Question about torquing the heads.

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Astro

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It feels like you are twisting rubber. Goes from the constant torque increase feel to a a liquid feel where you are turning but its not tightening. When right tighty becomes right loosey is close at that point.
I see, basically almost as if you stripped it. I haven't felt that yet praise God. Man we need to get them old bolts back!
 

Hipster

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How did you discover you overstretched them?
Kinda like L31 explained it, You're pulling on the torque wrench easing up to the specified angle, you can feel the effort required increasing, then the pressure required goes down. Kind of has a "lets loose" feeling in the torque wrench. Rubbery, as L31 described it, is a pretty good analogy. At that point the fastener is junk.

I take my time and pay attention when it comes to torquing stuff down. Ham fist it together in a hurry and you might miss it even happened.
 

Astro

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Kinda like L31 explained it, You're pulling on the torque wrench easing up to the specified angle, you can feel the effort required increasing, then the pressure required goes down. Kind of has a "lets loose" feeling in the torque wrench. Rubbery, as L31 described it, is a pretty good analogy. At that point the fastener is junk.

I take my time and pay attention when it comes to torquing stuff down. Ham fist it together in a hurry and you might miss it even happened.
Yeah agreed. I had to do the drivers side head twice with a new set of bolts because I rushed through and messed it up. Made it a point to have drink, relax and take my damned time the second time haha.

Speaking of which, I was torqueing down the valve cover bolts yesterday and when I got to the final torque, I felt the rubbery feeling. A second later, the bolt snapped. I guess those were strecthed to much at some point LOL.
 

L31MaxExpress

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Yeah agreed. I had to do the drivers side head twice with a new set of bolts because I rushed through and messed it up. Made it a point to have drink, relax and take my damned time the second time haha.

Speaking of which, I was torqueing down the valve cover bolts yesterday and when I got to the final torque, I felt the rubbery feeling. A second later, the bolt snapped. I guess those were strecthed to much at some point LOL.
I have a whole list of bolts on these L31s that I do not torque. Valve cover bolts is one of them. I use a 1/4" stubby ratchet, right on the head and snug them down gradually a little at a time. When they feel snug, leave them be. I use the same approach for the cam retaining plate, the cam sprocket bolts and the lifter spider hold down bolts as well as the distributor clamp. I have seen guys try to follow the GM specs on these lightly torqued fasteners and snap them off causing themself a nightmare.
 

L31MaxExpress

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I forgot to mention too on valve cover bolts start on a center bolt, put a little tension on it, then move to the next center bolt, then move out to the end bolt, then to the other end bolt, then back to the first, move in a rotating pattern a little at a time from the center out. It draws the gasket into place more evenly and will prevent leaks. I use the nearly the same process for the oil pan bolts. On the oil pan I start with the longer outer studs. Its easier to get a nut onto the longer studs. Gradually run the nuts in until the pan starts to approach the block and gasket. When the bolts are long enough to reach, start inserting them but only finger tight. You want to get every oil pan bolt in place prior to the pan gasket being sandwhiched between the pan and the block. Once every bolt is started adequately, start from the center and lightly start snugging them. Rotating pattern from the center out. After you have light tension on the bolts, lightly snug the end nuts, then go back to the center bolts. To properly tighten the oil pan takes a solid 5-6 passes. Install it the way I describe here with silicone in the places spelled out in the OEM assembly instructions and you will not have an oil leak from the pan gasket. Do it any other way and you will.
 

HotWheelsBurban

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I forgot to mention too on valve cover bolts start on a center bolt, put a little tension on it, then move to the next center bolt, then move out to the end bolt, then to the other end bolt, then back to the first, move in a rotating pattern a little at a time from the center out. It draws the gasket into place more evenly and will prevent leaks. I use the nearly the same process for the oil pan bolts. On the oil pan I start with the longer outer studs. Its easier to get a nut onto the longer studs. Gradually run the nuts in until the pan starts to approach the block and gasket. When the bolts are long enough to reach, start inserting them but only finger tight. You want to get every oil pan bolt in place prior to the pan gasket being sandwhiched between the pan and the block. Once every bolt is started adequately, start from the center and lightly start snugging them. Rotating pattern from the center out. After you have light tension on the bolts, lightly snug the end nuts, then go back to the center bolts. To properly tighten the oil pan takes a solid 5-6 passes. Install it the way I describe here with silicone in the places spelled out in the OEM assembly instructions and you will not have an oil leak from the pan gasket. Do it any other way and you will.
Those cover and pan bolts are little ones, used to be 1/4-20, now probably 6mm. That small a bolt, doesn't take much to break it. I feel like I have average strength, and I can pull 35-40 ft.-lbs. of torque by hand, with my Husky 3/8 ratchet. I've checked it with an accurate torque wrench.... So I imagine some of y'all big guys on here, can probably pull more torque on a bolt with hand tools than me....
That's another reason those steel rails are on the oil pan flanges, to spread the clamping force out.
 

L31MaxExpress

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Those cover and pan bolts are little ones, used to be 1/4-20, now probably 6mm. That small a bolt, doesn't take much to break it. I feel like I have average strength, and I can pull 35-40 ft.-lbs. of torque by hand, with my Husky 3/8 ratchet. I've checked it with an accurate torque wrench.... So I imagine some of y'all big guys on here, can probably pull more torque on a bolt with hand tools than me....
That's another reason those steel rails are on the oil pan flanges, to spread the clamping force out.
I have built plenty of 2 piece rear main seal small blocks that did not come with the rails. Somewhere in the late 70s and early 80s GM started adding the "Corvair" rocker cover spreaders to the perimiter bolt valve covers as well. On the early stamped steel perimeter bolt valve covers it was very easy to over torque and deform them.
 

HotWheelsBurban

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I have built plenty of 2 piece rear main seal small blocks that did not come with the rails. Somewhere in the late 70s and early 80s GM started adding the "Corvair" rocker cover spreaders to the perimiter bolt valve covers as well. On the early stamped steel perimeter bolt valve covers it was very easy to over torque and deform them.
Yup! Maybe Chevy should have stayed with the 1/4"-20 stove bolts, with the straight blade heads....
 

HotWheelsBurban

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I have built plenty of 2 piece rear main seal small blocks that did not come with the rails. Somewhere in the late 70s and early 80s GM started adding the "Corvair" rocker cover spreaders to the perimiter bolt valve covers as well. On the early stamped steel perimeter bolt valve covers it was very easy to over torque and deform them.
Only pans I've pulled and reinstalled were on the '90 TBI 350 and the other '99 Vortec 5.7, so I didn't realize that all the earlier pans didn't have the rails. I think they should have... cause they do help. Just more fun to reassemble though!
 

L31MaxExpress

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Yup! Maybe Chevy should have stayed with the 1/4"-20 stove bolts, with the straight blade heads....
I found a first a while back I had not seen. I pulled the OEM 1987 TBI 305 out of the 87 G20. It had torx bit screws for valve cover bolts. It had 104K on it and by all appearences and the hardened condition of the valve cover gaskets had likely never been apart. I cannot think of another 87+ V8 I have seen with center bolt valve covers that had Torx screws holding them on.
 
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