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Does anyone know what I should tighten the rod bolts on some Molnar Rods with a forged crank? They did not come with any documentation so I'm wondering if there is a sequence etc?
Ok makes sense, when I tried to seperate the new rod with my digital tq wrench, it got close to 75 ft lb before it broke loose. Son of a b**** - do I really need this stretch gauge now? :p Thanks man!
Take a sharpie and put a mark on a rod bolt in line with the cap before breaking it loose. You'll notice that when you go to torque it back your marks will line back up again. I did purchase an ARP stretch gauge as a double check and they all fell within specifications after being torqued so was it a waste of money? I say no because it gave me a double check and had it not been correct then I would've relied upon the stretch gauge in order to achieve proper bolt stretch.
Bolt stretch spec was .006-.0068 for my Molnar power adder rods, that happened to be 78-80 ft pounds with the arp lube. Recommend getting a rod vise.
this if from my 398 build thread on a different forum. I do recommend you get a digital ac delco torque adapter. it’s a great way to double check your actual torque spec. Holding the wrench, angle and so on really throws off a mechanical torque wrench. I found my snap on would be all over the place. I could count the number of times it actually matched the digital torque wrench on 1 hand. The torque wrench would click a few pounds light or not at all but I always followed the digital reading. Then I’d go back and the torque wrench would click at a different torque on the same bolt.
Last edited by jasons69chevelle; 09-26-2021 at 07:00 PM.
Thanks for that! Tom Molnar replied to my email an hour ago (wow customer service on a Sunday??!) and sent me a detailed email as well as a pdf with the instructions which I never got in the box.Btw I am using a digital torque wrench - I have a 1/2 in and a 3/8 in Kobalt (also has tq angle), which was pretty dead on when I compared it to a $nap On 1/2 in digital), so that should be ok there I hope. I guess I will have to get a stretch gauge - can't complain cos I would for hate for something like this to cause an issue later on...
Originally Posted by jasons69chevelle
Measure the stretch is the proper way.
Bolt stretch spec was .006-.0068 for my Molnar power adder rods, that happened to be 78-80 ft pounds with the arp lube. Recommend getting a rod vise.
this if from my 398 build thread on a different forum. I do recommend you get a digital ac delco torque adapter. it’s a great way to double check your actual torque spec. Holding the wrench, angle and so on really throws off a mechanical torque wrench. I found my snap on would be all over the place. I could count the number of times it actually matched the digital torque wrench on 1 hand. The torque wrench would click a few pounds light or not at all but I always followed the digital reading. Then I’d go back and the torque wrench would click at a different torque on the same bolt.
Ok so I just read the instructions he sent me. So apparently I can do the tq and angle method without the stretch OR do the stretch method?? How safe and accurate is the Tq and Angle method? As mentioned if required I can get a stretch gauge...
If you plan on torqued to a ft-lb you should get a stretch gauge and record that number for each rod bolt for reassembling on the crank. After you check your rod bore for oil clearance. However like I had stated mine came in at 75-80 fl-lbs. if you have a angle gauge already that will work if you have the required specs.
Ok so I just read the instructions he sent me. So apparently I can do the tq and angle method without the stretch OR do the stretch method?? How safe and accurate is the Tq and Angle method? As mentioned if required I can get a stretch gauge...
You don't really NEED a stretch gauge as long as you use the recommended lube and you have a torque wrench that works the way it should. Out of the two methods, torque to angle would be more accurate than torque to a ft-lb value.
If you plan on torqued to a ft-lb you should get a stretch gauge and record that number for each rod bolt for reassembling on the crank. After you check your rod bore for oil clearance. However like I had stated mine came in at 75-80 fl-lbs. if you have a angle gauge already that will work if you have the required specs.
So I should be ok using the Tq + Angle (I do have the specs for that method) or do I absolutely have to get the stretch gauge? I emailed Molnar about this as well and awaiting their response...
09-26-2021, 04:48 PM
Molnar ARP2000 Rod bolt torque? 
