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Allis dave 
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 Topic: WD45 vs 175 head bolt torque
Posted: 05 Aug 2016 at 8:25am |
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Did a 175 have the same head bolt torque specs as a WD45? From memory a WD45 is 90lbs for the 1/2" bolts and 25lbs for the 3/8 studs.
I put 8.25 pistons in my 45 and didn't know if I need to torque the head higher to make a good seal. I'm probably overthinking this, but wondered what 175 specs were.
Edited by Allis dave - 05 Aug 2016 at 8:27am
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DrAllis
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Posted: 05 Aug 2016 at 8:27am |
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They are higher, but they are GR 8 bolts !!
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Lonn
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Posted: 05 Aug 2016 at 8:34am |
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Didn't they go from 3/8" studs to 7/16" by the time the D17 came around. I guess it's been awhile since I've been into one.
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Allis dave
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Posted: 05 Aug 2016 at 9:13am |
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So should I put in new studs and head bolts? I figured they already were grade 8's. Do you know what the torque spec was for a 175?
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Lonn
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Posted: 05 Aug 2016 at 9:38am |
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I used to know but haven't done one in several years.
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Allis dave
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Posted: 05 Aug 2016 at 9:57am |
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Did some old forum research. Looks like D17's, I'm not sure if all of them did or if there was a serial break, did switch to 7/16 studs. Torque specs seemed to be still 90 on the 1/2 70 on the 7/16.
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DrAllis
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Posted: 05 Aug 2016 at 10:49am |
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Never seen a WD-45 with Gr8 head bolts. That being said, that doesn't mean somewhere in the last 50 or 60 years that some bolts may have been upgraded by someone. Gr 5 bolts only have 3-dashes......Gr8 have 6-dashes. All D-17's always had three 7/16" bolts on the spark plug side.
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Allis dave
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Posted: 05 Aug 2016 at 11:59am |
I only assumed they were grade 8's I didn't check the grade markings when I removed them. I know this is an opinion question, but do I really need the additional torque? In one way it must, because Allis changed to bigger studs, but with switching to grade 8 fasteners it would be a guessing game by looking at grade 8 torque specs to get the same tension everywhere. I would think it'd be bad to torque the grade 8 3/8's studs too much and make the head pressure uneven. https://www.fastenal.com/content/feds/pdf/Torque-Tension%20Chart%20for%20A307%20Gr5%20Gr8%20Gr9.pdfAccording to Fastenal's torque chart a lubricated course thread grade 5 1/2 bolt should only be torqued to 57 ft lbs, grade 8, 80 lbs, grade 9 94lbs. 3/8 bolt lubricated course thread grade 5 23ft lbs, grade 8 33 lbs, grade 9 38lbs. Dry zinc plated, or plain dry can be torqued a lot more.
Edited by Allis dave - 15 Aug 2016 at 8:30am
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plummerscarin
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Posted: 05 Aug 2016 at 6:16pm |
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Checked my AC manual, 1/2" @ 90-95, 7/16 @ 70-75.
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Allis dave
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Posted: 05 Aug 2016 at 8:08pm |
Thanks Plummer. Allis engineers must've thought they needed a little more clamping power with the higher compression and rpm's.
I'm just going to torque to factory specs. 90 & 25 for a WD45. I may do more harm than good removing the studs and torquing the grade 8's higher. It'd be worse to pull the 3/8 threads out of the block.
Thanks for everyone's input.
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