Will 4 x M8 bolts be strong enough to support a car engine

[mangocrazy]

Let me explain further. I need to bolt my Lancia Beta 2 litre engine (without gearbox) to an engine stand. In the past I've bolted the engine to the stand using chunky M12 bolts into the bell housing. I now need to work on that end of the engine and the only suitable fixing points I can find are 4 x M8 threads arranged in a 70 x 38 mm rectangle (used to mount the drive shaft on).

If I use 10.9 high tensile bolts will they do the job without failing? I will be making up an intermediate plate in 12mm steel plate to bolt the plate to the engine on one side and the plate to the engine stand on the other, as the cutouts on my engine stand mounting plate don't line up with the mounting holes on the engine.

I've tried looking at tensile load and resistance tables on t'Interweb and my brain hurts. According to one search result, a 10.9 M8 bolt can hold 3,040 kg. I presume this is dead weight in a vertical orientation, not what I'm hoping to do.

 

[Munkul]

No.

Maybe if you had a larger rectangle, but as it is, the lever force on that small area will be enormous! The bolts might not fail, but the threads in the casting might!

I'd say it would hold statically, but any sort of dynamic force (even just moving the stand on rough concrete) would likely be enough to over-stress it.

You might need to make different mounting feet for your engine stand. You'd get away with a larger area and M10 bolts fine.

 

[Rrobson]

As above, although they will almost certainly support a static load, as soon as you start swinging on a breaker bar and hammering you’ll start putting a lot of stress on the bolts and subsequent threads in the engine. Don’t forget the weight will only really be on the top two fasteners but will be a bending / shearing force as apposed to a direct up and down tensile force.
Maybe try and reduce the weight if that’s your only option, can you say take the heads off first?

 

[Shiny Steve]

Put blocks / an axle stand under the sump to take some of the load?

 

[Stueeee]

As the others have said, try and get a wider spacing of fasteners from the engine stand to the motor. Shouldn't be too difficult to weld together an adapter to pick up some convenient tapped holes somewhere on your motor. Here's one I made which uses the 3/8" oil filter mounting holes and the 5/16" dynamo tapped holes on the side of a 1950s Austin motor.

 

[bricol]

If you have the late Mr. Crofts big red book, you will see many photos of twin cams mounted from the side you mention (LH from the front of the end - backside of it in the car) - but it does appear he also picks up on something higher up the block too - not having a block easily accessible, I can't suggest what

 

[Ashley Burton]

Better to be safer than sorry

 

[mangocrazy]

There aren't any other readily available mounting points that I can use, so I have to work with what I have, which is a 70 x 38mm rectangle between M8 bolt centres. Once these 4 bolts are tightened up to the correct torque they should appear as a 70 x 38mm 'block', surely? I don't buy into the assertion that only the top two bolts will take the load - it should be evenly distributed between all four bolts. That's what happens when you clamp a plate up - the load is distributed and shared. I'm not going to be swinging on breaker bars, as the engine is being reassembled, not disassembled and I'm just dressing the engine with the remaining ancillaries.

I did pose the same question to Guy Croft (sadly no longer with us), as he used these mountpoints when building engines, and his response was short and to the point, as the Facebook snip below shows. And also attached is the picture which elicited my enquiry.

 

[mangocrazy]

If you have the late Mr. Crofts big red book, you will see many photos of twin cams mounted from the side you mention (LH from the front of the end - backside of it in the car) - but it does appear he also picks up on something higher up the block too - not having a block easily accessible, I can't suggest what

I have both of his big red books but never thought to check them. Good point...

 

[CompoSimmonite]

Mount it sideways, like Stueee's post, using the engine mounting holes

 

[Munkul]

Sideways is a lot different to mounting it end on, I assumed you meant end on lol.

A lot more safety margin than originally imagined!

 

[mangocrazy]

Sorry, didn't make that clear about orientation of engine. Hopefully the photo makes that clearer - the 4 mounting holes are in the centre of the long side of the block, with the bottom 2 holes an inch or so above the block/sump interface.

 

[Kram]

So you didnt trust his advice then

Those holes seem near the bottom. Can you not weld an arm or two to your plate and add a couple more mounts, higher up?

 

[Dcal]

I'm pretty sure that bolt arrangement is use for the engine mounts on the rear wheel drive models.
It wouldn’t cost me a thought to mount it that way.

I've also got the "Big Red Book"
I got it from Guy and it was the most expensive book I have ever bought, but well worth it.

I'm sorry to hear of Guy's death.

 

[mangocrazy]

So you didnt trust his advice then

Those holes seem near the bottom. Can you not weld an arm or two to your plate and add a couple more mounts, higher up?

If something seems too convenient I mistrust it... But Guy was adamant and he knows (or knew) far more about Fiat/Lancia engines than pretty much anyone on this earth, so I'm comfortable with that. Once I've got the mounting plate to my liking I'll see if I can find any other useable mounting holes to link off to.

 

[mangocrazy]

I'm pretty sure that bolt arrangement is use for the engine mounts on the rear wheel drive models.
It wouldn’t cost me a thought to mount it that way.

I've also got the "Big Red Book"
I got it from Guy and it was the most expensive book I have ever bought, but well worth it.

I'm sorry to hear of Guy's death.

Yes, that sounds very likely. I tend to forget that the engine was originally designed for Fiat RWD cars with the engine mounted longitudinally. It was Lancia that took it and mounted it transversely (and canted it back 20 degrees.)

I'm sure you're right, and it will be well within safety limits. Guy was very hot on stuff like that so I can't see him recommending anything that wasn't up to snuff.

Yes, he leaves a massive hole in the Twin Cam community. I'm not even sure what will come of his business and if anyone else will carry it on. Big shoes to fill...

 

[cr500dom]

a single m10 cap head will take a 16 Ton sudden shock load in shear

4 M8's holding an engine will be fine

 

[Dcal]

Have you a build thread on the Beta?

I've one and a half Montecarlos waiting for their turn.
Plan is to keep one stock and maybe put modern running gear in the other (1750 TBI and a sixspeed box would be nice).
One was complete and the other a doner car but it could be made to live again

 

[bricol]

One of you needs the 2litre 16V engine in my shed . . .

I keep seeing Betas for sale . . . if I had more room under cover . . . Beta coupe has to be one of my favourite cars I've owned, closely followed by the hpe - both in that horrible turd brown for some reason.

I can imagine a certain Mr Barry Whitehouse waiting Mr. Crofts arrival, a copy of the earlier book in hand . . . "and another thing, you got this wrong too . . ."

 

[Wallace]

I see two spot faced surfaces in the photo that look like they are threaded, can you not pick up on one or both of those as an additional support?