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Author Topic: Slow going  (Read 1651 times)
Purplewillie
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« on: August 13, 2013, 12:03:03 PM »

Back from a weekend run to Nancy Green Park. About 250 miles there and home, but like most of the BC interior lots of steep climbs.
Bus runs great, but she is one slow turtle on the hills. I have not checked what injectors are in my 871,but I would think it must be still around the stock 250ish hp. On 8% grades we top the hills at 20mph , but no smoke at all. 70 mph on the flat, but 30,000 lbs and no power make for a slow tour.
140,000 miles on this motor ,no leaks,
Should I look into bigger injectors?
Timing ? Or just keep turtling along?
Mark
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
bevans6
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« Reply #1 on: August 13, 2013, 12:05:42 PM »

I would pull a valve cover and see what you have, as a start.  Then you can make an educated decision.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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Purplewillie
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« Reply #2 on: August 13, 2013, 01:03:43 PM »

N65
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
Purplewillie
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« Reply #3 on: August 13, 2013, 01:04:23 PM »

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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
Taibob
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« Reply #4 on: August 13, 2013, 01:18:17 PM »

 
Mark.

All your symtoms are of a good motor.
Do yourself a big favour and ++JUST LEAVE IT ALONE++.
Its not broke, so don't break it looking for more.

I have the same setup and run the same or more hills from here to Alberta. Just returned from SanFrancisco and the climb from sea level to 7332 ft at Reno, and the 10 mile climb out of Butte Montana and then the Salmo Creston,Paulson,Christina Lake,Elholt,Rock Creek, and finally the Antichrist at Osoyoos. Hope-Princeton has the climb at Copper Mountain,Sunday Summit and Alison Pass. Just a few.

It took me a while to get off the power kick as I thought 28 mph was too slow also.  Guess what , I just pull over for traffic, when convenient and have adopted the attitude that I paid for the spot on the road that I am using. It also gives me the time to thank my old bus [Girlfriend] for getting me to where I am and back again.

The secret is to gear down, run on the govenor,and watch the temps.

Love your bus and it shall serve you well.
Oh, and smell the flowers along the way.

Regards  Bob
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84  mci 9   8v71n N70 Jakes 740 auto   Oliver, BC
treeplanter
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« Reply #5 on: August 13, 2013, 01:28:24 PM »

My bus also creeps up the hills i have the same engine but it's hooked up to a allison VS2-8, 70 to 75 on the flats,looking into propane injection for hill climbing. the steepest grade was our road to home,shifted to first and she made at about 20 mph or less,we have the steepest grade in the county,dirt road, the dust we kicked up was blinding.
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Purplewillie
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« Reply #6 on: August 13, 2013, 01:28:56 PM »

Bob, that is kinda what I was thinking, but I was hoping for 25 to 28 on the hills. I have been shifting my v730 manually , but I still end up unlocked and in 1st at the top. 20 just seemed a tad underpowered .
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
boxcarOkie
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« Reply #7 on: August 13, 2013, 01:33:44 PM »

RULE OF THUMB:  "If you are driving a bus ... You should not be in a hurry."

Nice picture by the way.

BCO-CTA
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LowTide
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« Reply #8 on: August 13, 2013, 01:34:58 PM »

Wish I could help, but I have to say, the scenery is to die for......hopefully one of these days we will be enjoying such beauty Wink
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Mike and Lori
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"1973 MCI MC-7 Challenger"


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Purplewillie
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« Reply #9 on: August 13, 2013, 01:35:28 PM »

Brand new autometer gauges and senders
180 water
Trans climbs to 220/225 on the long hills
Mark
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
Purplewillie
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« Reply #10 on: August 13, 2013, 01:51:53 PM »

Mike, it is beautiful here and we would love to share it.
Don, Thanks  ,
I am no longer in a hurry and my wife loves it.
Spent the first 50 yrs of my life ripping up these roads on bikes and in cars
I recently sold my cbr 1000 , I noticed when I turned 50 my reaction times had slowed significantly. Still have the corvette , just in case I'm feeling too old
This 8v71 runs so nice and its so clean, I'm going to have to leave it as is.
Mark
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
bevans6
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« Reply #11 on: August 13, 2013, 02:20:21 PM »

You could check the timing to see if it's set right, but as a rule of thumb only if you have N65's and they are timed right for your cam gear (advanced or standard) you about have what a natural 8V-71 is going to get.   You can probably fuss around a bit and get a little more, but you won't get 5 mph on a hill more.  That would take a fresh engine and a turbo, and a lot more gears in the tranny...

I second the beautiful picture and great looking bus!

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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wg4t50
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« Reply #12 on: August 13, 2013, 03:03:33 PM »

Assuming the 4104 could navigate those mountains, I would guess the4106 would be much more lively ?
I would have the timing, rack and valve clearance checked by one who understands what they are doing.  Not everyone with a wrench has a clue.

My guess, it is not getting full rack stroke on all 8 injectors atleast, wouldlike to also check the timing pin setting, and of course the valve clearence. Maybe not going full RPM too ?
« Last Edit: August 13, 2013, 06:44:20 PM by wg4t50 » Logged

MCI7 20+ Yrs
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« Reply #13 on: August 13, 2013, 03:34:24 PM »

.....or.......you could move east to Manitoba. They say there is one hill in Saskatchewan, but I haven't seen it yet.....I'm thinking it's a mirage.

My MC7 with N65 injectors and 8V71 with auto is just perfect for here, and it ain't too bad going to Arizona and back pulling a 5500lb toad.

Ditto on the nice photo!
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Mark Morgan    near Brandon, Manitoba, Canada
1972 MCI-7     'PapaBus'  8v-71N MT654 Automatic
Ed Hackenbruch
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« Reply #14 on: August 13, 2013, 03:52:51 PM »

If i remember right i have N60 injectors in my 8v71N and have been down to 20 mph or even less. I just throw on the 4 ways and get in the right lane if there is one, or pull over to the side of the road every now and then if i can and let people by me.....in fact i just did that today and i wasn't even down as low as 20 mph.
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
baker4106
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« Reply #15 on: August 13, 2013, 04:39:16 PM »

I question no smoke.   My 4106 with stock injectors smokes if I try to hold the fuel pedal down while climbing hills.   Is engine staying on full fuel under a load?
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chessie4905
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« Reply #16 on: August 13, 2013, 05:14:41 PM »

   Unless his exhaust outlet has been changed to side outlet instead of rear, he may not be able to tell unless it really smokes. How much is total weight, plus trailer or toad, if any.
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GMC h8h 649#028
Pennsylvania-central
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« Reply #17 on: August 13, 2013, 05:28:49 PM »

I can see smoke from my 4106 when I leave a stop light.   The only time mine didn't smoke or have power was when the fuel filters were plugged.
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luvrbus
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« Reply #18 on: August 13, 2013, 05:58:29 PM »

It is a old trick on the DD to close the air gap on the governor it takes the smoke away because the response time is so much slower and they really never reach full load fuel but will reach the max rpm setting in time it does make one weak when it is done that way   

 If one responds and jumps to 2100 rpm and come back to idle just as fast they will smoke,the governor is the most missed item when it comes to tuning the 2 stroke  

It's to much trouble and most shops just don't bother with it they run the rack,set the valves,Jakes and injectors out the door you go    
« Last Edit: August 13, 2013, 10:42:02 PM by luvrbus » Logged

Live each day like it was your last,one day it will be
Purplewillie
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« Reply #19 on: August 13, 2013, 06:31:03 PM »

Exhaust out the side, no smoke.
No toad,PO weighed it , told me 28,000 lbs.
Mark
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Mark & Char
1976 P8M4905a 8v71 v730
British Columbia Canada
TomC
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« Reply #20 on: August 13, 2013, 08:20:05 PM »

If you have a V730, be sure to shift down to 1st with your foot on the floor-then pull up on the gas pedal about an inch and you should feel the transmission bump into torque converter lockup. This will keep the heat down-anytime you're in torque converter, you're producing lots of heat. I went up over Ebitts pass in 1st the whole way up and back down. In 1st the Jake brake is also very effective. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
RJ
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« Reply #21 on: August 13, 2013, 10:44:18 PM »

PO weighed it, told me 28,000 lbs.

Mark -

Run it across a set of scales yourself, as you would normally load it plus full fuel tank(s), to see what the your weight is, not the PO's operating weight.  Could be significantly different - especially when it comes to setting tire pressures.  (Which you should do after you weigh it anyway!)

IIRC, N65s produce 304 hp and about 800 ft/lbs of torque, N60s 275 hp and 775 ft/lbs.

So your speeds going up, over and around Rocky Top sound just about right.

Now go pick up/download a copy of Aesop's Fable of The Tortoise and The Hare and spend some time curled up reading this classic.  Apply it's thinking to yours when you're behind the wheel of your coach, and you'll have many miles of smiles.

But try to drive it like a BMW and you'll frustrate yourself to no end!

FWIW & HTH. . .

 Wink


PS: Nice pic!
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RJ Long
PD4106-2784 No More
Fresno CA
Jon
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« Reply #22 on: August 14, 2013, 04:25:08 AM »

We've been driving our buses for 23 years and one of the best decisions I ever made was how to drive it.

In business everything I did was rush-rush. I was speeding to sales calls or jumping in my plane trying to do calls in 3 states before the end of the day. When we got our first bus a Prevost with an 8V92 and the 755 transmission with a top speed of around 70 I decided I was done trying to make time. I considered myself on vacation as soon as I was in the driver's seat and nobody or nothing was going to make me hurry up. The thing is called a recreational vehicle and I intended to recreate.

I'm the slow guy in the right lane, and if I have to go up a hill at 55 or 35 I just don't care. I did increase my speed from the original 59 MPH (1800 with the 8V92) to 62 (1500 with the Series 60) but the way everyone speeds past me while I am relaxing on cruise control makes me happy to be able to relax.
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Jon

Current coach 2006 Prevost, Liberty conversion
Knoxville, TN
luvrbus
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« Reply #23 on: August 14, 2013, 04:38:45 AM »

Most people do run their RV around 55 to 60 mph I notice, the back roads are nice for a slower pace on the Interstate I do run close to the speed limit it scares me trucks coming from behind when I am running 55 and they are running 75
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Live each day like it was your last,one day it will be
Jon
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« Reply #24 on: August 14, 2013, 05:01:56 AM »

We've been driving our buses for 23 years and one of the best decisions I ever made was how to drive it.

In business everything I did was rush-rush. I was speeding to sales calls or jumping in my plane trying to do calls in 3 states before the end of the day. When we got our first bus a Prevost with an 8V92 and the 755 transmission with a top speed of around 70 I decided I was done trying to make time. I considered myself on vacation as soon as I was in the driver's seat and nobody or nothing was going to make me hurry up. The thing is called a recreational vehicle and I intended to recreate.

I'm the slow guy in the right lane, and if I have to go up a hill at 55 or 35 I just don't care. I did increase my speed from the original 59 MPH (1800 with the 8V92) to 62 (1500 with the Series 60) but the way everyone speeds past me while I am relaxing on cruise control makes me happy to be able to relax.
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Jon

Current coach 2006 Prevost, Liberty conversion
Knoxville, TN
TomC
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« Reply #25 on: August 14, 2013, 08:22:48 AM »

I had my bus turbo'd, but did not change my rear end gear ratio. Hence, I still cruise at 1850-1900 which is 58-60mph. What the turbo did was to vastly improve my hill climbing capability. I no longer slow down on small hills and only have to down shift on the longest, steepest of grades. I went from 304hp and 800lb/ft torque to 375hp and 1125lb/ft torque. This is the big amount of difference you'd have to do to your engine to see any real difference in performance. Unless you're ready to turbo your engine (it really does wake up the 8V-71!), keep the engine like it is. Don't fool with success. Just kick back and enjoy the scenery. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #26 on: August 14, 2013, 10:20:46 AM »

If you can, look up Francois Roy in Ponoka. It's North of Red Deer, AB.

He is the best DD mechanic that ever worked on my coach. (Clifford is a good friend of mine, but has never worked on my coach)

If you can locate "Frank", get him to check your tune. If he does, you will be amazed at the difference when he is done. He is very receptive to letting you watch, help and will raise your learning curve so much you may become dizzy.

Most can adjust the "rack". Clifford is absolutely right, as usual. The govenor adjustments make the difference!
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Joe Laird
'78 Eagle
Huron, South Dakota
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