Are these 3 1/2" bolts long enough to use on an engine stand for my 350? Would 4" bolts be too long?

Also, the bolt hole is very big compared to the bolt itself and wobbles around. Do I need some sort of 'bushing sleeve' to be on the safe side? I have a 2000lb stand from this place. tx.

 

Now I'm going off memory here, but that looks like about the same amount of thread that is currently holding my 455 to its (bouncy) engine stand, so I would think it would be fine for a 350. My bolts are just shy of flush with the exiting side of the bolt hole.

However, bolts are cheap insurance if its going to be on the stand a long time. If the bolts truly worry you just get the next length up and use more washers between the bolt head and the back of the stand arms to get a few threads to poke through.

The smaller diameter of the bolts vs the tube didn't seem to matter since my washers were bigger than the arm tube. Once the bolt binds at whatever angle its going to bind at, I think its mostly a pulling force exerted on the bolt.

Be sure those are Grade 8 bolts though not just gold di-chromate plated.

Others may have more valuable opinions, but thats my take.

 

I Always use longer bolt and keep a stash of fender washers for shimming works great, I also use grade 8 bolts, The are holding a tremendous amount of weight and you do not want them failing on you.

Just my 2 cents

 

Thx. I will get some 4" gr88 bolts instead. Lucky for me, the place for bolts/washers etc. in the city, is right around the corner, about a 5 minute walk

 

grade 8 is fine but i prefer grade 5. grade 8 will sheer more easily than 5.

the length of your bolts look fine.

 

I believe you will find that grade 8 is stronger all around than grade 5. use "new" bolts not 40 year old stuff laying around.

 

i am a little off topic but i should be more clear on what i was saying about grade 8 bolts. the bolt is stronger but the threads in the block are never going to hold what a correctly torqued grade 8 bolt requires. the sheer strength is reduced when it is not at the proper torque for the bolt. that being said, you will still not have trouble with grade 8 bolts in the engine stand.

 

I'm sorry, but that is completely incorrect. Grade 8 bolts have higher tensile strength AND higher shear strength. You might want to consult a Mark's Handbook. Ultimate tensile strength for Grade 5 bolts is 120,000 psi, for Grade 8 it is 150,000 psi. Shear strength for Grade 5 is 75,000 psi and for Grade 8 is 91,000 psi. ALWAYS use Grade 8 bolts to attach your block to an engine stand.

As for length, so long as the bolts are engaged in the block threads by at least two bolt diameters (or in the case of through holes, the bolts are fully threaded and extend out the other side) then you're fine. Do not put washers or spacers between the engine stand and the block. Any required spacers or washers should be between the head of the bolt and the engine stand. The slop between the bolt and the tube on the engine stand is not desirable, but is acceptable so long as the bolts are properly torqued.

 

Keep in mind that bolt torque tables assume a cyclical load that results in gapping. That's really not going to happen on an engine stand. More to the point, the large clearance between the bolt and the tubes on the head of the engine stand result in bolt bending, not shear. You will only see shear failures if both bolt holes are tightly toleranced to the bolt diameter. Again, the higher yield and ultimate strength of the Grade 8 bolts will avoid problems here.

 

What should they be torqued to?

sloppy...

 

I don't torque them but tighten to around 30 ft lb. I don't like to put more than a short block on the 2000 lb stand I have. I also made a support that is shaped like and inverted T, going to the two legs of the engine stand and up to the front of the block, giving it support there.