Exactly how does those flimsy engine stands hold a heavy motor without the threads/bolts stripping or breaking?
That is a lot of weight hanging out there.
You would think it would be better to hold the engine at both ends....not just one end?

 

You'd be suprised at exactly how strong a bolt and its threads are. It really wouldn't be a good idea to hold the engine at both ends because a lot of work needs done on the front of the engine (timing sets, cams, harmonic balancers, ect..)

Some engine stands are dangerous though, like the 3 wheeled ones. I opt for the ones with 4 wheels, as they have better balance.

 

I junked the bolts that came with my stand and replaced everything with grade 8. I was concerned too. I also welded gusset plates where I thought I might have a problem. So far, so good.

 

I have a super-cheap, flimsy engine stand (that I bought for $5 from some lady who was using it to rebuild a Toy motor) and the bolts are the least of my worries. My concern is the crappy porous welds I see on it. The next engine I do, I'll definitely buy a nice one, but this one did support my 400 from bare-block all the way to fully built (sans accessories).

 

The only engines I have had on mine that concerned me were a fully dressed 390 with a cast iron 4BBL intake, and a 300-6. The length of the six made the stand front heavy, and I almost lost it when rolling over a bump in the concrete.

 

Thread moved to Garage and Workshop

-Matt

 

i have a cheapy $30 engine stand rated for 1000lbs, it springs around a bit while rolling the motor around but its never been unbalanced and has never worried me, works like a champ, but ive only ever had fully dressed small blocks on it

 

I have a cheap one, and I'm afraid to hang my 300 six on it. I put it on there to take it apart, and it hung way down! I put a block under the outboard end of the crank until I had the motor stripped down. It's alright w/ a small block, though.

 

We bought one a while ago...says it can hold 2,000#

After putting our International 392ci on there, it wobbled like crazy if you touched it or tried to work on it. We are using a ratchet strap hooked to a rafter, and the front of the engine to help support it while its sitting now.

 

A bolt is strong in a "shear" load condition and only if it is loaded on the "grip" length of itself.
The "threads" are where it is at it's weakest....if it is a shear bolt.
From what I have seen the weight of the engine is bearing down on the threads causing a stress riser right at that one thread.
I know machined bolts are strong but I was taught that loading on the threads is incorrect.
I'm going to look at building my own.....four wheel.....better supported. Just makes me nervous.

 

i have a cheap one rated for 1,000 lbs. i had my 390 on there and it sagged a little but never broke. all engine stands will flex. they must flex just like anything else. if there is no flex it will shear.

 

I built one for overhauling a 4 cyl. industrial diesel that weighs about 1200 lbs. fully dressed. Used 4" x 1/4" wall square tube, and a three wheel setup. Supported the engine with four 10 mm bolts into the rear ISO flange. Used the metric equivelent of grade 8 and torqued to recommended setting.

Worked great and was very stable. Only thing I didn't like was the rubber wheeled casters. I'll replace with metal wheeled casters before it is used again - they roll easier (on a clean floor anyway!).

One nice thing about the four wheeled stands, besides the added stability is that you can easily put a drip pan under the stand when dissassembling the engine.

 

As far as the bolts are concerned: The bolts have to be the correct length for the job so that they can be torqued down, creating a lot of friction between the fixture and the engine. That friction adds a great deal to the overall holding power.

Think of the bolt as a very strong spring. When you torque the bolt properly you are actually stretching it within it's elastic limits. The tension pulls the two surfaces together so there is no slippage between the two and the bolt cannot shear because of the friction between the block and the fixture.

The bolts should go into the threaded hole at least one and a half times it's diameter.

When you use a hardened bolt you should also use a hardened washer for your torque reading to be correct.

 

I have a Matco 4 wheel stand with the geared mounting head. It sure makes turning the engine around easy.

 

I have a 1000# stand with a 300 6 FI fully dressed and had no probs. I also put a 392cid IH motor on this same stand and watched it sag a mile.