Homerandabe69
05-14-2013, 09:45 PM
I am in the process of putting my engine together and I am having trouble finding the correct stretch for my rod bolts. I am running the SCAT #2ICR-6000-7/16 kit that has 6" I-beams with ARP 8740 7/16" cap bolts.
I have been doing all kinds of searching on the internet and can't find a specific stretch value for these specific bolts in this kit. I would look at the instructions that came with it but the machine shop that did my balancing apparently decided to keep them.
I have found a few discussions and the best I have come up with is either 64 ft-lbs with 0.0046" stretch or 63 ft-lbs with 0.0050"-0.0055" stretch. I would be comfortable just going with the second range to make sure I had plenty of stretch except that with the ARP lube I am getting to 0.0046" stretch at about 83 ft-lbs. To get to 0.0050" I would be at around 95 ft-lbs of torque on each bolt which is way over the maximum recommended amount. I have read that the new ARP lube is actually quite low in lubricity compared to their old formula and it increases the torque value for the corresponding stretch over the recommended amount. Even so, 20 ft-lbs extra is a lot of torque.
I have tried calling ARP but they redirected me to SCAT saying that they make their own torque/stretch values for their kits. I called SCAT and they told me not to worry about the stretch and just torque it to 58 ft-lbs. I don't want to throw my rods through my block so I this is not an acceptable answer.
If anyone has this kit and can let me know what the info in the instructions says that would be great. Otherwise any input from knowledgeable people would be great too. I am going to leave it torqued to 0.0046" if I can't get any good answers. Thanks.
I have been doing all kinds of searching on the internet and can't find a specific stretch value for these specific bolts in this kit. I would look at the instructions that came with it but the machine shop that did my balancing apparently decided to keep them.
I have found a few discussions and the best I have come up with is either 64 ft-lbs with 0.0046" stretch or 63 ft-lbs with 0.0050"-0.0055" stretch. I would be comfortable just going with the second range to make sure I had plenty of stretch except that with the ARP lube I am getting to 0.0046" stretch at about 83 ft-lbs. To get to 0.0050" I would be at around 95 ft-lbs of torque on each bolt which is way over the maximum recommended amount. I have read that the new ARP lube is actually quite low in lubricity compared to their old formula and it increases the torque value for the corresponding stretch over the recommended amount. Even so, 20 ft-lbs extra is a lot of torque.
I have tried calling ARP but they redirected me to SCAT saying that they make their own torque/stretch values for their kits. I called SCAT and they told me not to worry about the stretch and just torque it to 58 ft-lbs. I don't want to throw my rods through my block so I this is not an acceptable answer.
If anyone has this kit and can let me know what the info in the instructions says that would be great. Otherwise any input from knowledgeable people would be great too. I am going to leave it torqued to 0.0046" if I can't get any good answers. Thanks.