Tech "?" What is a rack and how...

[Singing Land Cruiser]

  Ok guys, Help me out hear. What is a rack and how often does one Run one. Laymans terms please. Thank you, M&C

[Len Silva]

Running the rack means dropping all the balls into the pockets without missing any, and without dropping the cue ball. A true professional drops them in numerical order.

Told you I need a life!

[Singing Land Cruiser]

  Thanks Len. M&C

[Dallas]

It's a simple job, requiring only a pair of vice grips and a cheap feeler gauge and can be accomplished in a half hour by anyone conversant with walking on two feet and chewing gum at the same time.

Set the exhaust valves, set the injectors, set the different governor adjustments, adjust the idle, set the buffer, reset all of it all over again a few times and it's done!

The several thousand dollars worth of tools I have just for that purpose really aren't needed at all.

[poppi]

Some picture may help

  http://www.tpub.com/content/construction/14264/css/14264_187.htm

go backwards and forward in the links and you too can be a gear head

Skip

[Blacksheep]

Not at all what I what I was thinking of! I mean, you all have seen my neighbor right?   

Ace

[JohnEd]

M&C,

I didn't read your post as "actually looking for instructions" but more of a requirements inquiry and background.  Well I never done one neither, but I think I can answer your question to the level you seem to have intended.  At ant rate....I am certain I can answer any question to MY satisfaction.

The "rack" is slang in Diesel Land for the "VALVE TRAIN ASSEMBLY" located in the cylinder head.....top of the engine.  In cars, there are only intake and exhaust valves to worry about.  In the two cycle there are only exhaust valves to worry about as the air intake is in the ports in the cylinder side wall BUT you also have INJECTORS, IDLE SPEED and other stuff that needs to have clearances set to thousandth of an inch tolerances.  On cars you need a simple set of wrenches and a FEELERS gauge to do the job.  On the DD2 stroke you need special feelers gauges AND special wrenches AND special experience doing the job.  It ain't rocket science but it is a load more complicated than a valve adjustment in a car world engine.

I have read that, after being done correctly, it need not be done for the rest of the engines life.  That was not in a DD engine manual that I read that.  In our case it would seem to be once in our lifetime per engine we own....max.  If I purchased a bus that had a D engine I would have already had a DD dealer check the engine and I would know if it needed a valve adjustment and a bunch of other stuff for $300 or so.  If you engine maint records are complete you will have evidence of any repairs that involved "Running the Rack".  No paper work?  Why do you own that?

There is a problem here.  D mechs are like gunsmiths:  all of their work involves recreational use on the part of the owner.  Nobody makes a living from their gun anymore than anybody really NEEDS a bus.... in the opinion of some shops.  Just getting an estimate on running the rack would seem to highlight those scoundrels  that will overcharge us.  There are a number of people on here, Dallas in particular, that can tell you how many labor hours are needed to do that job.  I think it was 4 or 5 for an 8V71 but I am not certain.  Most of us knew that the estimate of FOURTEEN hours was abusive as that made running the rack a ONE THOUSAND FOUR HUNDRED dollar adventure for labor alone.  That is only a grand more than you should expect.  They know that they are the best judge of whether your engine needs that service and they shaft you for your insolence or for owning a "toy" that expensive...either one.  I have read a lot of posts where people were quoted exorbitant charges.

Good luck with this.

John

[Van]

"Rack em up"

http://www.youtube.com/watch?v=D_bOO6XJXrQ

[poppi]

  As a side note..........please do note that setting the rack according to just specs is not always enough
especially if you have a DD virtuoso....balancing the injectors is more than using a feeler gauge.

Some one who is good can make a DD hum any tune you want. Cold cylinders are bumped up hot are
backed off.................Just because it is by the book gets you in the ball park being good gets you box seats


   Skip

[Blacksheep]

Gee Van if ya'll wanted Video's I could have maybe talked my neighbor into doing one! What do you think?

This neighborhood sure hasn't been the same since she moved in last month!

And you know what? You DO meet the nicest people on a Honda! 

Ace

[JohnEd]

What Skip said:  There still is no substitute for experience....Thats where Dallas comes in....and others, I am sure.  But they aren't the last ones on the planet.  The only way to get experience is to do the work and that should be performed under the supervisory watchful eye of a master.  Its just like sex, Son, or even high explosives.

John (always get two estimates) Ed

[TomC]

The rack refers to the fuel rack which is the linkage inside the valve cover that operates each cylinders fuel injector coming off the governor.  It has to be balanced so all injectors are fully open at the same time-which is the most important time to be balanced.  Some try to adjust the rack so it idles smoothly-then you loose some wide open throttle smoothness.  Besides adjusting the rack travel, there is the gap at the injector rocker arm to be adjusted, adjust each of the 4 cylinder valves per cylinder along with adjusting the bridge on each of two of the valves, adjusting the jake brake (if equipped), adjusting the upper and lower rpm limits on the governor, adjusting the buffer to get a smooth idle without the engine rolling up and down (some like the sound of a Detroit idling up and down), adjusting the fast idle circuit-then making sure all works well together.  Usually a job for those that are familiar with all the nuances involved with "running the rack".  Good Luck, TomC