he indicated torque you should shoot for with the new lube. It's a very good primer on fasteners and joint design. When you go there, be sure to watch their "Junkers Machine" video and see what lock washers really do for you! Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 28, 2013 Share Posted May 28, 2013 I think I may only torque to 55-57ft lbs to be safe since Tony's comments above saying lubrication aftects the final torque down. Don't incorrectly torque fasteners attributing it to me! I don't say lubrication affects the torque used, EVERY engineering text and design criteria for a bolted joint says it! The torque is to give a specific preload to he fastener. An assembly procedure will state "clean, dry threads" or "lubricate with XXX" Just follow the instructions. If the bolts break, it's because they were over stressed. If you torqued them past their recommended value, that did it. If they were corroded, that did it. If it was both, THAT did it! Fact of the matter was you were re-using expendable items (see note above about "burnishing the threads" to see why they are noted as expendable.) Most critical fasteners are specified for one use simply because father dramatic effect of thread burnishing can present. New threads unburnished give repeatable results for which engineers can specify procedures. Start re-using things and tightening it PROPERLY becomes much more complex! Quote Link to comment Share on other sites More sharing options...
duragg Posted May 28, 2013 Share Posted May 28, 2013 Man I got lucky... Quote Link to comment Share on other sites More sharing options...
cgsheen Posted May 28, 2013 Share Posted May 28, 2013 I was thinking along the same path as Tony - the Factory torque values are only going to be correct if you're doing the assembly exactly the way the FSM specifies. Change something, and how are you going to calculate what the "new" torque spec should be... That's why I just follow the FSM precisely in matters such as these - I'm not smart enough to figure out what any change would do to the specs. Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted May 28, 2013 Author Share Posted May 28, 2013 (edited) Man I got lucky... Yanked.jpg Alright I am game... holy crap, i got you beat by a mile... yeah these are done. Verified with MSA they are in stock and should ship today. Ill have them before the weekend. Learned something new today. Thanks Tony! Edited May 29, 2013 by AZGhost623 Quote Link to comment Share on other sites More sharing options...
duragg Posted May 29, 2013 Share Posted May 29, 2013 Glad you are making process amigo. Look forward to doing some driving with you soon. You don't need to tell you wife about this since it is technically just a "Repair" and not a "New Purchase". Glad to help Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted May 29, 2013 Author Share Posted May 29, 2013 LOL - She knows.... and her exact response was "you should have put a V8 in it" which is saying something because she likes to keep things in the same era. Its all good... hopefully this car doesnt continue its curse much longer. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 29, 2013 Share Posted May 29, 2013 Man I got lucky... Yanked.jpg THERE YOU GO!!!! Quote Link to comment Share on other sites More sharing options...
NorwegianZED Posted May 30, 2013 Share Posted May 30, 2013 (edited) Oops, wrong thread Edited May 30, 2013 by NorwegianZED Quote Link to comment Share on other sites More sharing options...
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