FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Jim Comet on February 17, 2024, 07:54:08 AM
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I called Molnar to get some specs for when I reassemble my short block. In the conversation I asked about what lube to use on the ARP 2000 rod bolts that are in their rods I have. He stated that while working at Oliver they discovered that the ARP lube had a lower and lower release torque after torqueing, unbolting and then retorqueing the bolts. He state bolt stretch was always consistent but the ARP lube caused a lower release torque number. He recommended I use an EP#3 grease as it will dissolve and maintain a higher release torque. He said with ARP lube the bolts kind of smoothly glided loose when taking them apart and with the EP#3 grease they would "snap" at first when loosening them. I don't mean the bolt would snap/break, but they found they would have a much more consistent release torque. Remember, I am just a knucklehead hobbyist trying to paraphrase and pass on what I think may be good info to help others. I have built a number of motors in the past using ARP lube on their bolts and never had a failure so I assume the info I got from Molnar is geared for high end severe use race motors. If any of you use EP#3 lube for your rod bolts, do you have a recommendation? Thank, Jim
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The EP3 grease is made by CMD. It's what Molnar sends with their rods and it's what some engine block manufacturers like Dart recommend for main fasteners. It's good stuff and I keep it here in big tubes because I use a lot of Molnar rods, but IMO there are some other good lubricants as well.
I'm pretty simplistic in how I torque rod bolts, I just follow the rod manufacturer's instructions for both lubricant and torque specs. If it gives me a torque spec such as 64 lb-ft with ARP lube, then that's what I use. If it says 30 lb-ft + 60° with CMD, then that's what I do. Some aluminum rod manufacturers require just a 50W oil on the threads and under the heads. Some other rod manufacturers focus on stretch only, so you spend a lot of time with the stretch gauge.
I've also noticed that the quality of rod really doesn't affect the lubricant that's required. For instance, I just used a set of Callies Ultra rods ($2400 a set) and they just wanted ARP lube. Oliver (~$1500 a set) doesn't use CMD, they use another brand of lubricant that's colored like a robin's egg.
I personally have never noticed a difference in release torque, only the effort it takes to get a particular fastener to stretch appropriately. But I've also never used anything to measure the release torque either, which is something that the bolt manufacturers would be more inclined to do. There's a big difference between a 1.600" 7/16" 8740 bolt and a 1.600" 7/16" 2000 bolt, one takes 64 lb-ft of torque, the other will end up hitting somewhere around 85-90 lb-ft to get to the 30 lb-ft + 60° spec.
Since different lubricants can change the torque spec, I just use what they tell me to use and do what they tell me to do.
My only real advice about rod bolts is to never use an ARP L-19 bolt. They are bad news, stay away from them.
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Brent, are the L19 bolts the ones than can be damaged from the oils of your hands? Seems kinda scary considering the bolts have engine oil spraying all over them.
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I believe the L19 bolts do not like moisture - I have read hydrogen embrittlement is the issue.
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Brent, are the L19 bolts the ones than can be damaged from the oils of your hands? Seems kinda scary considering the bolts have engine oil spraying all over them.
Indeed. Hydrogen embrittlement.
I know of 3 instances right off the top of my head where the bolt heads flew off. Once on an idling engine. Twice on engines that were still on the engine stand with the rods torqued.
Avoid at all costs.
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Are these L19 rod bolts easily identified?
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Most of them are marked L19. Some of the rod manufacturers private label them, so they may be a little harder to find.
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I think the robins egg blue stuff is Lucas Extreme Pressure Synthetic Grease
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I think the robins egg blue stuff is Lucas Extreme Pressure Synthetic Grease
Yep, I believe you're right.
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I've always used ARP bolt lube and a stretch gauge. So far (knocks on synthetic material of desktop) so good.