The dry sump Gordini motor.

[Andrew Watkins]

It made me feel better when I got the "go-ahead" from #Greenpeace and #dauphproto. It means that my idea isn't just grabbing at twigs as I'm falling out of a tree.

But now I'm in a little bit of a dilemma. The stretch bolts are on their way, and, I found the misplaced bolts. I even have 4 spares. What to do now? Go ahead with the new idea or fall back to the original bolts.

Weird how a big yellow klipon bin marked "Gordini Specific Spares" can disappear like that and then suddenly pop out of hiding and place itself in plain view on the garage floor.

Regards, Frans

It‘s called X-linked blindness

Jan points this out frequently

ANdrew

 

[COL]

It made me feel better when I got the "go-ahead" from #Greenpeace and #dauphproto. It means that my idea isn't just grabbing at twigs as I'm falling out of a tree.

But now I'm in a little bit of a dilemma. The stretch bolts are on their way, and, I found the misplaced bolts. I even have 4 spares. What to do now? Go ahead with the new idea or fall back to the original bolts.

Weird how a big yellow klipon bin marked "Gordini Specific Spares" can disappear like that and then suddenly pop out of hiding and place itself in plain view on the garage floor.

Regards, Frans

I would go with the original bolts as they were designed and are proven to work, the stretch bolts are an experiment, although would most likely work satisfactory.

Inattentional Blindness, I think we all suffer from this from time to time.

Inattentional Blindness Can Cause You to Miss Things in Front of You

Inattentional blindness is the psychological phenomenon that causes you to miss things that are right in front of your eyes. Learn more about why it happens.

www.verywellmind.com

I think it is known as having a daddy look instead of a mummy look.

 

[Greenpeace]

I'd agree with Col. So long as the original bolts stand up to scrutiny, they are the ones I would go for.
It would be an interesting experiment to mark the bolts with a dab of white paint once you've applied the initial 30Nm and see where they end up degrees wise once you've fully torqued it down.
I've had some engines where I swear some bolts take 1/2 a turn more than others to reach the manufacturer's maximum torque setting.

 

[JohnW]

It made me feel better when I got the "go-ahead" from #Greenpeace and #dauphproto. It means that my idea isn't just grabbing at twigs as I'm falling out of a tree.

But now I'm in a little bit of a dilemma. The stretch bolts are on their way, and, I found the misplaced bolts. I even have 4 spares. What to do now? Go ahead with the new idea or fall back to the original bolts.

Weird how a big yellow klipon bin marked "Gordini Specific Spares" can disappear like that and then suddenly pop out of hiding and place itself in plain view on the garage floor.

Regards, Frans

I was going to ask you which length bolts you needed, so I could post them over, then I read the stretch bolts discussion. I like it.

 

[JohnW]

I'd agree with Col. So long as the original bolts stand up to scrutiny, they are the ones I would go for.
It would be an interesting experiment to mark the bolts with a dab of white paint once you've applied the initial 30Nm and see where they end up degrees wise once you've fully torqued it down.
I've had some engines where I swear some bolts take 1/2 a turn more than others to reach the manufacturer's maximum torque setting.

I'm thinking this torque business isn't as accurate as we might think! Are the old style bolts consistent from bolt to bolt? Is the lubrication consistent from thread to thread? How is the surface finish of the various threads? Torque is just the surrogate for clamping force after all. I guess there are engineering PhDs on this stuff.

As ever thanks for this fascinating thread!

 

[Greenpeace]

I'm thinking this torque business isn't as accurate as we might think! Are the old style bolts consistent from bolt to bolt? Is the lubrication consistent from thread to thread? How is the surface finish of the various threads? Torque is just the surrogate for clamping force after all. I guess there are engineering PhDs on this stuff.

As ever thanks for this fascinating thread!

Yes, one would think if you ran a die over the bolt threads a tap down the block threads, ensured there was virtually no rotational resistance in the holes in the head, and were very careful with applying the lubricant evenly: (providing all the bolt were the same length), one would expect there would be little difference in the degrees of rotation required to meet the max torque setting (after the initial "seating" torque has been applied).
Problem is a lot of engines have different length bolts, and many, (old Holden 6s and V8s for example), you have to put thick thread sealer on the bolts, as many of them go into water jackets.
That would have to "soak up" more of the torque applied than a well oiled bolt would.

 

[Greenpeace]

Just in case anyone has the urge to rebuild an early Holden V8 (pre VN).
Each head has 12 bolts the same size, 10 around the cylinders in the normal fashion, and two extra ones in between the paired inlet ports.
The 10 regularly located ones are 75 ft/lbs, BUT, in spite of being the same size bolt, the inner 2 are only 55 ft/lbs.
A lot of online blogs and even non-factory literature, fails to mention this.
A mate of mine found out the hard way when he applied 75 ft/lbs to all the head bolts and one of the inner ones broke a big lump of cast iron free from the block in the engine's valley, instant boat anchor.
The later Holden V8s (VN on) with the evenly spaced ports, don't have these extra 2 bolts.

 

[dauphproto]

It made me feel better when I got the "go-ahead" from #Greenpeace and #dauphproto. It means that my idea isn't just grabbing at twigs as I'm falling out of a tree.

But now I'm in a little bit of a dilemma. The stretch bolts are on their way, and, I found the misplaced bolts. I even have 4 spares. What to do now? Go ahead with the new idea or fall back to the original bolts.

Weird how a big yellow klipon bin marked "Gordini Specific Spares" can disappear like that and then suddenly pop out of hiding and place itself in plain view on the garage floor.

Regards, Frans

So it's not Just ME then..............

 

[dauphproto]

Incidentally, on the subject of minimising friction on bolt threads and washers, you can really tune up your Bench vice, but care must be taken.
I got hold of a Flat thrust race which is 2 Hard, ground washers with a set of needle rollers between them. I fitted this to my Record Bench vice between the moving Jaw and the threaded Acme handle. This removes all of the Friction between the 2 bits of the Vice as it is tightened, it was good and bad. It Quadrupled the clamping force of the vice, but it was then easy to distort things that you put in it. Finally I killed it with a Differential (a Big Salisbury) being held while the Pinion nut was tightened. It is one of those things, it kept slipping in the vice, so I slipped a bit of pipe over the handle to give it the big Heave-Ho. There was a bang like a Shotgun as the moving vice Jaw Snapped in 2 and about 30 kg of Diff Started towards the floor.
Play Safe...........

 

[Greenpeace]

Interesting story on reducing friction.
I'm sure many of you would have heard of NASCAR driver/engineer/team boss Smokey Yunick? He was legendary for finding loopholes in the rules. The 5 gallon fuel line mentioned in the movie Days of Thunder, true story, that was Smokey Yunick.
Anyhoo I digress, in one of his books he talks of picking up a Honda motorcycle cylinder head (that had the rockers removed) and was amazed how easy the needle roller equipped camshaft was to twirl with his fingers.
In that light bulb moment he stripped down a newly built (and dynoed) small block Chev V8 race engine, and machined everything to take needle rollers: crank mains/big ends, camshaft, rocker arms, distributor, everything.
Put it back on the dyno, and with no other changes it made................exactly the same power as it did before.
He was baffled at first, but eventually worked out that regardless of the bearing design, the bearings are "floating" on a bed of high pressure oil when the engine is running, the components were only easier to turn when it wasn't running.
Those expensive needle roller rocker arms that people lust after, will only make more power if:
1. The standard ones flex or deflect under the strain of higher lift cam/s and stronger valve springs.
2. The standard ones have significant wear.
3. The new roller rockers have a higher lift ratio built into them.
I've built engines with needle roller rockers many times, but only because the ones I used offered a higher lift ratio than the standard ones, not because they had needle bearings.

 

[Frans]

And also not just me either! If it was a snake, it would have bitten me.

In a way, I am actually disappointed I found the other bolts. I looked forward to be using the stretch bolts and I think I am going to use them. Now you can tell me that "I told you so" if it doesn't work. If I didn't find them it would have been a legit experiment that it does or doesn't work and you could have sympathized with me if I had a failure.

It might cost me but if I don't do it, we'll never know. This might just be the start of another method that can be adapted in the future and no more re-torques are required. Remember that the valve clearances will still have to be adjusted to compensate for the sagging head gasket, unlike OHCs.

Thanks for all the info on friction. I usually lubricate all the bolts's thread and washers with assembly paste. It is supposed to be a high-pressure lube. I have a feeling that with the stretch bolts and the degrees of rotation, it will be more accurate. I have experienced the same as Greenpeace in thread #163 above that some bolts take more rotation than others before the wrench "clicks". So JohnW is very correct in saying that the torque procedure is not as accurate as one would think, however, it was close enough for millions of cars pre- stretch bolts.

Regards, Frans.

 

[JohnW]

And also not just me either! If it was a snake, it would have bitten me.

In a way, I am actually disappointed I found the other bolts. I looked forward to be using the stretch bolts and I think I am going to use them. Now you can tell me that "I told you so" if it doesn't work. If I didn't find them it would have been a legit experiment that it does or doesn't work and you could have sympathized with me if I had a failure.

It might cost me but if I don't do it, we'll never know. This might just be the start of another method that can be adapted in the future and no more re-torques are required. Remember that the valve clearances will still have to be adjusted to compensate for the sagging head gasket, unlike OHCs.

Thanks for all the info on friction. I usually lubricate all the bolts's thread and washers with assembly paste. It is supposed to be a high-pressure lube. I have a feeling that with the stretch bolts and the degrees of rotation, it will be more accurate. I have experienced the same as Greenpeace in thread #163 above that some bolts take more rotation than others before the wrench "clicks". So JohnW is very correct in saying that the torque procedure is not as accurate as one would think, however, it was close enough for millions of cars pre- stretch bolts.

Regards, Frans.

Yes, I agree. Of course, most of those millions were conservative regarding performance and didn't need clamping force to be totally accurate and, of course, they were torqued up when everything was new.

I'm glad you are going to try the stretch bolts. Best wishes.

 

[Greenpeace]

And also not just me either! If it was a snake, it would have bitten me.

In a way, I am actually disappointed I found the other bolts. I looked forward to be using the stretch bolts and I think I am going to use them. Now you can tell me that "I told you so" if it doesn't work. If I didn't find them it would have been a legit experiment that it does or doesn't work and you could have sympathized with me if I had a failure.

It might cost me but if I don't do it, we'll never know. This might just be the start of another method that can be adapted in the future and no more re-torques are required. Remember that the valve clearances will still have to be adjusted to compensate for the sagging head gasket, unlike OHCs.

Thanks for all the info on friction. I usually lubricate all the bolts's thread and washers with assembly paste. It is supposed to be a high-pressure lube. I have a feeling that with the stretch bolts and the degrees of rotation, it will be more accurate. I have experienced the same as Greenpeace in thread #163 above that some bolts take more rotation than others before the wrench "clicks". So JohnW is very correct in saying that the torque procedure is not as accurate as one would think, however, it was close enough for millions of cars pre- stretch bolts.

Regards, Frans.

Put the the old bolts "somewhere safe", then you'll have to use the stretch bolts anyway.
I guess another variable for home mechanics is, how accurate is your torque wrench anyway?
My father was a mechanic and after he passed away we had to sort out his tools. For whatever reason he had 3 identical, near new, clicker torque wrenches still in their cases.
I was rebuilding a V8 engine not long afterwards that required 100 ft/lbs on the cylinder head bolts.
I thought I'd use one of Dad's wrenches, but at the final 100 ft/lb stage it just seemed a bit too easy to get it clicking.
Long story short, the three wrenches varied by 20 ft/lbs, 100 on one was only 85 and 80 on the other two. I ended up reverting back to my trusty deflection beam wrench that I've owned for 40 odd years. It required more rotation to register 100ft/lbs than the best of the clicker wrenches did.
I've attached an article on stretch bolts.
I guess the thing to weigh up is that they were introduced as a cost cutting measure to eliminate retorquing on modern engines (once head bolt access became a major issue), they weren't introduced because they were a better bolt.

stretch bolts

 

[dauphproto]

They are a good idea and provide a better clamping force, although the bolt is of lesser strength and gets into it's elastic deformation range, which can be no bad thing considering the application, this isn't going into a garage Queen.

 

[Greenpeace]

Just out of interest has anyone fitted cylinder head studs to one of these engines in lieu of bolts?

 

[COL]

And also not just me either! If it was a snake, it would have bitten me.

In a way, I am actually disappointed I found the other bolts. I looked forward to be using the stretch bolts and I think I am going to use them. Now you can tell me that "I told you so" if it doesn't work. If I didn't find them it would have been a legit experiment that it does or doesn't work and you could have sympathized with me if I had a failure.

It might cost me but if I don't do it, we'll never know. This might just be the start of another method that can be adapted in the future and no more re-torques are required. Remember that the valve clearances will still have to be adjusted to compensate for the sagging head gasket, unlike OHCs.

Thanks for all the info on friction. I usually lubricate all the bolts's thread and washers with assembly paste. It is supposed to be a high-pressure lube. I have a feeling that with the stretch bolts and the degrees of rotation, it will be more accurate. I have experienced the same as Greenpeace in thread #163 above that some bolts take more rotation than others before the wrench "clicks". So JohnW is very correct in saying that the torque procedure is not as accurate as one would think, however, it was close enough for millions of cars pre- stretch bolts.

Regards, Frans.

I think it is fair enough to go ahead with your experiment Frans, like you said if you don't do you will never know. What is the worse that can happen? You will blow a head gasket, it will cost you a head gasket and some time to replace it, and maybe ruin a race.

Pack those head bolts and a spare head gasket in your race kit that you take to the track.

 

[COL]

Just out of interest has anyone fitted cylinder head studs to one of these engines in lieu of bolts?

How many experiments do you want Frans to run?

I personally can't see any advantage to having studs over bolts in these engines as the bolts go all the way down to the bottom of the block where the main bearings are.

 

[Greenpeace]

How many experiments do you want Frans to run?

I personally can't see any advantage to having studs over bolts in these engines as the bolts go all the way down to the bottom of the block where the main bearings are.

Studs only stretch along their vertical axis when you tighten them, they don't twist, same torque = greater clamping pressure.
The nuts on a stud are almost always a finer thread than those in the block which permits more precise torquing.
Torquing down a cylinder head equipped with studs feels nothing like torquing down the same cylinder head equipped with bolts, the studs feel significantly more "reassuring".
Studs are the immediate go to with any head bolted engine that has been pushed to the point of regular head gasket failures, (due to raised cylinder pressures).
IE: supercharged, turbocharged, nitrous engines.
Virtually all of those big HP diesel motorsport engines that the Yanks love, Duramax, Powerstroke, Cummins etc, have head stud conversions, because they blow head gaskets without them.
Modern diesels went to stretch bolts because they are cheaper, (again the whole "no need to re-torque scenario") not better than studs.
Head gasket failures are fairly commonplace on modern, small capacity, highly stressed diesels, I wonder why?
You won't find any cylinder head bolts on a 10,000 bhp Top Fuel engine, or an F1 engine.
I'm not trying to talk Frans into, or out of anything.
The stud enquiry was just out of general interest.
They are commercially available for pretty well any commonly modified engine (that originally came with head bolts) for a reason.
Most likely a NA engine of the Renault's vintage, (even a high performance version), won't generate high enough cylinder pressures to warrant head studs, unless there is some inherent weakness in the original design.

 

[dauphproto]

Another short Bolt/ Friction tale. A Friend of mine was one of the quality control officers at the local Defence Aviation Repair Authority where they overhaul Military Helicopters. They started to get an issue with a highly stressed Rotor head bolt, which had to be torqued up to a ridiculous figure. These bolts were shearing before the requisite figure had been reached. Long story short, the bolts were coming from a new supplier having been soaked in Lanolin. The specs called for clean and dry. The old bolts came dry and got a wipe with a clean cloth and installed. Wiping the new bolts did not remove all of the Lanolin, so the bolts were achieving a much higher load from less torque applied. The solution was to wash and dry the bolts before installation, problem solved. We're all Men of the world here, so I'll close by saying Never underestimate the power of a bit of lubricant.......

 

[dauphproto]

Studs only stretch along their vertical axis when you tighten them, they don't twist, same torque = greater clamping pressure.
The nuts on a stud are almost always a finer thread than those in the block which permits more precise torquing.
Torquing down a cylinder head equipped with studs feels nothing like torquing down the same cylinder head equipped with bolts, the studs feel significantly more "reassuring".
Studs are the immediate go to with any head bolted engine that has been pushed to the point of regular head gasket failures, (due to raised cylinder pressures).
IE: supercharged, turbocharged, nitrous engines.
Virtually all of those big HP diesel motorsport engines that the Yanks love, Duramax, Powerstroke, Cummins etc, have head stud conversions, because they blow head gaskets without them.
Modern diesels went to stretch bolts because they are cheaper, (again the whole "no need to re-torque scenario") not better than studs.
Head gasket failures are fairly commonplace on modern, small capacity, highly stressed diesels, I wonder why?
You won't find any cylinder head bolts on a 10,000 bhp Top Fuel engine, or an F1 engine.
I'm not trying to talk Frans into, or out of anything.
The stud enquiry was just out of general interest.
They are commercially available for pretty well any commonly modified engine (that originally came with head bolts) for a reason.
Most likely a NA engine of the Renault's vintage, (even a high performance version), won't generate high enough cylinder pressures to warrant head studs, unless there is some inherent weakness in the original design.

This is the main argument for using an ARP stud conversion kit on an Engine. It's a better Engineering solution, not to mention higher quality materials.