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Author Topic: Results of the 8V71 Tune up.  (Read 1759 times)
viento1
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« on: October 24, 2011, 10:23:53 PM »

to recap some of my previous issues.
Low power, poor millage, difficult starting in cooler temperatures, mega slobbering, poor jake performance.

Original thoughts (cost 3k at Waterous)
Sorry, your motor is dusted, your auto trany sucks,

Recent discovery (cost only $2500 including new airbag from Bus's R Us)
I Told Al that I wanted to have him (old school guy) give it a tune up.  The valves were out by five thousands of an inch. The Jakes were completely out. The rack needed adjusting.

The results.
Application of the Jake brakes almost leave skid marks Smiley
you have to sneak up on the start button it starts so fast.
my 0-60 times went from 42 seconds to 38 seconds.
sounds different... noticeable difference
fuel millage has yet to be determined.
Big puffs of White smoke on startup?Huh reminds me of my other bus. What's with the mosquito fog?



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Ok, it's time to go on another road trip.
www.randalclark.com
MC5
thomasinnv
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« Reply #1 on: October 25, 2011, 07:40:13 AM »

It is not uncommon for these old girls to smoke at startup. White smoke at startup is usually unburnt fuel from being cold. As long as it clears in a few minutes I wouldn't worry about it. Clifford (luvrbus) and I just finished putting jakes on my bus, which requires valves be adjusted, injectors be set, and the fuel racks be ran. At startup I had no smoke, which is a first ever. I always have smoke. We set the injectors with slightly less fuel I'm pretty sure that's why. As long as your not blowing blue smoke be happy.
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There are three kinds of people in this world....those that make things happen, those that watch things happen, and those that just wonder what the heck is happening. Which one are you?

1977 MCI Crusader MC-8
8V71N/740
95% converted (they're never really done, are they?)
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« Reply #2 on: October 25, 2011, 12:56:41 PM »

  One thing ive read is that Detroits that are started up cold put a lot of wet unburned fuel into the exhaust until they warm up. If its not worked hard enough to burn that fuel out of the exhaust/muffler, each time its run like that it keeps wetting down the exhaust with fuel, adding more fuel to whats already in there. And each time you start it, it smokes more, and more, and more.

  My understanding is if they are once blown out (run hard) and running clean, you could probably let it idle all day and it wont be much problem, its the cold start/warmup that raises havok.

  As a gear head without Detroit experience, when seeing all that smoke our first reaction is to think its just like any other engine, its got bad rings, bad valve guides, bad injectors, the motors worn out. I wonder how many noobs get talked into a rebuild when there may be little if nothing wrong with their engine that a good tuneup and hard run (or the correct oil) wouldnt fix.

  When I brought mine home, she smoked pretty good the first couple miles, then started clearing out. But I was still seeing some (gradually becoming less and less) for a good 30 miles or more. After that the only thing I saw was some soot before a downshift, or some soot starting from a stop, but no more oil (fuel) smoke. And I have noticed that since its been up here in the yard and the little ive ran it (idling), its smoking more, and longer after a start.
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DMoedave
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« Reply #3 on: October 25, 2011, 06:07:53 PM »

unless you have a fast idle, dont! Drive it or shut it down. 2 strokes dont like idling.
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Chopper Scott
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« Reply #4 on: October 25, 2011, 06:11:49 PM »

Not a better feeling than hitting the start button for 2 seconds and she's runnin!!
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« Reply #5 on: October 25, 2011, 08:27:15 PM »

Not a better feeling than hitting the start button for 2 seconds and she's runnin!!

  Thats for sure. I had a 671 once, you could just about run it dead trying to start it at 70 degrees, and oh Lord did it smoke. But I really wish I could have ran it out and seen if it would have cleared.

  This one I have now, even after out all night in 32 degrees, it started amazingly fast, 2 seconds was probably longer on the button that it needed.
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TomC
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« Reply #6 on: October 25, 2011, 10:19:20 PM »

If your engine is fresh with good injectors-even in 40 degree weather you should only get about 10 seconds of white smoke and then it clears up.  Anything more just means your engine is worn out. 

Both of my trucks that had a 6V and 8V-92TA in them never smoked much on startup.  The most I experienced was at -20 degrees. The 8V-92TA smoked for about 5 minutes then cleared up.  The thing about 2 stroke Detroits-they will run just fine right up to the point of just about falling apart.  Your decision-put up with white smoke and hard starting or overhaul the engine.  And as much as most think-judicious use of ether will make starting easier-and no it isn't like cancer.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #7 on: October 26, 2011, 09:45:48 AM »

  I agree Tom, but quite often with some of these older buses, they had been sitting a long time before we bought them. Many of these, maybe most, were behind on maintenance years ago, now there's lots of gum in the works on top of it. On many of these, the engine isnt smoking or running poorly because its worn out, many just need a good going through and a good hard run, tender loving care.

 

 
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viento1
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« Reply #8 on: October 26, 2011, 11:55:47 AM »

Appreciate all the comments, I look forward to to the first hard run and will give a full report on fuel consumption and slobber. My hope for a noted improvement.

Is it worth putting a hydronic heater? or just plug her in and use starter fluid?
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Ok, it's time to go on another road trip.
www.randalclark.com
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TomC
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« Reply #9 on: October 26, 2011, 01:30:40 PM »

Hydronic heating is expensive, complicated and requires frequent maintenance.  Electric block heater is cheap, simple and requires no maintenance.  Can you quess which I like better?  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
viento1
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« Reply #10 on: October 26, 2011, 02:58:07 PM »

done, Tom... thanks for talking me down(again)
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Ok, it's time to go on another road trip.
www.randalclark.com
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« Reply #11 on: October 26, 2011, 08:27:47 PM »

Electric block heater needs no starting fluid.

My coach engine always feels better on the second day of the trip.

Like the thoroughbreds they were, they GOTTA RUN!

That being said, don't fret about idling it either,

it'll clear the next time you get out on the highway and stretch it out...

happy coaching!
buswarrior
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Frozen North, Greater Toronto Area
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