Power drain from Timing Chain / Valuable Build Tips herein...

[PMC raceengines]

Yer its the brake away that takes 14foot/ pounds , after its moving its lots less , but the crank by its self should spin free with a finger . With the rear main seal in

Edited April 7, 2012 by PMC raceengines

[rsicard]

Any techniques you can share to get the crankshaft and bearings for same to fit such that it will spin free once installed? Please advise. Thanks.

[Xnke]

After working my own rebuild, with the crank only in the first block I tried It would not spin more than 1 full turn after I let go...with the second block, I got three full rotations out of a good spin on the damper...mind that this was the crank, in bearings, with the rear main seal on it. I chalked it up to a slightly warped block.

[PMC raceengines]

Well i read how to modify your nissan and datsun ohc engine more than once lol

 

straight from that book

With a 2-3in. micrometer, measure the main bearing journal . adjust the dial bore gage with the micrometer set to journal diameter . Measure bearing ID in three places-vertical, and at 45 to vertical on each side . exchange the bearing shells as needed to achive 0.0022 -0.0027in clearince.

 

This is how you do it its slow and not fun but it the only way . you can not do the job with plastigage .

 

ONE thing you must check is that the tunnel is right and the caps have not been hit with a hamer to fit , more than once i have seen the rear cap out of round . once the block is right make shore the crank is straight and round , and thats not that offten the case ...

Also i have a dimond laping plate and i work the thrust bearings to get exact end play , there are little things that can make a difrence like sharp edges and lips on caps that can lift bearings'.

Its a job that you get better as you go, lots of years to get the feel you need to build a race wining engine

Edited April 8, 2012 by PMC raceengines

[rsicard]

PMC raceengines:

 

Thanks much for the tips. It seems that the best way to do the fitting of the crankshaft and main bearings is to use a coordinate measuring machine (CMM) to map the exact tolerances of the main bearings and the crankshaft journals. Making certain that the crankshaft main journals are all exactly where they should be. Secondly, with the main bearings inserted and torqued down, use the CMM to see how exact ALL of the main bearings are where they are supposed to be. Even after the main bearing journals have been Line Honed, inserting and torquing the bearing shells, these shells could well be out of exact alignment. Swapping the bearing shells around may solve SOME of the out of alignment, but not all of it. Maybe if there were THREE sets of NEW bearing shells, then the best of the lot can be selected for use ONLY after careful torquing and measurement to get as EXACT alignment as possible.

[Tony D]

Thanks PMC, this is all "straight from the book", the Datsun bearing shells were available in various backshell thicknesses of EXACTLY the reasons mentioned.

 

It's good to see some others interested in the "art" of engine building, rather than mere "assembly"! Many pooh poohed the "Industrial Arts" wing of high school thinking it was for the losers who couldn't hack it in the AP Classes and "needed" to work with their hands. Lots of disrespect for the ART that is endemic to mechanical work.

 

FAR too many people see it simply as something that can be codified, annotated, abbreviated, and replicated "by any trained monkey"--these are the same ones who don't like long answers because they are "un-necessary and overly complex, this is a simple procedure!"

 

There is Art in all aspects of life. If you cultivate the art, indeed it's simple to get good results. If you view it as mere assembly work, you will remain amazed when you see it done properly.

[Xnke]

Yeah, I didn't have the money when I built mine for multiple sets of bearings, but I did have a few blocks laying around and so picked the one that fit my crank and my bearings the best. Rods were a different story...got the bearings fitted in the rods, measured, fitted, measured, fitted...re-fitted the rods to the crank one at a time and finally got the rods to hang vertically while the crank turned. Was able to use two fingers on the small end of the rod to turn the crank, and all the rods on it, pretty easy...called that good enough and went on to fitting the pistons and rings.

 

It is pretty amazing what being picky about things can get you.

[rsicard]

What PMC has said is all fine well and good. What I was getting at is the actual TESTING for position tolerance of the Main Bearings and inserts for same, in relation to each other, assembled and torqued less the Crankshaft. This same level of testing of the crankshaft to make CERTAIN that the circumference of each main bearing is in line, or concentric, with each other Main bearing. Then this SHOULD allow the least amount of friction once the Crankshaft is assembled into the Main Bearing Saddles along with the bearing inserts. Not certain whether this is "ART" seem more like "SCIENCE".

 

Constructive comments invited.

[roger280zx]

What PMC has said is all fine well and good. What I was getting at is the actual TESTING for position tolerance of the Main Bearings and inserts for same, in relation to each other, assembled and torqued less the Crankshaft. This same level of testing of the crankshaft to make CERTAIN that the circumference of each main bearing is in line, or concentric, with each other Main bearing. Then this SHOULD allow the least amount of friction once the Crankshaft is assembled into the Main Bearing Saddles along with the bearing inserts. Not certain whether this is "ART" seem more like "SCIENCE".

 

Constructive comments invited.

And this, to TonyD's point, is exactly why you're not getting it. It certainly is art, and you're not giving it that credit, and benefit.

[rsicard]

An answer with emotion and not fact is not an intellectual answer. Art and Science are two different things. Art is tied more to emotion. Science is not. The best science is based on known and provable facts.

[roger280zx]

So sorry to offend with my so obviously emotional answer. Maybe the word "Craft" is less offensive, and we can deem those who employ the Art as "Craftsmen" the way that Websters Dictionary does. Could we move on with the tensioner discussion now, or is 7.5 hp at 8000rpm the final answer. My assumption would be that through the stabilization of the timing chain the engine may see less wear over time. In other words hold on to more horse power that would other wise be lost to slack in the chain over a period of time. Is there any evidence to that theory?

[PMC raceengines]

Right back to the timing chane .. One thing i have noted is the hp is not lifted as much if the twin idler is not needed

, if the head and block have been shave more than they should, the slack side guide will cost you lots of power as the chane needs to go over a nasty angle at the top and the chane goes slack after the guide. so the twin idler works very well in this situation ,

 

But if you have not removed to much from the head and the factry style guide is well with in spec

there is very little in it

 

For high rpm like 7000+ the twin idler helps with timing [cam timing ] stay stable and this with less drive loss over the guide has to help make hp

[galderdi]

Wow, thanks for all the replies. It has certainly informed my decisions. I am building a race / road engine. It is balanced so I would be expecting to occasionally hit 7000RPM on the track. I am targeting around 175 HP at the wheels. The head has been milled but not extensively. It still sounds like the twin idler is a nice to have rather than a necessity. The replies have come at a good time as I have just finished assembly of my bottom end so I will immediatly check the number of rotations. I have had my bottom end checked and it is true, but I'm not sure how my bearings will fit.

[PMC raceengines]

Sorry if my reply was short on detail ,, Its a job that takes detail lots of it, some times thats not to easy to put into words after 25 years of fitting bearings you get in to habbet. And its good to read lots of manuals to inprove your skills ,

Things like fitting the main bearing with out scraching the back as you fit them , scraching the back as you work them in to the block can lift the bearing and reck your hard work .

Next time you fit a set check to see if there is a small amount of backing metal at the edge of the bearing shell ,, if there is you did not fit it right .

 

And most 77style bearings have a lip at the edge that will measure 0.0002 high ,so you need to make shore thats what it is, not some other thing that will make the shell wear

 

When you get to the point where your fitting the crank and its not spining free remove the caps one at a time and look for a smooth spot on a shell . If there is no spot that you see remove the thrust and fit the crank and check to see if it spins free if it does remove the crank and look for a reasion on the thrust ,,, Often the cap has a small dag or sharp edge that can lift the bearing ...

 

The best tool in the shed is your eyes make shore you use them, detail is key and make shore you are clean, and your engine room is cleaner than your kitchen and your hands must be clean all the time

 

When you think you know how and stop reading and going over basic stuff, your in for a sharp slap of reality basic stuff is all inportant to get the edge

 

thanks peter mc

Edited April 8, 2012 by PMC raceengines

[Tony D]

PMC has ONCE AGAIN proven and pointed out the disconnect riscard has, and why he won't get it no matter how hard anybody tries.

 

No matter how much you codify, or try to codify this process unless you do it for EVERY SINGLE COMPONENT USED IN THE PROCESS it will not work.

 

ONE variable off, and it doesn't work. Then where's your logic flowchart to find where the problem lies.

 

Riscard foolishly believes if you control SOME aspects of the process you will arrive at the result desired. You will not. You must ALWAYS check and recheck components. You can, as PMC pointed out have straight bores, but defective compoentry that measures correctly... But had an imperfection that does not evidence itself until assembly.

 

When the engine is put together on the Nissan Assembly Line, ALL ASPECTS of the assembly are controlled. THERE is the ONLY PLACE you can engineer in consistency.

 

After that, in the field.... It's art. Unfortunately there are far too many engineers like riscard sitting in offices thinking field conditions mirror an assembly line environment. They do not. The only thing I can say is, if it were not art, and only science every single engine builder out there would take components and assemble engines ONCE. there would be no trial fitting because everything is measured and confirmed beforehand.

 

Yet not a SINGLE engine builder of performance engines on ANY level of competition (including F1, where arguably it's all science!) doesn't do a trial assembly to check for glitches that can not be determined by measurement.

 

No disrespect here, but it simply looks to me that riscard simply hasnt assembled that many engines to have these truths revealed in good order.

 

As PMC (paraphrased) said: "your best tool is your own eyes"

 

Remember this started as a contention that crank friction was more than rings, and that valvetrain was not the frictional drain in the L-Engine.

 

I think that has been answered, we should stop muddying the thread, and have this proper assembly of engines moved to a different thread.

 

I think it's been shown now from several aspects that if there is friction in the bottom end, something was dine wrong in assembly.

 

Talking with a former Ford Corporate wonk, his comment was that a V-8 crank, with both seals and even 1 or 2 psi of oil film supplied to it should "Spin freely to a stop dependent on the lip seal friction present-the crank should be on oil film and present no appreciable friction loadings when lubricated." for dry spinning he said "pinky on 3/8" ratchet" and with pistons and rings "no more that two fingers on the same ratchet"... So it's the same for domestic V8's as well. I thought as much.

[rsicard]

TonyD:

 

I don't see where there is a disconnect. If each of the journals of the Crankshaft and Main Bearings, with shells installed, is visually inspected and tested for concentricity and proper clearances, then when the two are assembled with proper lubrication there should be minimal level of friction. This can be quantified with an inch pound torque wrench.

 

As for engine experience, I have owned three aircraft and rebuilt engines in two of them guided by a qualified A&P mechanic. Also renewed a Peugeot, Renault, Volvo (PRV) aluminum V6 under the guidance of an experienced mechanic. Rebuilt a BBC 454 now 489 cu in and in my truck and it runs VERY WELL. Rebuilt a 350 SBC for my 240Z bored and stroked to a 383. Used a tested baseline of 500 HP/TQ and exceeded every specification for same. Fabricated a test stand and both the 489 and 383 run in and tested on the stand. Both run just fine. The 383 has the most accurate and flexible EFI system installed ever made.

 

As far as friction is concerned, see the article at: www.fev.com/ content/ public/ secure/ protecteddocs/ OptimizedCranktrainDesignSupportedbyCAE.pdf.

[galderdi]

I installed my pistons yesterday. I noticed that all the characters cast onto the end caps for the con rods were all the same direction except 1. I removed the offending end cap and was surprised to find the bearing notch was on the other side compared to the other caps. So I have replaced it with the orientation of the bearing the same as the others. This means the characters on the cap are still the wrong way around but the bearing is correct. Should I be worried?

 

I haven't tensioned any of the con rods yet so I can still correct it if the cap orientation is more important than the bearing orientation?

[Tony D]

"So you've assembled 5 engines..."

Indeed, riscard, then why on earth if you have done this is the concept of an engine turning over with a twist of the hand such a foreign concept to you? And why express such disbelief of it's possibility?

 

This needs to be in another thread. And you should probably read less and do more.

 

To the OP's most recent question: were the pistons removed from the rods? Are the notches in the pistons all facing the way they should be... The rods all should be the same way. Same for directional notches on the pistons. It is possible if you had the pistons pressed on by a shop they did one backwards--which they now must remedy. The caps ... Were they resized?

Edited December 27, 2014 by Tony D

[galderdi]

Yes they are new pistons pressed on to the original rods by the machine shop. The piston notch is pointing the same way as all the rest. I did think of the possibility of the con rod being pressed in the wrong direction but the notch for the bearing is in the correct direction (same as the other 5) it is only the characters on the cap that point the other way. The caps have not been resized.

[Tony D]

Ohhh, something doesn't sound right. Nissan Caps and rods are all numbered 1-6 and they all are on the same side. If the cap was resized for out of round then if they put it on wrong way round to resize it you live with it. But this seems very odd. This may be a time when a couple of photos are worth thousands of words.