TwinTurbo.NET: Nissan 300ZX forum - Re: Lets set a few things straight
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Subject Re: Lets set a few things straight
Posted by Scott ZShack Taylor on September 13, 2017 at 4:59 PM
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In Reply To Lets set a few things straight posted by Kyle(Houston) on September 12, 2017 at 08:09 PM
Message Glad to see this info is making it's way around.
First I would like to say that I have never spoken to you personally (Kyle) and My write up was in no way aimed at you when I reference "vendors" I thought you only sold whole engines and not parts.
My reference was to CZP and Z1.
Both sold 8740 and L19.
Z1 covered their *ss by calling the kit "z1 head stud kit" and using their own part numbers.
Czp listed the arp2k part number and called them arp2k. But were selling 8740s. (Fact)
Both only started to offer arp2k AFTER my write up went public. CZP changed their part number and description promptly to cover it up. (Of course)
As per an email I received from CZP stating all the part numbers they used to make their kits stating that "all the vendors use these part #'s"
As far as doubling washers is concerned, that was told to me by Mitch at EPR. Take it for what it is worth.
I personally have always used larger ARP washers as well.

"This is a little bit of misinformation. The stud is longer but that is because it actually seats in the block deeper. If you look at the picture he posted and if you lined up where they level out in the block; you would see that they exactly the same from the block to the bottom of the threads."

How exactly does a stud seat any further into a block when they are both bottomed out when fully installed? Perhaps you are miss-understanding what I was trying to say? if you fully fully seat both studs into the block, the 8740's will be taller. The issue here is that due to the stud being taller, you will run out of threads when tightening the nut down. Once the nut starts to run off the threads, you will loose strength due to less thread engagement between the stud and the nut. TQ specs are based on stud size and the amount of thread engagement between the stud and the block and between the stud and the nut. I have the measurements and can provide you with the evidence if you need it.

"Weird....just a minute ago we were told not to back it out. Now we are???? Per ARP the stud needs to be installed hand tight. I do NOT recommend backing it out at all. I recommend installing it hand tight and leaving it alone as per the ARP instructions."

As per my many conversations with the engineers at ARP, they say to hand tighten them and then crack them back loose a hair. That is what I am trying to say. Over the years I have heard other builders say to back the studs out anywhere from a half turn to a full turn to allow for "thermal expansion" This is why I stated the correct way to install the stud as per the head engineer at ARP. Feel free to contact him. I can give you his name and number if you like. He is a great guy. :-)

"This statement is 100% false. The yield on the 8740 is about 110 ft/lbs. I have been torquing them down on my motors at 100-105 ft/lbs for 15+ years.

The VG30DE Head stud is 12mm. You can see from ARP's site that the 12mm 190,000 / 200,000 (PSI) 8740 studs can go to 112 ft/lbs and the 12mm 220,000 (PSI) ARP2000 studs can go to 125 ft/lbs"
Since you decided that my statement is false I will say you sir are completely incorrect. According to ARP you have in fact torqued those studs past yield and have rolled the threads.
Here is why. Those specs are rated only if the entire thread count is making contact in the block. When these are in the vg block, they do not make full thread contact in the block. Especially the short bolt. Again, the ARP engineer stated that at 83ft lbs, these studs are past their yield when adding in the lack of thread engagement. You can't simply look at their website instructions and base a statement on the bolts capability. These figures change on every application.
He specifically said if you are torqueing higher than 83ft lbs you have galled the threads on the stud. This means you have torqued past the yield point. Sorry

"If you are getting water in your oil, you have bigger problems"

Here is the real issue. I don't know if you have tuned or ran a car on e85 or not. But I have many, Many under my belt. It is a known fact that an engine on E85 will develop condensation in the crankcase. If you have ever ran a catch can on an E85 car, then you will know about the smelly ethanol water that keeps filling up the tank. This is why I always recommend more frequent oil changes and also why I will NEVER use L19 in a car running E85. Why risk it? Even the engineer at ARP aggressively agrees on this. Hence why they do not list it as a head stud option.

Perhaps you are confusing tensile strength and tq yield.
Tensile strength pertains to the metals breaking point.
Yield is the limit before the metal will not return to its original shape. Tq limit also refers to the point that threads will gall up or will roll over. This will render the fastener useless. According to ARP engineers, the 8740 threads will roll at 83 ftlbs. So you have compromised your hardware by torqueing any higher than that. Yes while you are referencing the tensile strength differences, that measurement is different than clamping load. Clamping load is important as it is what is initially holding the head down. The fasteners tensile strength pertains to how far the head can lift before the fastener would break. I assume you know this since you say you are already torqueing to 105. You do this because you want the head to stay put. So if you factor in the thread contact area, you must reduce the amount of tq you apply to the fastener based on the hardness of the metal and the thread engagement count. So just because L19 is capable of 125lbs in the ideal situation, that is not the case with them in the VG block.
Again, the engineers words from ARP not mine. He told me to feel free to share this information so I did. I even shared it with your machinist Joe who was very interested in the information and was unaware that the studs he was using to torque his torque plate down during boring were not arp2k. I have since supplied him with the real deal.
Just for the record, I have no hard feelings against you or your shop. I am not far from you here in Houston and would welcome a meeting with you anytime. I am sure we could swap some interesting war stories.

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