Engine stand lock/stabilization crazy?

[mike sampsel]

So I’m nearly at the point of removing those pesky 46 mm cam nuts.
I’ve no easy way to lock my stand (keep it from rotating). Reluctant to drill a hole for pin/bolt without the okay of its owner.

Thinking of running a steel plate from the bolt on the plate to a wood four x four on the floor. Seems this would help stabilize my stand (which wants to tip at times). Not sure about the ability of the setup to handle the torque needed to remove cam nuts.
Photo shows my wild and crazy approach.


Seems I might make progress by removing my rocker arm shafts before I remove the cam nuts while I await for a better locking method. Is there a reason to not remove the rocker shafts with cam nuts on?

[carlvs]

What kind of stand are you using? I’m currently in the market for one for my upcoming 996 tear down and looking for any recommendations.


Sent from my iPad using Tapatalk

[SCadaddle]

How about:

1) Find the largest bolt you have that will fit in the existing hole in the top of the stand (the new red part) that is holding the part mounted to your engine...

2) grind the shiny red paint off of the stand at the hole...

3) Find a nut that will fit the bolt you found that fits the hole....

4) Weld the nut to the shiny red stand at the hole.....

5) Thread the bolt through the nut and tighten it against the part that is attached to your engine.

Now you can rotate your engine infinite positions and tighten it down in your stand.

[boyt911sc]

Mike,

My very first engine tear down in the mid 90’s was some what like yours. I used a four feet long chain and a couple of bolts/nuts to secure the engine from rotating. Use the long studs for the starter when loosening the cam bolts. Another method I tried was using a 4-ft. long pipe passed thru the engine yoke.

A socket and impact wrench will do a better job loosening the big nut instead of a crowfoot. I used a crowfoot the first time and now have the correct socket for the job. Just make sure the engine stand is stable when you applied the force to break loose of the big nut. Stay safe.

Tony

[mike sampsel]

Originally Posted by SCadaddle

How about:

1) Find the largest bolt you have that will fit in the existing hole in the top of the stand (the new red part) that is holding the part mounted to your engine...

2) grind the shiny red paint off of the stand at the hole...

3) Find a nut that will fit the bolt you found that fits the hole....

4) Weld the nut to the shiny red stand at the hole.....

5) Thread the bolt through the nut and tighten it against the part that is attached to your engine.

Now you can rotate your engine infinite positions and tighten it down in your stand.

It’s a good way if you have welding equipment. It’s what the owner of this equipment I’ve borrowed does, I’ve seen photos. A cheaper way is to buy a yoke with four hole although not a versatile. Welding equipment is 300+. Yoke for 250. Will consider

[mike sampsel]

Originally Posted by boyt911sc

Mike,

My very first engine tear down in the mid 90’s was some what like yours. I used a four feet long chain and a couple of bolts/nuts to secure the engine from rotating. Use the long studs for the starter when loosening the cam bolts. Another method I tried was using a 4-ft. long pipe passed thru the engine yoke.

A socket and impact wrench will do a better job loosening the big nut instead of a crowfoot. I used a crowfoot the first time and now have the correct socket for the job. Just make sure the engine stand is stable when you applied the force to break loose of the big nut. Stay safe.

Tony

So Tony, you have a 46 mm socket which just goes on the big nut? What about holding the center of the cam, is not needed with impact socket?
I just bought a new impact wrench (my tank might be a bit small 20 gallons).
Wrench is 1000 ftlbs breaking torque.

I hear you on a stable engine stand!

[Walt Fricke]

Mike - air tools are great. Your 46mm socket and a 1/2" impact wrench (my socket is a 3/4" socket, so I have an adapter down to 1/2")will bust that nut loose right away. Your tank will be just fine for this - it's not like it takes more than a couple of seconds. Leave the chains and tensioners on, or use a C clamp to hold the idler tight. I've done this by pinching loose chains together with a hand. This will put no perceptible torque on the whole engine.

In you situation I'd consider leaving the rockers in for the moment, so the valve springs will help resist the cam turning. But you don't have to.

Now, when you come to putting the engine back together and want to tighten the nut, that's different. However, you will use the cam holder tool to hold the cam. Be sure to have a pipe to put over the handle of the holder unless you are a gorilla. I prop my pipe on the floor so I have two hands to hold the torque wrench with the crow's foot extension. But you want the engine to be pretty much locked to the stand.

[mike sampsel]

Originally Posted by Walt Fricke

Mike - air tools are great. Your 46mm socket and a 1/2" impact wrench (my socket is a 3/4" socket, so I have an adapter down to 1/2")will bust that nut loose right away. Your tank will be just fine for this - it's not like it takes more than a couple of seconds. Leave the chains and tensioners on, or use a C clamp to hold the idler tight. I've done this by pinching loose chains together with a hand. This will put no perceptible torque on the whole engine.

In you situation I'd consider leaving the rockers in for the moment, so the valve springs will help resist the cam turning. But you don't have to.

Now, when you come to putting the engine back together and want to tighten the nut, that's different. However, you will use the cam holder tool to hold the cam. Be sure to have a pipe to put over the handle of the holder unless you are a gorilla. I prop my pipe on the floor so I have two hands to hold the torque wrench with the crow's foot extension. But you want the engine to be pretty much locked to the stand.

Oops I took the rockers off today.

Thanks for the tip Walt, I’m going to order a 46 mm socket today. Your advice about install will be heeded. By then I can determine the best way to lock my stand. This air impact method will save me some time. Thanks again.

[boyt911sc]

Mike,

Put the flywheel back on the crankshaft so you could keep the crankshaft from turning. Then find a piece of flatbar 1” wide and about 6” long with 2 holes or a suitable box wrench. I use a mechanical lock on the flywheel to keep it from turning. I weigh less than 140 lbs. and have a bad back. I could not lift a car battery without feeling the strain on my back. Yet, I tear down 911 motors with minimal effort. The trick is using the correct tools and techniques.

Do you have a mechanical tensioner installed now for the removal of the cam nut/s? Some people use vise grip. And because I am not big and strong, I use leverage by using long extension for the breaker bar.

Since you are using crow foot, make sure the engine stand is stable and the engine not turning over when you are removing the cam nut. That’s the reason an impact wrench makes a big difference. Stay safe and take your time.

Tony

[piscator]

Originally Posted by boyt911sc

Mike,

Put the flywheel back on the crankshaft so you could keep the crankshaft from turning. Then find a piece of flatbar 1” wide and about 6” long with 2 holes or a suitable box wrench. I use a mechanical lock on the flywheel to keep it from turning. I weigh less than 140 lbs. and have a bad back. I could not lift a car battery without feeling the strain on my back. Yet, I tear down 911 motors with minimal effort. The trick is using the correct tools and techniques.

Do you have a mechanical tensioner installed now for the removal of the cam nut/s? Some people use vise grip. And because I am not big and strong, I use leverage by using long extension for the breaker bar.

Since you are using crow foot, make sure the engine stand is stable and the engine not turning over when you are removing the cam nut. That’s the reason an impact wrench makes a big difference. Stay safe and take your time.

Tony

Good advice Tony! +1

[Nditiz1]

Not bad advice, but as far as the owner I don't think they will be upset the HF/JEGS $60 engine stand will have a new hole in the yoke. If anything they will wonder why they didn't do it sooner.

[911pcars]

The factory cam nut tool has two components, a nut removal wrench/socket and a tool to counter hold the nose of the camshaft. Sounds like you only have half the set which is why you’re using the engine. If replacing the chains, probably ok, but good chains shouldn’t be subject to that loosening/tightening torque.

Sherwood

[mike sampsel]

Originally Posted by 911pcars

The factory cam nut tool has two components, a nut removal wrench/socket and a tool to counter hold the nose of the camshaft. Sounds like you only have half the set which is why you’re using the engine. If replacing the chains, probably ok, but good chains shouldn’t be subject to that loosening/tightening torque.

Sherwood

Sounds like you’re not a fan of using an impact gun to loosen the big nut. Interesting the impact gun easily spins the nut of the rear crank wheel without locking the crank.
Trying a breaker bar 24” ion the same 17 mm nut was futile (rotated the whole engine). Not clear the impact gun will put unreconcilable torque on the chains.
Waffling

[Walt Fricke]

Sherwood - I'm not a motorcycle guy, so I don't have the special expertise with chains those guys do. My understanding, from reading and asking around, is that what causes chain "stretch" is wear on the internal pivots - the pins and the cylinders they reside it. It seems that the chains themselves are harder than the chain gear teeth, which are a kind of wear item, so it isn't the external part of those tube cross links which wear? But surely the chains themselves are plenty strong to hold the kind of forces involved here? If excessive stresses are involved, I'd think it might be on the other parts of the cam drive, like the aluminum IS gear? Or the idler arm?

The cam chains have a slack side and a tension side (the IS gear pulls the chain to turn the cam, and that's the tension side, and is the side with the plastic guides). Tightening the big nut on one side could be resisted by the tension side. But on the other side it is the slack side. The idler and tensioner deal with the slack, but in a running engine don't have a lot of stress on them. Using the slack side to hold the cam in place is going to place a lot more stress than normal on the idler system.

I once found an idler arm was cracked, which altered its geometry and put it too close to the chain box case - which is how I noticed it. I couldn't understand how this forged steel piece (or is it cast?) could develop a crack. It gets a lot of repetitive stress, but not all that heavy a load.

In thinking about this I now wonder if perhaps I had used the chain to hold the big nut, maybe when removing it from one side before I got the 46mm socket? I had both cam tools by the time I first disassembled a 911 engine, but not the socket.

I see that Wayne Dempsey suggests that the chain could be stretched or broken. Maybe he had that happen? He is an engineer, and maybe he calculated the forces involved?

He also shows making a flywheel lock in the way Tony described, and his book has a picture. Lots of us just use a suitable combination wrench if the flywheel is still attached.

Of course, you can use the cam holder to counterhold the cam when removing the nut with the crow's foot, just as you can when tightening it. And when loosening or tightening, there is no unnecessary stress on things if you lock the flywheel, but either use the impact wrench or holder for loosening, and the right tools for tightening.

Me, I remove the flywheel if I am going to split the case before I put the holder on the engine and put it on the stand. Easier access with the impact gun for spinning the bolts out with the engine sitting on the floor, and much more stable a situation when torqueing the bolts going the other way.

But there are various ways of doing this. Everybody who does this stuff more than once develops his own procedures for some aspects of the work. For instance, I think not everybody likes to use the impact wrench. Tony and I do, so you can be assured it isn't going to destroy your engine. Porsche doesn't mention this in the shop manual. Wayne Dempsey (our host here on Pelican, whose book on 911 engines I assume you have) doesn't mention using an impact wrench for loosening.

I join those who suggest you contact the owner of the yoke and stand, and see if he is OK with putting two vertical holes in the stand (drill right through it, so you can stick a big punch or other steel rod through from the top), and two pairs of holes in the holder, so you can hold the engine horizontal (or upside down), and vertical with two aspects. More practical than tightening and loosening a screw in a welded bolt. That works, but is not as positive in holding the things as a through pin, and depends on the end of the bolt poking into the yoke's tube. For the 4 arm engine stands/yokes, screwing a bolt in may be best if the mounting bolts for some engines won't leave the block at the angle you want if you just have holes and a pin. The Porsche holder (which receives the yoke) has a hole, and the yoke has holes for the two orientations. But it also has a clamp feature for finer adjustment, to squeeze the base tighter. I've never used that, but it might be useful for some procedures.

[911pcars]

Walt. Do certain impact guns provide an accurate torque setting when tightening? If so, I can see no danger in overtightening that large cam nut and/or placing undue stress on chain and sprocket (and perhaps master link assemblies). Otherwise........YMMV.

Perhaps less experienced hands may not understand the nuances with the various threaded fasteners in the engine and the number of aluminum threads accepting steel fasteners especially if corrosion has overtaken the torque to yield threshold. A race engine is more likely to have relatively fresh thread joinery unlike an engine with internal parts yet to see daylight after 40 years sitting idle in a proverbial barn (or equivalent).

As for the engine yoke, if one is to use just one pair of holes in the yoke to lock the engine in place, other than being able to roll it around, that limits convenient access to all sides of an engine. I would prefer 4 pairs of holes drilled in the yoke for a lock pin. That way, I can rotate and lock the engine position at 45º intervals.

And I should suggest using only engine stands that have 4 wheels; nothing less for stability. The sound of a fully equipped flat six hitting earth can't be a very pleasant aural experience.

Due to limited working space and funds, I built my first engine on a sturdy work bench and a lazy susan. I was able to flip the short and long block on end and on its side to access everything except the heat exchangers which were installed on the car. Friends, relatives and other muscle took care of the major lifting.

Sherwood

[Walt Fricke]

Sherwood - I don't use the impact wrench for torqueing anything. I've gotten pretty good with my impact wrench and compressor for lug nuts - I'm swapping wheels all the time at the track, oldest for practice, newer for qualifying or a race. I seldom get much movement before the torque wrench clicks. But the gun gets things close and I do the torqueing with all four feet back on the ground. And sometimes I do get a half or quarter turn, making me glad I didn't skimp like I am inclined to want to do.

When bolting the 6 bolt flywheel to the crank I use the impact to start with - spin all six in tight but not to full torque, pull one and apply red Loctite, spin it back in, repeat, and when all are back in use the torque wrench. Keeps the liquid from getting onto the mating surfaces. But for a street motor you can use regular torque and don't need Loctite.

So the impact wrench is used only to REMOVE the big cam nuts.

When setting the cam timing I get it to where I want it, partly tighten with the crow foot, maybe 1/2 to 3/4ths final torque, rotate the engine to see how close I still am, repeat as needed, and when I think I am good I do the final torqueing. After the partial torque things don't seem to move. The partial torque is not only easier to do, but easier to back off if I have to try again. I don't trust the impact wrench to get to a specified torque.

It is kind of amazing, how much the impact part does its thing in loosening and reduces overall turning effect. Come to think of it, torqueing lug nuts to 90+/- lbs/ft, you'd think the impact wrench might try to twist your hand and arm off. Doesn't, though. Wrench doesn't have all that much mass, either.

If you use a regular drill motor, line or battery powered, to spin a regular nut on a stud, when the nut seats you really feel the torque in your hand/arm because the parts you are fastening don't move. I can tell if I have mine set on lock vs. one of the drywall settings.

Anyway, no dangerous stresses buzzing the big cam nut off, and lots simpler/easier.

I asked a good track tire guy about torque sticks. He uses them, but checks with a traditional wrench.

[Walt Fricke]

I suppose being able to set the engine at a 45 might make some operation easier. Since I could do that on my Factory yoke holder with the clamp part, but don't recall being tempted to do so, I kind of discount that.

I wonder if having 8 holes in a tube would weaken it enough to matter when torsion forces are applied? Probably not, at least with a decent wall thickness? If you'd had a problem you wouldn't recommend it.

My experience with holes through tubes which slide in and out of each other made me think how hard it was for me to make a seat back brace bracket which was adjustable by a through pin. It was easy to drill the first hole through both tubes when they were nested so everything lined up. But getting the second set in the inner tube to line up true to the lower hole on the outer tube(which was welded into the car's roll cage) was tricky. The yoke looks tricky enough to hold true in a drill press, and the stand well neigh impossible. But doubtless there is a way to do it. By fudging a bit side to side I got my brace to work, and someone with better fabricating skills probably would have no trouble at all.

[911pcars]

Beginning with the existing pair of holes in the yoke, I recall using math to determine the circumference, then divided by 1/4 to mark two holes 90º from the existing holes, then so on for 45º holes.

One trick is draw a straight line on a piece of paper parallel to the edges, layout, measure and mark the appropriate circumference marks as explained above, then wrap it around the yoke and tape in place so the lines intersect (the wider the paper, the more accurate the line will ID the exact opposite pipe wall), then transfer the hole centers through the paper onto the yoke. Fabricators use this method to layout cuts in tubing for exhaust systems and roll cages, etc. Drill pilot holes, then graduate to a drill size or two larger than the supplied pin.

BTW, if there's a materials strength concern, there's no rule that says additional yoke holes have to be as large as the primary hole. A large Phillips screwdriver with smallish yoke thru-holes could hold the engine in the preferred position.

It doesn't have to be nuclear power plant accurate as long as the holes on both tubes allow the pin (or screwdriver) to pass through. Repeat as necessary.

Sherwood

[mike sampsel]

Lots of good ideas and information provided. My tube is borrowed from a friend. It’s heavy duty thickness 2x or more than the harbor freight stand one. Drilling on it will take years LOL! I’m just trying to get ahead of schedule to send my heads off for valve stemming etc. I’ll buy a four hole yoke for torquing of the cam nuts.

So since I’m replacing my chain sprockets with post ‘81 style, and will replace my mechanical tensioners (hoeptners they are) with Carrera oil fed, no worries here. And since as Walt said, the impact gun doesn’t even twist in your hand, thinking removal of cam nut with an impact gun is safe. It’s like when I spun off the nut on the rear crank pulley, engine stand not locked, but the nut spun off in 30 sec! When I used my breaker bar to attempt, (crank locked with one bolt in crank) the whole engine rotated in the stand. Here you get a lever arm affect, not so with impact gun.

But, I’m going to determine ETA of a four hole yoke today. Just to have the data. Then go into analysis paralysis

[boyt911sc]

Originally Posted by mike sampsel

Lots of good ideas and information provided. My tube is borrowed from a friend. It’s heavy duty thickness 2x or more than the harbor freight stand one. Drilling on it will take years LOL! I’m just trying to get ahead of schedule to send my heads off for valve stemming etc. I’ll buy a four hole yoke for torquing of the cam nuts.

So since I’m replacing my chain sprockets with post ‘81 style, and will replace my mechanical tensioners (hoeptners they are) with Carrera oil fed, no worries here. And since as Walt said, the impact gun doesn’t even twist in your hand, thinking removal of cam nut with an impact gun is safe. It’s like when I spun off the nut on the rear crank pulley, engine stand not locked, but the nut spun off in 30 sec! When I used my breaker bar to attempt, (crank locked with one bolt in crank) the whole engine rotated in the stand. Here you get a lever arm affect, not so with impact gun.

But, I’m going to determine ETA of a four hole yoke today. Just to have the data. Then go into analysis paralysis

Mike,

We could argue all day which method is better than the other one. But at end of the day, you have the final say. Since this is your first engine tear down, I understand the anxiety and concern you are having. But if you have done a few engine rebuilds and physically not built as NFL line backer, you will seek different ways to do things to overcome some of these problems to your advantage.

I am using my self as an example and I would bet you are much bigger and robust than me. Weighs 138 lbs soak and wet, suffering from herniated disc, had torn meniscus on left knee (operation done), have back strain carrying my golf bag from parking lot to the driving range (did it last night), suffering with sciatic nerves, 76 years old, used to be 5’8” tall (now stands less than 1/4”), etc. if you were closer to me, I would offer to do the work myself. This is how simple this task we have been over analyzing.

If I were in your shoes since you have the crowfoot and cam holder, is to try it first. You are over thinking this one and hundreds of people have done this before with no problem. To make you feel better, get an assistant/helper when you loosen the cam nut. I had my wife in the garage when I first did it. She was holding the step stool supporting the cam holding tool. Piece of cake.





So if a weakling could break loose these cam nuts alone, I don’t see why you could not do it with a helper. Stay focus on the job. Be safety conscious. You will succeed.

Tony