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


galderdi

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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.

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  • 2 weeks later...

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 .

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  • 2 years later...

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...

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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.

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  • 7 months later...

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
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  • 2 months later...
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  • 3 years later...

PMC routinely posts up his 'spinny cranks' on FB when he's doing a build.

This thread comes up frequently as a chuckle about the argument that a crankshaft couldn't spin freely with the fingers alone...

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  • 9 months later...

Having read this entire thread, there are several comments relating to the geometry changes the timing chain undergoes when, in effect, 'a head has been cut too much'.  Interestingly, with all the discussion of how to measure and fit cranks and bearings (thanks to PMCRaceEngines!), no one challenged what "too much" equals.

I built an L28 many years ago with an 0.080" cut to the head along with other mods for a mild build (no intention to race this car).  One sad evening while driving on the interstate at night, enjoying those great engine sounds and not paying attention to my coolant gauge...

So on the inevitable rebuild, it took another 0.028" cut to clean the head.  So total head height reduction = 0.108".  To make things even interesting, the block was decked 0.005".  I drove the car about 5,000 miles with the refreshed engine and had no problems at all; and then decided to do a complete rotisserie renovation.  The car has been on the rotis ever since (22 years😩 - one of the many costs of self-employment).

So this year I am resurrecting the restoration, starting with a teardown of the motor and hence, my question: How much is "too much"?

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