Rod bolt stretch Problems
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- Опубліковано 24 лют 2013
- Some issues with the Clevite bearings and can't believe the bolts would be so different in length when they leave the factory?? I'll update in the comments what i find out when i talk to Scat tomorrow.
- Авто та транспорт
Thanks for the quick reply! The largest variance from the smallest to the largest rod bolt was .005 which seems like a significant difference but I guess this is normal. Thanks again for the quick reply!
+Kim Lee That was exactly what originally happened with me and started my confusion, i'm still learning but lots of conflicting info out there. Good luck with your build!! Cheers, Sam.
Nice catch on the rod bearing fitment! As for the rod bolts, I have to assume they were very close in length from the factory so if they have stretched that far I would replace them all. I think it would be wrong to match them up in length because presumably they have stretched (weakened) beyond their useful limit.
Buy another gauge and mark A and b bolt zero the gauge for each bolt.......problem solved!!!!
Or make a sheet snd use the tag. Zero "a" side and then tag the "b" side
Thanks, its just scary them being this far off! Ill update when i get the new bolts in the mail.
Interesting, i am having the EXACT SAME ISSUE with Eagle/ARP bolts.
What if you measure at the shoulder of the washer head and end of threads
yeah i've wondered how much the Scat brand ARP bolts go through the same QC process as regular arp bolts.
Hi Swilling - I am experiencing the same with my ARP rod bolts (Eagle Rods). did you measure your new ARP bolts and were they within .001" as ARP service rep indicated?
+Kim Lee Hey Kim, the new ones at resting length were also all over the place. I had lots of people telling me different things, in the end i ended up just treating each bolt as its own. From now on i just thread the rod bolt in by hand. Then set my stretch gauge to zero, then start torquing from there. The last ones i did recently on a friends motor, i had a torque wrench handy, and also just for kicks, used a torque wrench after tightening the rod bolts to the specified stretch, and according to the torque wrench they were all within 1-2 lbs of each other. So from now on i'll just be setting my gauge to zero once the bolt is in the rod, then tightening to stretch spec for the rods. I still seem to hear different things from everyone i talk to.. and anyone i ask certainly knows more than me. Good luck!
yep I would get some new different brand bearings and cap bolts for sure.
You torque each one individually zeroing the gauge for each bolt. Whats the issue?
yep totally right. I got thrown on a wild goosechase originally by ARP over the phone telling me what spec they should fall within before, that just confused me and since then i realized that it really does not matter because now that i understand the concept its just consider each bolt Zero, and then go from there. Simple now that i look back on it, but was really confused when people were telling me different stuff. Shoulda just went with common sense. Appreciate you checking it out.
So what was the final verdict on the rod bearings?
i tried a few other bearing halfs and found one that fit perfectly. I sure wouldnt have expected it to work that way, but it did. Cheers
Even for balancing that would throw everything off as well.
Yeah after looking at all of them and talking to ARP and the fact they say they manufacture bolts to .001 i ordered a complete new set. Scat were not very helpful even though i ordered the bolts from them. In one phonecall one guy told me they don't even torque the bolts at the facility, and in the next phonecall a different guy told me they torque the bolts then hone the rods. So inconstancy has lead me to buy a "new" set and measure them all before they have ever been installed.
Scat and eagle have arp make them bolts to Their own specs to work in their own rods. Theyre budget brands looking for budget bolt solutions to remain affordable. They might require different bolt materials and stretch specs than other brands depending on the materials they use in their rods, where that material is concentrated and how much their rods move around when tightened compared to a more expensive “beefier” set. Thats why arp is telling you its a question for scat, they dont want to tell you anything that might be wrong and ruin your rods. Scat is also being vague because this work obviously isnt being done professionally, its to avoid liability.
yep! that makes total sense, when i think about their liability is also their main concern. Great point man, thank you!
i see the problem your drinking coors beer
I put new rod bolts in every time i rebuild the engine. About 400 runs. The difference in length would bother me if they were new. Pretty sure any bolt stretched over .001 from new length should be replaced. Obviously yours are stretched well beyond their useful life.
Ha, im sure you could. it certainly is not rocket science. Just take your time. However, i would not discount a Machine shop for NOT measuring bolt stretch, especially if your not asking for it/paying for it.... its not really an issue with any kind of street engine, i'm just being picky for the sake of doing it. I'm sure i could torque these to the suggest 63 ft lbs and be fine. But i do tend to thrash my engines.
The fact that the rod bolts are longer or shorter than each other means nothing without measuring them when new. They are torqued for a specified stretch, not absolute length. I wouldn't want you working on my engine.
+Fred Thorpe You're right, my confusion was Scat telling me once the bolts have been torqued, they have a different stretch value. My worry was being my first time measuring for stretch over torque, that the reccomended stretch values would be different, since the bolts had already gone through it, when Scat torqued them to my rods. But have since learned these bolts can be re-used to the same stretch point over and over, unlike some bolts that are junkers once used. It's pretty interesting stuff. Thanks for watching.
best case cenario .. measure all of them, wrtie it down add them all together take an average and then torque the longest one till you get the proper stretch. apply the % variable from all the rods to the longest one and then move forward .. ive had this happen before .. its all offshore shit that comes from china .. arp is not exclusive to the USA.they sell this stuff all over the world then we buy back what they call acceptable,,,plus if you think your ever going to get perfect out of a box ,you can think different .. for me its a mute point .. you have the tools there in the rod stretch guage ,just use it and move forward
Great advice man, thanks. Yeah im learning more and more as time goes on how much this kinda thing is just what we have to deal with. I've learned a lot since and next build i do when i come across it, at least ill be way more prepared and less surprised. Thanks for checking it out!!
i always buy new bolts 4 a new build my bolts in my vette r ARP,,,scat/arp r a lower quarty bolt
Arp bolts aren't that great of a bolt they do break and tear up stuff