I'm looking for someone who can check/reset the governor on my 1978 MCI 8v71. It has never worked since I bought the bus. Never a big deal as long as I was driving now with son inlaws I worry! I'm in central Texas by Brownwood, but can travel within reason. If I can get governor and bus ac recharged id be a happy bus nut!
Which governor? The one on the air tank or the one on the engine?
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Quote from: Dietrichfarms on March 04, 2017, 06:36:30 AM
I'm looking for someone who can check/reset the governor on my 1978 MCI 8v71. It has never worked since I bought the bus. Never a big deal as long as I was driving now with son inlaws I worry! I'm in central Texas by Brownwood, but can travel within reason. If I can get governor and bus ac recharged id be a happy bus nut!
Quote from: Zephod on March 04, 2017, 06:55:08 AM
Which governor? The one on the air tank or the one on the engine?
Pretty sure he means the one on the engine!
Governors on the AIR system are not usually a problem.
;D BK ;D
Quote from: B_K on March 04, 2017, 10:39:48 AM
Pretty sure he means the one on the engine!
Governors on the AIR system are not usually a problem.
;D BK ;D
I'm puzzled because a governor on an engine does little more than limit maximum road speed. My bus has the governor set at 56 on the flat. I'm ok with that so I don't see any point in changing it. It makes me slower uphill but that's the only issue and it just plain doesn't bother me.
The governor on the air tank limits pressure to 125psi on most busses with the emergency relief valve releasing at 150psi. Now I'm pretty sure I'd want THAT governor working.
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Zephod
"I'm puzzled because a governor on an engine does little more than limit maximum road speed."
Is where your wrong!
See these old Detroit 2 strokes in these OVER THE ROAD COACHES truly are different animals than what you are used to in your skoolies!
I ain't try'n to put your skoolies or the knowledge of them you have down, just pointing out there is a LOT you don't understand about the BEAST of the over the road coach that most of us on this board own, know and work on.
The governor on a two stroke does two things it controls wide open throttle RPMs both under a load and w/o out a load! (it does NOT control road speed, it controls ENGINE speed)
And it is a very tricky piece to properly adjust and if one gets it wrong BOOM there goes a expensive lesson to the owner of said engine!
Yes Skoolies have governors that actually get signals from the speedo and limit the road speed but these big DD's are a totally different animal than what you'll find in ALMOST any skoolie.
;D BK ;D
I erred... the governor on my dt466 governs rpm. The governor on the Thomas I drive for work has a speed governor.
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Quote from: Zephod on March 04, 2017, 11:11:10 AM
I erred... the governor on my dt466 governs rpm. The governor on the Thomas I drive for work has a speed governor.
Exactly! But even that DT466 is a different animal than a real Detroit 2 stroke!
;D BK ;D
Also if not set up correctly a two stroke will not start reliably, the fuel will not meter properly and so forth,,many control items on a 2 stroke depend on a correctly set governor.>>>Dan
Have you checked da book for 8v71. I replaced my engine with one that the governor was disabled and it worried me. I read the book and tried resetting the governor but didn't work right. I reread dabook and followed it carefully and the second time I got it set at 2150 rpm. I then increased the speed to 2350 to help when I shift. One thing they don't say is when you remove the governor cover and then check the gap at 1000 rpm it will throw oil all over. I have a 4106 with a stick shift and live in Michigan.
Quote from: baker4106 on March 04, 2017, 03:32:35 PM
Have you checked da book for 8v71. I replaced my engine with one that the governor was disabled and it worried me. I read the book and tried resetting the governor but didn't work right. I reread dabook and followed it carefully and the second time I got it set at 2150 rpm. I then increased the speed to 2350 to help when I shift. One thing they don't say is when you remove the governor cover and then check the gap at 1000 rpm it will throw oil all over. I have a 4106 with a stick shift and live in Michigan.
The DD 2-stoke uses a somewhat complicated governor system. The governor gap has to be right before you can proceed with the injector rack adjustment, then there is the high speed and idle adjustment, and lastly the buffer screw. If you have Jakes, that is another adjustment. Anyway, if you don't get everything right, you will have low power
Did I miss the valve and injector height adjustment??
--Geoff
Quote from: Geoff on March 04, 2017, 05:17:18 PM
The DD 2-stoke uses a somewhat complicated governor system. The governor gap has to be right before you can proceed with the injector rack adjustment, then there is the high speed and idle adjustment, and lastly the buffer screw. If you have Jakes, that is another adjustment. Anyway, if you don't get everything right, you will have low power
Did I miss the valve and injector height adjustment??
--Geoff
Or they smoke like a train too
Guess I did a miracle because mine worked. Engine ran ok but governor didn't cut in. I found the gap was too wide and when I got it right I could then adjust the speed. Didn't affect the engine performace at all. That was 7 years ago and I didn't touch the rack.
Quote from: Zephod on March 04, 2017, 10:46:17 AM
I'm puzzled because a governor on an engine does little more than limit maximum road speed. My bus has the governor set at 56 on the flat. I'm ok with that so I don't see any point in changing it. It makes me slower uphill but that's the only issue and it just plain doesn't bother me.
The governor on the air tank limits pressure to 125psi on most busses with the emergency relief valve releasing at 150psi. Now I'm pretty sure I'd want THAT governor working.
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I apologize for the comment on an older post, but are you are referring to the governor on the air compressor?
And (non-quote specific) I would love to know how anyone with a DD 2 stroke engine governor can get the engine to start and idle without the governor working? It affects everything...at least on my engine. Again, my apologies...SORE subject, but one that sure gave me quite the education.
Governor doesn't control idle just top end speed. If you want more ground speed just make sure you don't go over about 2450 rpm. My 4106 runs just over 80 mph at 2150 rpm. Ground speed is controled by the rear end gearing. I owned a 4104 in the 70's that ran the same as my 4106.
Quote from: baker4106 on March 11, 2017, 05:25:47 PM
Governor doesn't control idle just top end speed. If you want more ground speed just make sure you don't go over about 2450 rpm. My 4106 runs just over 80 mph at 2150 rpm. Ground speed is controled by the rear end gearing. I owned a 4104 in the 70's that ran the same as my 4106.
What controls the idle speed ? if not the governor setting
It definitely controls both ends of the rpm range.
It has been mentioned before that I could possibly have a strange bus (my words)...but if my engine governor settings are not correct, it causes issues ranging from the output shaft to the ability to simply start the engine...all the systems I thought of and a couple I didn't (at that time).
If you read da book you will see there is an idle adjustment screw.
Quote from: baker4106 on March 12, 2017, 05:08:20 PM
If you read da book you will see there is an idle adjustment screw.
where is it located ?
Quote from: Geoff on March 12, 2017, 08:03:41 PM
Underneath the bed!
--Geoff
next to or beside da book?
wtf is da book?
Da book is next to the Bible and sez Detroit Diesel on it. Great bedtime reading after religion.
--Geoff
I need audio books and play it in my sleep. Be a Detroit meckineck before you know it.
Quote from: eagle19952 on March 12, 2017, 07:03:28 PM
where is it located ?
It's on the carburetor right next to where the linkage hooks up! ;)
;D BK ;D
Don't forget, any time you adjust the idle it's a good idea to replace the muffler bearing.
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Quote from: thomasinnv on March 13, 2017, 08:11:09 AM
Don't forget, any time you adjust the idle it's a good idea to replace the muffler bearing.
Unless it has the new ceramic muffler bearings already installed they last like 30 times longer than the teflon ones! ;)
;D BK ;D
Quote from: B_K on March 13, 2017, 08:04:11 AM
It's on the carburetor right next to where the linkage hooks up! ;)
;D BK ;D
OK, my first reaction is to start laughing? ;D
I'm in Florida and my book is in Michigan so I can't send you the instructions. The idle adjustment is on the top of the governor. Setting the max rpm is easy if no one has miss adjusted the insides. Seeing how everyone just wants to make remarks, I won't post again. Send me your email and I will get back to you. Larrydbaker@aim.com. good by to everyone else, too bad you didn't want to help him.
There goes another pissed off customer
Quote from: Geoff on March 13, 2017, 07:07:20 AM
Da book is next to the Bible and sez Detroit Diesel on it. Great bedtime reading after religion.
--Geoff
oh...in this part of Alabama, we call it the Good Book and THE book...who knew?
Quote from: baker4106 on March 13, 2017, 03:41:02 PM
I'm in Florida and my book is in Michigan so I can't send you the instructions. The idle adjustment is on the top of the governor. Setting the max rpm is easy if no one has miss adjusted the insides. Seeing how everyone just wants to make remarks, I won't post again. Send me your email and I will get back to you. Larrydbaker@aim.com. good by to everyone else, too bad you didn't want to help him.
Sometimes these posts get to the ridiculous stage. Mr. Larry Baker, YOU are the one who said look at "da book". Which is what 90% of the posters on this board need to do, including you, who doesn't even know that the idle adjustment IS NOT on the top of the governor.
Adios, mi amigo.
--Geoff
Thanks everyone for all the input. What I'm really looking for is recommendations on who are where to take my bus to get the governor set. Like I said I'm in central Texas but can drive the bus to a location for work. Thanks again for any help.
If you are ever in the Bullhead Az or Laughlin Nv area stop by and I will check it for you,In Texas try Stewart and Stevenson they still work on 2 strokes.
What makes you think the governor needs resetting ? once set they usually never need to be reset again till you run the rack.
All the LS-DW governor does on your engine is limit the top RPM and the idle it's not a variable speed governor
Clifford-- you are right, but how do you know the governor, rack, valves and injectors were set right to begin with?
One of the first things I do when I work on a DD is back the idle screw off, put the rack in the full fuel position, and see how far off the rack is and if it is pushing against the governor. If it passes that test I know it was set right.
--Geoff
I don't know what he is after Geoff ,I do the same with backing the idle screw out.If he thinks holding the pedal in 1 position and the engine will keep the same rpm up on a incline he can forget that with the LS governor
I have never had this engine come up against the governor. on at least two occasions when I wasn't paying close enough attention I ran rpms up past 2300.Like I said before bus starts and runs great I just don't like that it will over rev if you hold your foot down. I wont let anyone else drive because of this. I had heard of Stewart and Stevenson in Dallas/Denison, I will give them a call. Thanks Everyone
It maybe set on 2500 rpm no load you see that see that setting a lot on a 8v71
I passed a truck the other day and was doing 90mph @ 2900 rpms. The 6V92TA took it okay, but my speed was not intentional.
--Geoff
Yes that was me on I-10 out of Fort Stockton Texas ran my 8v71 up like that, not intentional. That's why I would like to get governor set.
At the strong risk of being a day late and a dollar short, has anyone posted the actual instructions for setting the governed high idle speed on a MUI engine yet?
http://miscpartsmanuals3.tpub.com/TM-9-2815-224-34-P/TM-9-2815-224-34-P0502.htm (http://miscpartsmanuals3.tpub.com/TM-9-2815-224-34-P/TM-9-2815-224-34-P0502.htm)
You can ignore the bits about the turbo cover and you can do it if you're not a soldier, this is just the PUB for military engines on-line. It's for an 8V-92, but 8V-71 is identical except for no turbo. In the simplest of terms, you take the cover off the adjusting spring stack (what I call it, I don't know it's real name) that is about 3" long and runs along above the valve cover from the back of the governor on a 8V-71. You loosen off the lock nut (needs a special tool or some ingenuity), you back off the adjuster five turns, you start the engine, you give it full speed ahead on the speed control lever and you screw the adjuster back in until you reach your desired speed. Helps to have someone to read the tach for you. Then you lock it down with the lock nut. The "adjuster" is AKA the "high speed spring retainer". You are adding preload to the spring that controls the maximum no-load speed of the engine. By backing it off you set the maximum no-load speed to "not much" and then you add it back in to where you decide you want it (or if you are a trucker, as fast as you dare, or if you are a soldier, where the Sergeant tells you to set it). There is something called "droop", which is the difference between no-load maximum speed and full load maximum speed. Typically droop is around 150 RPM, but varies and is (as far as I know) not adjustable. If you decide you want 2300 rpm maximum speed at full load (which is what I want, personally, on my engine) I would set the no-load to 2450 rpm (which is what it came set at, being an ex-NATO tank engine) and I checked it, but did not adjust it, because it was dead on. You can then check idle, buffer screw, starting aid, and all the other stuff if you want to. It's in the PUB.
Again, apologies if I am being redundant in the thread.
Brian
Governor droop is determined by how much wear and how much slop you have in your governor weights and rack linkage. A Detroit engine with no slop and the governor gap set correctly will have as little as a 50 RPM droop, to maybe none. You need a dyno to check the governor droop as it is checked at full load, something you can't do if you are driving.
I set top no load at 2350. Mine is set at 2900 rpms because my Jakes came off a military engine with oversized governor parts to run at higher speed. I drive it at normal speeds, but sometimes forget when passing somebody.
--Geoff
Just remember how fast those valves are moving... twice a fast as a four cycle.2900=5800.Some valve float and a keeper dislodges.....BANG!! Blam,, blam,blam. Junk.
Geoff, I got my droop number from the engine manual for a M110 howitzer, which is what my engine was originally used in. I copied the specifications when I wrote up my engine swap project. That's all I know about droop! :) Actually, reading the spec again it quotes maximum hp at 2300 and max no-load at 2450, and I assumed that was the droop. Could well be a mis-interpretation on my part.
Here are the spec's:
ENGINE 8V-71T 7083-7395
Manufacturer Detroit Diesel Engine Division, GMC V-8, compression-ignition, liquid cooled
Type Turbocharged, two-cycle diesel
Model (7083-7398) or (7083-7395) 8V71T
Weight, Dry (as installed) 2,442 lb (1,107.7 kg)
Number of Cylinders 8
Displacement 568 cu in. (9,308 cm3)
Bore 4.25 in. (10.8 cm)
Stroke 5.0 in (12.7 cm)
Compression Ratio 17:1
N-80 Injectors
DW-LS governor
Horsepower, Gross Brake (at 2,300 rpm) 405 (302 kW)
Horsepower, Net Brake 345 (257 kW)
Maximum rpm. No Load (governed) 2,450 rpm
Idle Speed 650-700 rpm
Droop only accrues under a load,I just got a 525 hp 8v92 off the dyno set @ 2250 rpm it has a rebuilt governor and all new linkage. I get no droop @400 hp, 25 @425hp the short version is I get 125 droop @525 hp with 1580 ft lbs of torque and I cannot get that droop out of the engine I've tried for 2 days any answers ?
Quote from: luvrbus on March 24, 2017, 08:57:47 AM
Droop only accrues under a load,I just got a 525 hp 8v92 off the dyno set @ 2250 rpm it has a rebuilt governor and all new linkage. I get no droop @400 hp, 25 @425hp the short version is I get 125 droop @525 hp with 1580 ft lbs of torque and I cannot get that droop out of the engine I've tried for 2 days any answers ?
Do you have a yield link or a solid link in the governor linkage? You want a solid one.
--Geoff
To me droop makes a lot of sense intuitively. At no-load, the governor is shutting off fuel at the injectors to limit speed, and the injectors are only delivering minimal fuel to develop the quite small power needed to overcome the internal load of the engine - not much. At full load the injectors are delivering full fuel right up to the point where they back off to limit further acceleration of the engine, hitting the governed limit. Totally different operating conditions. The dyno will pull down the engine speed as far as it can with increasing load (that's how it measures the torque twisting the brake load cell) until it reaches a balance point where the load and the power equal each other, at the governed RPM. I suspect that if you are truly loading the engine fully, it will not be accelerating and so the governor isn't what is limiting the RPM, the dyno brake is. For full power the governor isn't limiting speed by backing out fuel. At less than full power, the injectors can deliver additional fuel to reach a higher RPM so the governor is what is limiting speed. My dyno experience is with gasoline 4 stroke race engines, mind you... :)
How do you measure droop at 425 hp on a 525 hp engine? Lower RPM? Set the engine at a speed, and increase the dyno brake to see what maximum power you can pull at that speed?
The short answer is that you run the DD2stroke on the dyno at your top no load RPM and increase load until you are at HP for the size injector according to the book. The rpms tell you what the actual droop is. You also use a screwdriver in the buffer screw hole and check travel every time you increase the load until at full load the screwdriver bottoms out pushing against the governor link. You have to be careful not to increase the load past the advertsed HP after the linkage bottoms out to get an accurate droop
--Geoff
So you run it at max no-load, load it to the setting you want to achieve based on specification of the engine, and see how far it droops when you achieve that HP. If you have an engine that could reach 525, and you only load it to 500, it would droop less and stay closer to max no-load. If you loaded it to 550 you would pull it down farther and have more droop (if you could load it that high).
Race engine guys do similar things to get great HP numbers. What we did is sneak up on it from below, run the engine at roughly 500 rpm steps from say 5,000 to 8000 rpm, and bring the load up to where it balanced with the engine at full throttle at that rpm. Another way to do it is to let the brake pull the engine down from a high rpm to a low rpm. It takes more brake torque to pull the engine down than to just barely balance it, so if you want a really big number you pull it down hard and boom, 15% more power than you actually have. But it's on a computer readout, so it must be right... ::) Depends if you are selling engines or winning races. the only dyno that really counts is the back straight on the track, or that hill in a bus...
The 8v92 wasn't done on a water brake dyno, it was a new computerized Eddy Current dyno 31 sensors and told all
Quote from: luvrbus on March 24, 2017, 02:17:20 PM
The 8v92 wasn't done on a water brake dyno, it was a new computerized Eddy Current dyno 31 sensors and told all
So if Eddy Current told all, what was the cause of your 125 RPM power droop?
--Geoff
Quote from: Geoff on March 24, 2017, 06:53:32 PM
So if Eddy Current told all, what was the cause of your 125 RPM power droop?
--Geoff
It tells and shows you on the screen or you print out a 6 ft long graph where the droop begins it is not quite smart enough to tell you how to fix or stop the droop that is why I asked the brains here and other places.I would like to have 0 droop
The governor weights might not be equally adjusted. If you use a screwdriver to spread the weights to set the governor gap, check/adjust one weight, bar the engine over and see if the other weight is the same gap. A lot of times they are not equal and you have to pull the governor, pull the weight assembly off, check for slop, and lastly grind the stops so when you spread the weights they touch the spool exactly the same. Most shops would not bother. Also if you need the bronze bushings for the weights I should have some left. I am going by Kingman Thursday morning and like to stop and visit. Call me at 928 771 0045.
--Geoff
Geoff, I will give you call right now I am out of service anyways a friggn handle came out of a grinder and got loose and I look like have a zipper on my hand
A sure sign of OLD AGE!!>>>Dan
You ain't old if people laugh when you fall down.
If they come running over . . . . you are officially old ;D