can an overtightened lower intake spread/move the heads?

blk9450 said:

well see those arrows coming OUT of the block, those are the effective forces lifting the block off the head. the red arrow is the bolt force and the green arrows are the effective forces on the plane of the head. yes head bolts strech when the head lifts, although i have no idea what the force is requred to do this. the point is that more force on the intake means less force holding the heads down.


even though i have no idea where you got 12, 25 and 848,
25x12 = 300

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Jeez, a long day finishing up a engineering project takes its toll on your brain. You are right, it is 300 and that 848 should be 1280. lol. The 12 is the # of intake bolts. 25 is each torque on the intake bolt. And the 848 is each head bolt times its torque which is actually 1280(16x80).

Now in physics class your drawing would be correct but in this situation, i dont see how if you pull up on that intake, how the heads wont get wedged even more into the block. Would they not?

I dont even think this debate can be answered in full and it can not be proven. While what you say has some role in this whole picture, i doubt it plays a big enough role to make a difference.

nmcgrawj said:

Jeez, a long day finishing up a engineering project takes its toll on your brain. You are right, it is 300 and that 848 should be 1280. lol. The 12 is the # of intake bolts. 25 is each torque on the intake bolt. And the 848 is each head bolt times its torque which is actually 1280(16x80).

Now in physics class your drawing would be correct but in this situation, i dont see how if you pull up on that intake, how the heads wont get wedged even more into the block. Would they not?

I dont even think this debate can be answered in full and it can not be proven. While what you say has some role in this whole picture, i doubt it plays a big enough role to make a difference.

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well on a sbf, there are 6 intake bolts on each side and 10 head bolts per head..
so working with one head, saying you torqued the heads to 80ftlbs, thats 800 ft lbs, then intakes to 25 thats 150 at a 45 degree to the surface, intakes pull head up (away from block) 17.7 * 6 = 106.38 from the heads pulling down at 800. so thats 1/8th of the force basically of the head bolts, lost by bolting the intake down, but if you torque to 30ft-lbs, then you have 21.28*6 or 127.7 ft-lbs pulling. not much of a difference it seems, but head gaskets will blow easier when there is more torque on the intake.

heads wont get wedged into the block because the bolts are pulling away from the block. tip the drawing so that the x axis is the head/block surface and the y axis is in the direction of the head BOLTS themselves. the head bolts pull in -y, the intake bolts pull at a 45 in +x and +y direction,( first quadrant territory) this fights the head bolts, and also causes perpendicular force along the x axis. now the intake here is getting andwiched, but if you look close at the head/intake, there is nothing to stop the intake from just "riding up" between the two heads, nothing.
now there are flat sides of the intake along the y axis in my original drawing, and also surfaces right below the valve cover on the head that are parallel that would stop the "movement" of the intake from popping up if they met by creating a sandwich typer system, but they never touch. with the intake and heads bolted down, there is a 1/8"-1/4" gap. i can get pics if you want to show this cause i have a motor on a stand, or you can just look at yours. hope you can understand this jibberjabber

blk9450 said:

well on a sbf, there are 6 intake bolts on each side and 10 head bolts per head..
so working with one head, saying you torqued the heads to 80ftlbs, thats 800 ft lbs, then intakes to 25 thats 150 at a 45 degree to the surface, intakes pull head up (away from block) 17.7 * 6 = 106.38 from the heads pulling down at 800. so thats 1/8th of the force basically of the head bolts, lost by bolting the intake down, but if you torque to 30ft-lbs, then you have 21.28*6 or 127.7 ft-lbs pulling. not much of a difference it seems, but head gaskets will blow easier when there is more torque on the intake.

heads wont get wedged into the block because the bolts are pulling away from the block. tip the drawing so that the x axis is the head/block surface and the y axis is in the direction of the head BOLTS themselves. the head bolts pull in -y, the intake bolts pull at a 45 in +x and +y direction,( first quadrant territory) this fights the head bolts, and also causes perpendicular force along the x axis. now the intake here is getting andwiched, but if you look close at the head/intake, there is nothing to stop the intake from just "riding up" between the two heads, nothing.
now there are flat sides of the intake along the y axis in my original drawing, and also surfaces right below the valve cover on the head that are parallel that would stop the "movement" of the intake from popping up if they met by creating a sandwich typer system, but they never touch. with the intake and heads bolted down, there is a 1/8"-1/4" gap. i can get pics if you want to show this cause i have a motor on a stand, or you can just look at yours. hope you can understand this jibberjabber

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I was thinking there were 8 bolts per head just off the top of my head, but now that i think about it, i see the 10.

Anyway, what you say makes perfect sense and it goes write along with how forces interact. I would just like to know, if possible, at what point of "over torqueing" does it bring a weak point to the head gasket. I know u dont know this...im just thinking outloud.

to prevent it in my turbo stang, i went 100ft-lbs on the top row of bolts (actually i used studs, for more clamping force) of the heads, 90 on the bottom, and only 10 on the intake bolts, this seems the general consensus on turbomustangs.com. there is only so much force you can apply with stock or "stockish" head bolts. they are torque to yield and they stretch when you reach the torque they are supposed to be around stock specifications

more torque on the intake = less on the head gasket. there isnt a "point" where its "bad" . the head gasket doesnt get weak, but more clamping force = better, within reason, having more intake bolt torque is worse for the clamping force between the head and block. just like boobies, bigger is better but sometimes it can be too much lol

Im with blk9450 on this one. I did take physics 3, now into physics 4 (damn engineering degree ). Im really starting to think thats what messed mine up, but im getting a new engine and dont care.

yea im in physics 3 now going for mechanical engineering, but here is just the basics of statics that i took last year. where are you going to school? ill be at njit in january

IM going to Drexel University in phillly.

blk9450 said:

to prevent it in my turbo stang, i went 100ft-lbs on the top row of bolts (actually i used studs, for more clamping force) of the heads, 90 on the bottom, and only 10 on the intake bolts, this seems the general consensus on turbomustangs.com. there is only so much force you can apply with stock or "stockish" head bolts. they are torque to yield and they stretch when you reach the torque they are supposed to be around stock specifications

more torque on the intake = less on the head gasket. there isnt a "point" where its "bad" . the head gasket doesnt get weak, but more clamping force = better, within reason, having more intake bolt torque is worse for the clamping force between the head and block. just like boobies, bigger is better but sometimes it can be too much lol

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Yea i agree. I was thinking about ARP bolts anyway. I will definately keep this info in mind. I read about going tighter on the head bolts and using studs to get a better clamping force, but i never came across anyone mentioning the intake bolts problem. Thanks for explaining it, it is something i never thought about.

Im in my 3rd year of Mechanical Engineering too at the University of Michigan.

nmcgrawj said:

I would just like to know, if possible, at what point of "over torqueing" does it bring a weak point to the head gasket.

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Nobody knows. But! My guess (which is a very good one ) is nothing. Torque the intake bolts too much and what do you have? Stripped holes.

As I said before, just about EVERYTHING else is more important and more of a cause of blown headgaskets than slightly over torqued intake bolts.

Let me ask you this: Why, since bolt sides (of the intake) were tightened the same, did both headgaskets not blow? I know it's being far fetched, but this whole discussion is, too.

Look at the obvious and most important - deck surface prep. For each kind of gasket, there is a recommended "smoothness" that the deck should be in. Was it? Is the block warped (yes, headgaskets will last on a slightly warped block...I've seen it happen). Is the torque wrench accurate? From experience, I don't consider Craftsmen torque wrenches to be accurate in any sense of the word. No offense intended to anyone who uses Craftsmen tools...they just can't be pushed to the limits.

We'll even assume that, "sure, OK, the heads are being 'pulled' towards the middle of the block." At what point does the DCR (dynamic compression ratio) become too high...after all, that is what's blowing the headgaskets.

Just a few thoughts...

Joe

Joes95GT said:

Nobody knows. But! My guess (which is a very good one ) is nothing. Torque the intake bolts too much and what do you have? Stripped holes.

As I said before, just about EVERYTHING else is more important and more of a cause of blown headgaskets than slightly over torqued intake bolts.

Let me ask you this: Why, since bolt sides (of the intake) were tightened the same, did both headgaskets not blow? I know it's being far fetched, but this whole discussion is, too.

Look at the obvious and most important - deck surface prep. For each kind of gasket, there is a recommended "smoothness" that the deck should be in. Was it? Is the block warped (yes, headgaskets will last on a slightly warped block...I've seen it happen). Is the torque wrench accurate? From experience, I don't consider Craftsmen torque wrenches to be accurate in any sense of the word. No offense intended to anyone who uses Craftsmen tools...they just can't be pushed to the limits.

We'll even assume that, "sure, OK, the heads are being 'pulled' towards the middle of the block." At what point does the DCR (dynamic compression ratio) become too high...after all, that is what's blowing the headgaskets.

Just a few thoughts...

Joe

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Very good points joe. Just like that other thread on 331,347,302 comparison....too many far fetched things to actually state a FACT that can be proven.

By the way, which torque wrench do you recommend?

nmcgrawj said:

By the way, which torque wrench do you recommend?

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Let me first say that I'm lucky that I need to buy very many of my own tools since my Dad is works on cars for a living...I do have the basics though.

I bought a 1/2" Craftsman torque wrench. It have never been dropped or beaten up (that I knew of). The first time I used it was to go to 180 ft-lbs on a pinion nut. Cool, everything was fine. Put it back in it's case and never thought twice. I was torquing head-bolts and thought that it was going wayyy too easy compared to the past. Pulled out my Dad's Snap-On wrench that's 5 years old (which is used a ton and still has not needed a re-calibration) and saw that mine was out about 15 ft-lbs. That's a ton...especially for being used twice.

I really don't know much about tools other than what I hear. My Dad doesn't buy anything but Snap-On, so that's the spiel I hear from him. But, what weekend wrencher can afford a $550 1/2" Snap-On TQ. wrench? I sure as hell can't....

Joe

Joes95GT said:

Nobody knows. But! My guess (which is a very good one ) is nothing. Torque the intake bolts too much and what do you have? Stripped holes.

As I said before, just about EVERYTHING else is more important and more of a cause of blown headgaskets than slightly over torqued intake bolts.

Let me ask you this: Why, since bolt sides (of the intake) were tightened the same, did both headgaskets not blow? I know it's being far fetched, but this whole discussion is, too.

Look at the obvious and most important - deck surface prep. For each kind of gasket, there is a recommended "smoothness" that the deck should be in. Was it? Is the block warped (yes, headgaskets will last on a slightly warped block...I've seen it happen). Is the torque wrench accurate? From experience, I don't consider Craftsmen torque wrenches to be accurate in any sense of the word. No offense intended to anyone who uses Craftsmen tools...they just can't be pushed to the limits.

We'll even assume that, "sure, OK, the heads are being 'pulled' towards the middle of the block." At what point does the DCR (dynamic compression ratio) become too high...after all, that is what's blowing the headgaskets.

Just a few thoughts...

Joe

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thread title was "can an overtightened lower intake spread/move the heads? "
not "what blew my head gasket. maybe you think this thread is far fetched, but its all FACT. maybe you dont understand it, i laid it out pretty clear for us educated engineering majors, makes sense to us. i guess thats why there is liberal arts though


you said your torque wrench was off 15ft-lbs, but didnt mention at what torque this was.. it depends what torque that was at, its a percentage of the torque, not torque + 15. this shows that you dont grasp the concepts of mechanics. , that is unless your torque wrench was reading 15 at no torque, in which case you should have known that in the first place.

dcr has nothing to do with the fact that we are talking about how much effective force the torque of the intake bolts removes from the torqued heads. dcr is mostly dependent on the cam, and dcr does not directly blow head gaskets. head gaskets are blown from detonation, a byproduct of too high of a dcr, and too low of octane. this is because "Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. "
saying that dcr blows head gaskets leads to thinking that a piston just going up on the compression stroke can blow a head gasket without having fuel or spark. plus, you can run a 8:1 dcr motor on 87 octane and have detonation which causes head gasket failure, and un that same motor on 93 octane and even bump up the compression, and not have detonation and no head gasket problems.

as to the question on why one side blew a gasket... only one piston usually blows, be it warped head, bad injector causing a lean cylinder (detonation), or even bad cooling in that particular part of the head. an over torqued manifold bolt in a cylinder MAY cause the same thing. point is, manifold bolts DO take away torque from the head.

any questions?

Before this gets out of hand, like most threads do with opposing opinions, i think that the name of the thread was as stated. But i think the bigger picture is what can this lead to? Big deal if it moves the head, if it has no affect on the running condition on the motor, than it doesnt matter.

The more people say, the more this sounds just like that other thread of 302, 331, 347 comparisons. Sure valid points are made than can be proven in the physics lab or on paper. But proving it in reality is a total different story.

Both sides have made valid points, and neither can be proven IMO. The point is to torque all your bolts as close to the recommended value as possible!

blk9450 said:

thread title was "can an overtightened lower intake spread/move the heads? "
not "what blew my head gasket. maybe you think this thread is far fetched, but its all FACT. maybe you dont understand it, i laid it out pretty clear for us educated engineering majors, makes sense to us. i guess thats why there is liberal arts though

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Ha. Don't be mad because kids know how to have fun in college and still become as "successful" as things other than engineers. You really aren't the beginning or the end of anything.

blk9450 said:

you said your torque wrench was off 15ft-lbs, but didnt mention at what torque this was.. it depends what torque that was at, its a percentage of the torque, not torque + 15. this shows that you dont grasp the concepts of mechanics. , that is unless your torque wrench was reading 15 at no torque, in which case you should have known that in the first place.

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Know mechanics my ass. You feed me gibbirish out of a book while I fix your car - how's that sound. Are you really trying to argue this point? It was on a 302 - 80 ft-lbs with the type of lube I was using. Even by using your complex mathematical equations that you great engineers use, I think you can figure out that that is unacceptable. But again, I don't know mechanics.

blk9450 said:

dcr has nothing to do with the fact that we are talking about how much effective force the torque of the intake bolts removes from the torqued heads. dcr is mostly dependent on the cam, and dcr does not directly blow head gaskets. head gaskets are blown from detonation, a byproduct of too high of a dcr, and too low of octane. this is because "Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. "
saying that dcr blows head gaskets leads to thinking that a piston just going up on the compression stroke can blow a head gasket without having fuel or spark. plus, you can run a 8:1 dcr motor on 87 octane and have detonation which causes head gasket failure, and un that same motor on 93 octane and even bump up the compression, and not have detonation and no head gasket problems.

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You're feeding me this rhetoric like I don't know. You keep to your engineering ways and I'll keep to my real-world ways. And trust me, the real world ALWAYS prevails over what mathematics tells us....

And, FYI, YOU were the first to bring up the headgasket issue, not me.

blk9450 said:

its not that it MOVES the heads, but it places a static force on them. the tension causes head gaskets to blow easier because there is less force claming head to block becuase of the tension forces from the manifold blots pulling up. i dont have a link and im too lazy to look, but its common knowledge over there

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I just went along with the topic of conversation.

blk9450 said:

any questions?

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LOL. If I need help, I'll find it elsewhere. Thanks for the offer.

Joe

believe me, i will run circles around you under the hood of a car. just because i know the book, doesnt mean i dont know real world stuff. and i also would bet i have alot more stories about "having fun" too. i guarantee i can outwrench you anyday. oh yea i also have bowstaf and numchuck skills

believe me, im not saying im oh so smart, this semester i just have to get back to the books so ive been studying alot, ive failed like 8 classes and my gpa is like a 2.2, im in my 5th year, on 2nd year courses...
ive made bad decisions too