Jump to content
HybridZ
galderdi

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

Recommended Posts

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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 by PMC raceengines

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

"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 by Tony D

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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. :huh:

Share this post


Link to post
Share on other sites

Thanks again for the guidance. I had another look and even had a retired mechanic friend take a look. The rod itself is most definatly on the correct way as all six have the divot in the side of the rod pointing the same way. The pistons are also all consistant.

 

All the caps still have the "shaddow" from the corresponding bearing notch from the rod. So from this I can see I am putting them back the same way they were fitted last time.

 

It is quite possible it was the result of someone resizing this one but it must have been a previous owner.

 

By the way this is a spare engine which I have never had running.

 

I will indeed take a couple of photos. I am also tempted to remove all the pistons and start from scratch to make sure there are no anomolies. I guess it is vaguely possible a rod and or cap could have been mixed up with another set or maybe the machine shop lost the cap and replaced it without telling me. There are all sorts of posibilities.

Share this post


Link to post
Share on other sites

I did some tests thru the week on some of the engines at work , A L28 race motor with out plugs takes 20 ftlb to turn, with race springs ,120 on the seat , 14ftlb for the bottom with rear seal and all pistons new rings fitted ..

BTW after running on the dyno for 1 hour i tested it again without plugs it now turns free with 16 ftlb :D .

Share this post


Link to post
Share on other sites

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.

 

Stumbled across the this gem....Sorry to bump an old thread.. Everybody go back to what you were doing...

Share this post


Link to post
Share on other sites

Stumbled across the this gem....Sorry to bump an old thread.. Everybody go back to what you were doing...

 

I just linked to it a couple of days ago - took me a while to find it again!  Now that it's been bumped, could we make this a sticky?  Some really valuable build advice in this thread, and it's really hard to find with search terms, even if you know the thread exists and are just trying to find it again.

Share this post


Link to post
Share on other sites

You just linked it again TimZ, which refreshed my annoyance at basic assembly discipline...that's all pretty much written down.

 

When you pour Babbitt, and scrape bearings for an engine you realize a lot of stuff people take for granted today aren't always the way it was done.

 

Three years ago, I exited our China operations because my management team claimed I had an issue with our operations there...that I was "needlessly bashing them without all the evidence being in."

 

This year, I was asked to go back... "To audit installation and service practices"... and I asked if this was a validation of my claims three years ago and reminded them of my statement when I withdrew: "When we make this connection interface bulletproof, and these guys STILL WRECK THE MACHINES, what will our excuse be THEN? Will we THEN look at the decision to employ engineers for field support, rather than hands-on technicians who take pride in their work and aren't looking for a mandarin fingernail and the coveted office job? Will you THEN listen to me that these guys are killing our machines? It's not an ENGINEERING problem, it's an installation and service personnel problem!"

 

We had a crew of guys slapping stuff together, in horrendous industrial arts fashion. There is an art or craft to putting just about anything together. You can control that process in a factory, but in the field the ONLY hope is your assemblers/field techs being competent at their craft and knowing how to assemble these things correctly.

 

My managers reply "uh, yeah...it took us a while to catch on with what was really going on there!"

 

Yeah, two week blow-through junkets and living halfway around the world -- it's easy to pull the wool over your eyes. Spend four months a year there and you see stuff....horrible stuff... Stuff you tell your isolated, disbelieving management and they say "I can't believe so-and-so would do that!" Nice to be called a liar...why would I lie? I thought you wanted me to audit work practices?

 

I digress... I blame this on you Tim Z! You linked this thread again and dredged it all up!

Edited by Tony D

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×