Torque on Stainless Intake Bolts?
Thread Starter
Instructor
Joined: May 2011
Posts: 103
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From: Lithia FL
Torque on Stainless Intake Bolts?
Guys: I just got my intake back from being ported and am excited to install it. I went ahead and got stainless intake bolts all over the intake as well. I bought the entire kit from Alloyboltz.com and it was quite reasonable. I must recommend them. Anyway, they provided an info sheet about their bolts and recommend anti-sieze on all bolts, which I would have done anyway. But...they recommend backing off the torque values by about a third due to the anti-sieze. The intake bolts are M8 X 1.25 (I believe) and they recommend torquing them to 10.7 Foot Pounds. Does this sound correct? Is 10.7 foot pounds fine for the intake, given that I will be using anti-sieze? Also, none of my bolts go into the water jackets so I don't need to seal any of my intake bolts, right? L1986 with AL heads. I appreciate your thoughts.
Race Director
Joined: Apr 2003
Posts: 17,700
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From: moraga ca
I torque my intake bolts at 25-30ft/lbs. I use rtv on the bolts that go into the water jackets. The intake bolts that go into the heads on my L98 are standard, not metric. What year is your car?
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
Use a little star washer or something similar or they will loosen up with a few heat cycles dont wanna have to pull those runners unless you have to. May want to double check them at least once after running it a few times at least on the base anyway
Thread Starter
Instructor
Joined: May 2011
Posts: 103
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From: Lithia FL
Intake bolts
My car is 1986 with the aluminum heads. Maybe the intake bolts are sae. They thread in correctly. So now my chart says 18 foot pounds for the 3/8 bolts. I double-checked and none of my bolts enter the water jackets at all. One will go into the valley and the other stops before it goes into the coolant passage. This is the same for the 4 corner coolant passages. Do I really need to seal them with anything?
Last edited by ChasD; Sep 30, 2012 at 11:59 PM.
Thread Starter
Instructor
Joined: May 2011
Posts: 103
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From: Lithia FL
washers
I went with the standard allen heads...not the button heads. Anyway, I have the correct washers for the bolts everywhere on the intake. Yes...I do not want to take this things apart again. I plan to torque them and re-torque them at least 24 hours later. So should I go with the full 25-30 pounds of torque even with the anti-sieze?
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
I thought the FSM calls for something in the 33-35lb range. I'll bet 25-30 is enough...not sure about 10.7 tho.
I did mine at 33. To be honest, I started getting nervous above 30. (stripping threads)
I used teflon paste -- to serve as a sealer and release agent.
I did mine at 33. To be honest, I started getting nervous above 30. (stripping threads)
I used teflon paste -- to serve as a sealer and release agent.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Great advice. Compress that intake gasket evenly. Tighten from the center outward. (Do the center four then spread outward)
I did mine to 20, 25, 30, then 33.
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Thread Starter
Instructor
Joined: May 2011
Posts: 103
Likes: 0
From: Lithia FL
Thanks!
Guys: I appreciate your help. I will use the FSM for the order on torquing and go in stages. Similar to torquing head bolts. In a pattern and stepped through torque values. I was just not sure about why they recommended that I use less torque with stainless fasteners where you MUST use anti-sieze.
Burning Brakes
Joined: Dec 2008
Posts: 1,021
Likes: 7
From: Morgan Hill and Marina California
When the bolt is lubricated, you get the same tension with less torque
because the torque doesn't have to fight friction. In really serious
applications, they measure the bolt stretch.
Chuck
because the torque doesn't have to fight friction. In really serious
applications, they measure the bolt stretch.
Chuck
Instructor
Joined: Mar 2010
Posts: 216
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From: Shrub Oak NY
The torque specs come from someone test torquing the bolt while measuring its length until it stretches something like 4%. The same bolt installed in say a head where the length of the bolt can't be measured is torqued to the same value and should have the same stretch if the threads are in good shape and properly lubed. The bolt is actually elastic and acts like a rubber band, staying tight without a lock nut because of the stretch. If a bolt is over torqued enough the structure of the metal will change, making the bolt no longer elastic and able to keep itself from coming loose. The bolt will also be weaker. I wonder about stainless, if it is elastic enough do that. Maybe it depends on the alloy.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
The reason you need to Coat stainless steal with Anti Sieze or Teflon Tape, is because it likes to transfer metal under high friction loads....Very bad!