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Old 08-25-2011, 12:50 AM   #1
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Default Torque specs w/ARP main/rod/head hardware? And clearances?

Hey guys,

Going through and checking tolerances and I have a few questions. I am trying to find if anyone has an angle measure on ARP TTY (torque to yeild) rod bolts, first off. The tool I've always used for tty bolts is a torque wrench with an angle reading on it so that you run it xx angle past the tq spec and it gives you the proper stretch.

I'm using the following specs on my arp stuff:
Head studs : 50ft/lbs
Rod Bolts : 65ft/lbs
Main studs: 43ft/lbs

So I went with this on the rod bolts based on Sav's post, head studs also based on other peoples experiences with possibly ruining the head with too high tq, and Main stud tq is from the book. Does this sound right or is my Main stud level too low?

My bearing clearances are about .0018 (between .0015 and .0020 on plastigauge.) on my rods and .0020 on my Main bearings based on the tq numbers I used. These are a bit high, I'm sorta wondering If I should go to different bearings or stick with STD bearings that I'm using.

That's about all I have for questions. Only other thing I've messed with is re-tapping the crank pulley for no8 instead of 6 bolts. This motor actually sheared those bolts due to over-torque. Not my hand on that one.

Anyway, just some opinions would be helpful..
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Old 08-25-2011, 09:49 AM   #2
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Old 08-25-2011, 10:25 AM   #3
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I followed that, and now every time I think of it, I wonder when the head is going to crack
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Old 08-25-2011, 04:21 PM   #4
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43 sounds low for the mains, IIRC the instructions say 60 or 65. We torque the heads to 65.

For the rod bolts, what you want to do is start at 43ft.lbs or whatever, then torque through a certain number of degrees, then check the stretch. Note the stretch, then fully loosen, check stretch again to ensure that the bolt didn't yield, then torque to 43ft.lbs + a few more degrees. Repeat until you get the correct stretch number.
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Old 08-25-2011, 08:26 PM   #5
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Originally Posted by Savington View Post
43 sounds low for the mains, IIRC the instructions say 60 or 65. We torque the heads to 65.

For the rod bolts, what you want to do is start at 43ft.lbs or whatever, then torque through a certain number of degrees, then check the stretch. Note the stretch, then fully loosen, check stretch again to ensure that the bolt didn't yield, then torque to 43ft.lbs + a few more degrees. Repeat until you get the correct stretch number.
Makes sense on the mains, I don't have the ARP recomendations on me, I probably need to give them a call to verify. The 43ft lbs spec is from mazda, but I dunno it sounds quite low to me as well. I do not have a gauge to measure stretch, so it sounds as if though I'll need one. The only bolt I've dealt with like this required the use of a device that measures the angle vs tq to determine yield.
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Old 08-25-2011, 11:19 PM   #6
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Originally Posted by chance91 View Post
My bearing clearances are about .0018 (between .0015 and .0020 on plastigauge.) on my rods and .0020 on my Main bearings based on the tq numbers I used. These are a bit high, I'm sorta wondering If I should go to different bearings or stick with STD bearings that I'm using.
I'd size the mains down. Factory clearance is .0008-.0012, so you're pretty far above the factory range. ACL makes an .025mm undersize bearing which will close the clearance up by ~.001". Make sure they don't send you a .25mm undersize bearing, though.

Quote:
That's about all I have for questions. Only other thing I've messed with is re-tapping the crank pulley for no8 instead of 6 bolts. This motor actually sheared those bolts due to over-torque. Not my hand on that one.
Don't be lazy on those. You shouldn't need to upsize them if you make sure you use the OEM Grade 10 bolts and torque them correctly. Get good Grade 10 M8 bolts and make sure you torque them properly (don't use the OEM spec, since you upsized).
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Old 08-26-2011, 02:24 PM   #7
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I'll be careful with those bolts. I have the right sized torque wrenches for any fastener on this motor, thankfully. Most of my tools are more Diesel semi tractor sized, but most of it carries over to my car.

Thanks for the tips, and I did find the spec is 60ftlbs on the mains, so that's what I'm going to use.
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