How does a engine stand hold an engine?

zookeeper · Feb 17, 2004

speedy66 said:
I have seen grade 5s snap with a 6 cyclinder on the stand.. Why be cheap and risk it.. main bolts are a good idea.. grade 8 or 9 are my choice.. i believe mine are grade 8.. dont have a problem with the bolts bending.. but my ending stand bends..???

Let me see if I've got this straight, you personally had 4 grade 5 bolts in a six cylinder engine and it broke them? I certainly do not want to call you a liar, but I've had a big block chevy on a stand with 4 grade 5's and it didn't even stress them. Do you also have grade 8's holding the bellhousing on when it's in the car? There is simply no way in hell that any passenger car engine is going to stress-break 4 grade 5 bolts.

geegee · Feb 17, 2004

I used 7/16" grade 8 bolts and fender washers on an identical stand to build up a 5.0L SBF. Four bolts were used. Length of bolts was long enough to pass through stand mounts and go into block 5/8" or more. Better a bit long than too short. Use washers as spacers if you need to. My SBF was on the stand a better part of a year and did not cause problems. I rotated it on one month intervals, 0 degrees, 180 degrees, 0 degrees, etc. Be sure not to turn over once oil is in pan...I did that doofus only once!

72grande · Feb 17, 2004

geegee said:
. Four bolts were used. Length of bolts was long enough to pass through stand mounts and go into block 5/8" or more. QUOTE]

Being serious for ahlf a minute, this is probley more impotiant than grade 5 vs 8. Just be sure the bolts go as far into the block as possible.

My 351c has been on a stand for over a month with Lowes bolts.At first it was a complete engine with intake and all and now its down to almost a bare block. Forget the grade but they were just basic bolts so probley grade 5. I bought a bunch of differnt lenghts so I could find the one that would go all the way into the block and need as few washers on the head as possible.

Cliff notes version of this post: Worry about lenght more than grade.

LMan · Feb 17, 2004

I use old head bolts. No one ever said THEY were inadequate for this task.

72grande · Feb 17, 2004

gp001 said:
That's why I put up baloons, pictures of puppies, and pre-purchased tickets to Disneyland while I use it.

I would think haveing all those beutiful new parts spread across the floor would be enough.

D.Hearne · Feb 17, 2004

zookeeper said:
Let me see if I've got this straight, you personally had 4 grade 5 bolts in a six cylinder engine and it broke them? I certainly do not want to call you a liar, but I've had a big block chevy on a stand with 4 grade 5's and it didn't even stress them. Do you also have grade 8's holding the bellhousing on when it's in the car? There is simply no way in hell that any passenger car engine is going to stress-break 4 grade 5 bolts.

Grade 8's aren't required for the bell housing bolts when it's in the car., With this scenario, you have the motor ( Super Dave's gonna kill me) sittin on the mounts and the rear of the transmission sitting on it's mount. In this case the bolts have far less stress on them than when the motor ( engine) is hanging it's entire weight out into space, with nothing but the shear strength of the bolts to support it. Last year I had a completely assembled 390 hanging on those engine stand bolts. and it made me uncomfortable enough to add the engine hoist's support to ease the stress on the bolts til I put the engine into the car.

zookeeper · Feb 18, 2004

It made you uneasy simply because you do not know what the tensile strength of a grade 5 bolt, to be rated as a grade 5 bolt, anything up to 3/4 of an inch must withstand a MINIMUM tensile strength of 110,000 lbs before breaking. Now if you were to use 4 bolts, the combined minimum breaking point would be 440,000 lbs. Rest assured your killer 390 doesn't weigh that much. Where do you people get these rumors from anyway?

D.Hearne · Feb 18, 2004

Tensile strength and shear strength are two different factors in a bolt's grade rating. Tensile stregth is the force necesssary to pull it apart. Shear strength is a whole nother ball game. I'ts easier to shear a bolt than to pull it apart. When the engine stand is bent down from the weight of the motor and hanging on just the bolt threads, I makes me very leary of any bolt's quality.

zookeeper · Feb 18, 2004

Since you seem unwilling to accept facts, try this: do you really think the weak link in this chain is the bolt? How strong do you think the cast iron is that the bolt is threaded into? If you were to keep adding weight until something failed, it would be the block. That much you can bet on. Also, shear strength would only be a factor if the center of gravity (threfore the primary forces on the bolt) were at the point where the stand meets the block. Instead, the real center of gravity would likely be somewhere near the center of the cam, since the majority of the weight lies above the crankshaft of any V8 engine. Think of it as holding a baseball bat out at arms length by only the handle, is the handle pushing down or is the tip furthest from you pulling down? That is why tensile strength is the acting force, NOT shear strength. You can argue with me all day long, but the fact is, you have no real proof that grade 5 bolts are not enough to hold ANY passenger car engine, now do you?

gp001 · Feb 18, 2004

Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!

D.Hearne · Feb 18, 2004

You go right on using grade 5's and I'll keep using grade 8's or better for this purpose, and we'll both be happy. Damn why not just go ahead and use some 1/4 inch bolts? I'll bet their grade specs exceed the weight of a fully dressed motor too?

351LX · Feb 18, 2004

I have had a fully dressed 351c motor sitting on a engine stand in the garage for about a year now using the first four bolts I found in the coffee can that were long enough and had some sort of marking the head.You guys are making me nervous.

zookeeper · Feb 19, 2004

No need to be concerned. Part of a metallurgy class I took a while back was to do a tensile strength test. Our tester only went to 20,000 lbs so we had to turn a piece of steel rod down to the largest failure diameter we could. I finally got it to fail at 20,000 lbs and the diameter was less than .090 of an inch! That was mild steel 1045 rod, which is hardly stout metal. So when I see people thinking they need aerospace-quality hardware to hold a 500 lb engine on a stand, and others telling outright lies about it, I feel that maybe someone may want to know the truth about fasteners, not just rehashed BS.

351LX · Feb 19, 2004

I think if someone did an engineering analysis on it the bolt would be subject to tensile, bending and shear stresses so to calculate the size needed you would have to take all three into account.I agree an actual grade 5 bolt would be fine but I have seen bolts with 3 lines on the head that seemed to be a lesser grade.I always assumed that grade 8 bolts were more brittle than a grade 5 so the grade 5 would tend to deform before failure and a grade 8 would just snap.

akd67 · Feb 19, 2004

I used grade 8 since cost was under 3$ for 4.I keep them with the stand and dont worry about it.

crushnut · Feb 19, 2004

This is quite interesting i must say

1320stang · Feb 19, 2004

gp001 said:
Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!
Bugs: Duck Season!
Daffy: Rabbit Season!

How does a engine stand hold an engine?

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