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  #31 (permalink)  
Old 04-14-2004, 02:23 AM
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well the math is the same so i guess thats what im about to say now. lets assume you thread your bolts one half inch into the intake. and you still use four bolts. the the stress in the aluminym intake will be shear stress (the threads in the hole will have to be sheared off and a cylinder of aluminium, containing the threads) will have to be pulled out of the intake by the bolts)

now for the physics part:

the diameter of the cylinder will naturally be the outer diameter if the bolt (assuming the steel bolt is stronger than the aluminum intake) well say 3/8 inch. ans the length was 1/2 inch (in reality i think everyone would use longer bolts but for sake of argument, well assume that .5 inch of thread is engaged.

so the cylinder surface area is then pi/4*(3/8)*(3/8)*.5=0.0552 square inches, lifting a 750 pound engine the stress in the aluminum, lifting only in one bolt, engaded no more than 1/2 inch is 13586 psi. or 3396psi if you shoud choose to unstall all four bolts.

there is no where on earth you can aquire aluminum with that low a yield stress. not even with large casting flaws.

again if you use 4 quality bolts and thread them atleast .5 inch into the intake (.75 inch will reduce the stress by another 50%) you will never ever have any problems.

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  #32 (permalink)  
Old 04-14-2004, 04:44 AM
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I'll still use my chain thank you.

P.S. My offer on the lift plate still stands, it's brand new.

Vince
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  #33 (permalink)  
Old 04-14-2004, 05:55 AM
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Your not getting my point...

My point is that on paper, or in an equation it looks good, but really there are too many factors against it.

Your also forgetting other factors which could instantly double those numbers for weight, a sudden drop or short drop could double the weight of that engine on that bracket, being dropped a bit and at an angle, vibration, etc...

If someone told you that a single string of this magical material that was only as thick as a hair could hold a 20 ton weight, would you stand under the weight?

It is personal opinion here man, and I dont like them and will never use them. Intakes were never designed to take that kind of stress and I'm not about to risk destroying an engine any day soon.
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  #34 (permalink)  
Old 04-14-2004, 06:26 AM
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Use the factory brackets.
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  #35 (permalink)  
Old 04-14-2004, 07:14 AM
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factory brackets? Where and what are those?

K
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  #36 (permalink)  
Old 04-15-2004, 08:59 PM
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Quote:
Your also forgetting other factors which could instantly double those numbers for weight, a sudden drop or short drop could double the weight of that engine on that bracket, being dropped a bit and at an angle, vibration, etc...
Actually, a drop of only an inch, would equal in about 10 times the amount of force. I have always used a chain or a leveler, and will never use on of those plates....
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  #37 (permalink)  
Old 04-15-2004, 09:13 PM
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Quote:
Originally posted by killerformula
factory brackets? Where and what are those?

K

When the engine was installed it had a bracket (with a hole in it) on each head. Most of them got removed for one reason or another, or they just quit leaving them on the engine.
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  #38 (permalink)  
Old 04-15-2004, 11:57 PM
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First I'd ask myself, are the threads in the aluminum perfect? Never used? If used, did they have antiseize compound on them or not? Corrosion? Cracks or surface imperfections? Never been over-tightened or forced loose when corroded? Then I'd ask myself, how much is my motor worth? The levelers are only $30 at & they do make things much easier. Especially if you grease the big threaded thing first
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  #39 (permalink)  
Old 04-16-2004, 12:01 AM
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Originally posted by 1BAD80
Use the factory brackets.
egg-jac-ory!
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  #40 (permalink)  
Old 04-16-2004, 12:21 AM
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I have pulled my 283 with a TH400 with a carb plate on an aluminum intake.
Plate was .4" thick, carb studs screwed all the way to the bottom, nuts hand tightened to as much as the nut would take before ruining the thread.

A bit of real world practice:

A good rule of thumb in my company (I'm a B.Sc. in Mechanical Engineering and we build large diesel engines for ships and power plants) is that a bolt a a minimum thread engagement of 1x bolt diameter. We prefer 1.5x diameter and design after that both in steel and cast iron.
1x is only used in tight spaces...

For aluminum thread engagement I seem to recall a figure of 2x thread diameter.

The key to a good bolt connection is good thread engagement and proper tightening.

The idea of a bolt connection is to preload the bolt to it limit, which is larger than the amount lifted or force applied to the bolt.

When doing this the connection will hold up.

When a corner breaks the intake off I guess that the threads were not properly engaged in the manifold, thereby applying a bending load on the stud, which the aluminum cannot handle.

The average European equivalent on a 3/8" bolt can be loaded to a stress of 71,000 PSI or an equivalent load of 6,300 lbs.....

Four carb bolt should not have a problem carrying the load on an engine......

I have to admit that at first I was nervous, but digging into it, I assured myself that it would work...

Just my 0.02....

Kind regards

Bjarne
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  #41 (permalink)  
Old 04-16-2004, 07:49 AM
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hej bjarne, kan det passe at der er endnu en dansk maskinengeniør her i forumet.... velkommen

and where does this math come from:
Quote:
Actually, a drop of only an inch, would equal in about 10 times the amount of force
the only thing that will increase the load is if you increase the acceleration. the load on the bolts is the mass of the engine multiplied by the gravitational acceleration. lets assume you let the engine free-fall one inch.. then to be caught by a cherry-picker. if your number if 10 times the force should hold true then you'd have to stop the engine in about 1/10 of an inch and have the engine hang perfectly still after wards (likely??). this requires one of two things: either you have an almost infinitely rigid cherry-picker made entirely of kryptonite or you have no clue what you are saying...


but as previously stated in his thread: its a tool and if you dont like it, just dont use it.

by the way: if lift plates were that unsafe to use, dont you think with the judicial system in the US, somone would have gotten a very large settlement, and no company from that day dared to produce or sell them,

Last edited by deuce_454; 04-16-2004 at 08:01 AM.
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  #42 (permalink)  
Old 04-16-2004, 08:05 AM
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ja, det må man sige?

Vi komme nok til at tale lidt sammen....PM
Vi har faktisk talt sammen før, og jeg har luret lidt på dig.
Kompetente svar.........

Sorry for the danish language guys.
Funny thing to realise there is another Dane on this board, that's just great to find a fellow Danish maniac via this board in the US......

We'll keep it in English now.....
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