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I found a company with several 8V71 LH rotation engines for sale.  I'm intending on buying one of these engines.  I asked what injectors are installed and they have 7E55 injectors.  I am only familiar with the N60s, N65 etc.  My engine has N60 injectors and it's rated for 270 hp.  Do the 7E55 injectors have the 318 hp rating?  The company thinks they are 318 hp rated.

Thanks!

Mark

55 injectors have a 255hp rating with 675lb/ft torque.  Very long lasting with good fuel economy and can be driven all day long with your foot on the floor.  Good Luck, TomC

TomC, would OneLapper be happy with the 7E55 injectors in his Bus Conversion?  I have no idea, but years ago our old American LaFrance fire apparatus had N90 injectors.  8V71N 350hp, 900 tor..

However, they were way too big.  The Engineer (operator) had to quickly learn to "keep his foot out of it" until the mill had revved way up..or...clouds of black smoke was the result.

Anyway, The State of Commiefornia (California) made the shops reduce the injector size to something manageable.  Dunno what size.  Smog laws.  1976 or soss.  Ancient history.  :) :) :)

Thanks TomC, I'll have to figure out what it'll take to get the 7E65 or N65 injectors installed.  Found them online for $50 each for rebuilt units.  Waiting to hear back from DD dealer on the differences of the 7E series injectors versus the N series injectors.  I think I'll need a bit more than 255 when pulling my trailer, but who knows what I have for hp now!!!  255 might be a huge improvement!

If I'm going to spend the money and time to install a fresher engine, I may as well build it up to the 318 hp rating.  Now would be the time when it's sitting in a cradle mounted to a pallet.  I'll also advance the cam timing at the same time.

I'm getting 10.8 mpg at 65 mph on a long trip, and 7.8 pulling a 7500# enclosed car trailer.  Actually, hp is fine, I'd like another 5 gears!

Thanks,

Mark
4106

More horses require more feeding . . .  Something to keep in mind . . .

If you travel at the same speed with all other conditions the same....both size injectors "should: give you the same MPG.  It is only logical as it takes the same amt of fuel to make the same HP in both cases.  If you don't actually use the additional fuel that a larger injector "can" deliver, it should deliver the same efficiency.  Neat logic, huh?  I have been told that it DEFINATELY does not work that way and that no matter how careful the driver is he can't match the efficiency of the two unless he floggs the smaller injector equiped engine and feathers the big injector equiped item. 

Any one care to comment on that?  I accept the "experts' advice...make no mistake.  Still, I got no rationale with the advice.

Thanks,

John

Onelapper you will get 318 to 304 HP from the 7E65 injectors in a 8v71 818 ft of torque at 1400 rpm The 7E55 are in the 250 HP range don't think you would be happy with the performance of the 7E55 injectors pulling a trailer

Injector size ain't the only thing changed. There are other things that were also changed - timing? power curve? efficiency curve?


If it was so simple, why wouldn't all engines come with the same injectors & simply use throttle stops to limit power?

DD just faxed me over the build sheet on the engine I'm interested in.  It originally came with C60 injectors and later had 7E55 injectors installed to save fuel.  Built on 12/17/1981

Does any know how to read these spec sheets?  I'll post the info tonight and hope someone can decipher the data.

Mark

Mark,
     I doubt that you really want the 318 hp set up.  To get 318 hp you have to go to 'advanced' timing which has the unfortunate side effect of raising the torque peak from 1200 rpm to 1400 rpm.  The transmissions in the GM buses are designed around the 1200 rpm torque peak and with the 318 setup many small uphills will force you down into a lower gear than you could pull with the lower power setup.  With 'standard' timing n60 injectors are as good as it gets.
Regards
Jerry 4107 1120  (standard timing and n60 injectors)

Hi Jerry.  You bring up a good point.  I'm giddy with idea of having a complete engine on the ground, easy to work on, so I figure now is the time to put the engine together the way I "think" I want it.  I know about torque, my TDI Jetta has 100 hp, but 185 tq.

I thought that these coaches came with the 318 hp setup.  I don't really mind the downshift because with the trailer I'm more than likely downshifting to third and holding it at 50-55 mph even if I'm at part throttle.  I wish I had a tach because I have no idea what the governor is set at.  I do know that I had it up to 80 without hitting it.

Is there anyone out there with a 8V71 running N65s with advanced timing?  In a Coach?  I'd love to get some feed back!

You can get a hand held tach. at Harbor Freight real cheap now, around $60 if I recall. Really good for setting your iddle and no load max. rpm on the governor.

JC

One of the side effects of going to advanced timing is to narrow the power band a bunch. The "so-called" 318 is really a 304 with standard conditions. The reason that the trucks had this setup is because they had the gears to pick the right ratio.

With a four speed transmission, you need a very wide power band. The standard timed C or N60 provided this. And I don't believe that I've seen a case where the N65 advanced timed bus got the fuel mileage that a standard timed one does.

Ask a trucker if he works his Detroit two stroke much below 1500 RPM. I would be surprised if you don't get told "You don't lug a Detroit".

For what it's worth.

Tom Caffrey

Here is some of the data on the "Engine Equipment Record"

Model:  7087=4021  APPL:  332S  Min Idle RPM:  500   MaxNL:  1950   MaxFL:  1800
CamTim:  STD GT-STD CAM   Then a bunch of Customer Spec Info, ship date, sold to, etc.

Equipment                PBT         UPC GROUP

ACC DRIVE               153          06X04 0291
AIR BOX DRAIN          144         06A01A0200
BAL WT COVER          29           06J01 0083
BLO DRV SHAFT         27           ...............
BLOWER                   245
C/S RD TRAIN            89
CONN ROD/PSTN        170
CRANKSHAFT             69
CYL BLOCK                35
CYL HEAD                  91
DIPSTICK                  816
ENG LIFT BRKT           139
EXH MANIFOLD           376
F/HSG ADAPT            40
F/W HOUSING            531
FLYWHEEL                 940
FUEL PUMP               174
GOVERNOR                1484
INJECTOR                 113
INJECTOR CONT         255


It goes on and on, oil cooler oil dist oil filter oil pan oil pressure regulator oil pump, rocker cover, tach drive, thermostat etc.


Does anyone know how to read this info?

Mark

Aren't those numbers for a fast parts reference I believe the parts book breaks in down from that number for the engine application.Someone correct me if I am wrong but the model number and block number shows that block can accept a after cooler for a turbo.Sorry I could not be of more help but it takes a master parts book to tell what the group numbers stand for.

It appears that the PBT number is the factory option code for a particular item the engine had.  Example:  INJECTOR 113 is for a C60 injector and that means the engine was delivered from the factory with that injector, not the 7E55 injectors that are in it now.  I found a website that sell parts that list application by the PBT number!

Mark

The model no. is 7087-4021.  The last four number are for:  4=Left hand rotation  0= N  21= Model Variation.  Does anyone know what the N is for?  As in 8V71N?  My current engine is 4220 which 4=Left hand  2=4 valve head  20= Model Variation.  This other engine has a four valve head, but the code is 0 for N, not 2 for 4 valve head.

Hmmmm.....

Mark

Quote from: OneLapper on September 02, 2008, 08:40:03 PM
The model no. is 7087-4021.    Does anyone know what the N is for?  As in 8V71N? 
Mark

This is about 1/2 guess, but I am thinkin' N as in 8V71N which means NORMAL Aspirated (supercharger) as opposed to 8V71 TA which has Turbo charger and aftercooler in addition to supercharger.  Jack

Hi Jack,  I also assumed N is for Normal, but then Normal must also include the four valve heads.  The problem is that there are so few people that still work on these engines, and even fewer that are knowledgeable about the option codes, build sheets, the differences of injectors, cam timing, etc.  At this point, I'd be happy to pay some for an hour of their time just as long as they were able answer my questions.  I called the local DD dealer (which I have a resale charge acct with, so they are familiar with me) and they have one tech that works on the 2 strokes.  When he called me back and asked my question "what are the differences between 7E60 and C60 and N60 injectors?" he didn't know.  He said he only installed what was spec'd on the DD Engine build sheet for the particular engine he was working on and that their shop did not "modify" engines with bigger injectors and changing cam timing.   Alrighty then.  He then suggested I talk with the parts dept, who suggested I talk to service.  Fair enough.  I thanked them for their time and hung up.

I'll figure all this out, it'll just take me a bit longer.

Mark

I love this topic.  Here is what little I can provide:

I have a 1983 MC9 with an 8V71N and 5 speed manual.  The engine numbers are SN 8VA 430520-1 and the model is 7087-7527.  I just had the engine rebuilt professionally with 7E65 injectors.  It runs much better.  I am used to big HP engines like a Cat 3406B,C @425+.  One cannot expect to get Cat performance out of 2 stroke Detroit, but for what I do with it, I will live.  It does fly except for on hills.  Yes it does smoke black under heavy fuel.  This just means you gotta learn how to drive it to maximize pulling while minimizing smoke.  I wish it was more powerful but I also wish it was Cat 3406B ATAAC with a 13 speed and vertical exhaust.  If I find ever find a 8V92TA with an auto all ready to go, I may do it but it is not a priority.  The only thing I would like to do is actaully get the supercharger more air.  I think, and I could be wrong, but if I got it more air it may not smoke as much and have just a smidge more power, but all things being equal I would rather spend money on inmotion satellite and a leather J lounge.  Black smoke is unburnt fuel right?  If I get it more air, won't it help burn the fuel?  If I can help anybody please let me know.

O32, change the gear ratio on your blower it will help there are several different ratios for the blower from a DD dealer

Hey Makemine:

I have never heard of that, but I will investigate.  Sounds great!  Thank you.

O32...

032, the last four of your model number indicate the following:  7 = Right hand Rotation with starter on the lower Left and oil cooler on the lower Right, as view from the flywheel.  5 = Customer spec'd engine configuration.  27 =  is the specific model variation number.  To get all the details of the engine build as it was delivered by DD, you can ask the parts dept at a DD dealer to fax it over to you.

BTW, can you find out what the cam timing was that your engine builder used?  I'd be interested to know if it was 1.496 which, interestingly, is the same timing spec'd for the 7E55 injector.  The 7E60 injector is 1.500 for cam timing.  You may be able to reduce the amount of smoke if the cam timing can be advanced to correct setting, assuming that it hasn't been done.  I should certainly hope that your engine builder advanced the cam timing.  Go ahead, call him and ask!  We all want to know!

Mark

Onelapper; the engine build on a 30 year old engine is not going to be the same if it had stayed in the DD dealers network it's entire life it would but the engines have been changed from right to left, left to right, cams, liners and pistions,valves ,fuel pumps,governors you name it it has been done to these engines and every DD mechanic has a box full of timing gauges that he uses for what he thinks gives the best performance.But the build sheet is good reading material, you will not find 1 in 100 that is built by the original sheet there is probably 40 or more different injectors made for the 71 series  fwiw

twostroke, I think you're probably spot on.  I can't imagine that too many engine have existed as they were originally built.  BUT, as the owner of John Deere dealership, I can say that 90% or more of our institutions and municipalities buy Deere parts for their equipment.  We rebuild several engines a month for customers that need their equipment to be as close to original as possible because it may be repaired at different dealers for whatever reason.  We go by the tech manuals to the letter to ensure the job is done correctly.  Besides, I have to put my money where my mouth is because I warranty that job.  One of my part time techs works for the local transit bus company.  They do zero engine rebuilds.  They all get sent out to engine dealer.  He'll be the first to tell you that he's a parts swapper!

I'm still waiting for a call back from a DD tech that is reputed to know the answer to my questions on injectors.  Will update when I talk to him.

Mark

Mark, you being a Deere dealer you shold love your 8v71 fwiw Deere cast all the blocks and heads for the 8v71

I called my builder, he is going to talk to the mechanic at lunch to verify the cam timing and also about the blower drive ratio.  You guys are money!

I spent some time on the phone with jobbersinc.com outta PA.  Their parts guy was very helpful.  Here is a synopsis of his answers:

C series injectors (ie:C65) were installed in engines delivered to California and New York, or other major cities that had smog laws.  These injectors, in some manner, decrease emissions.

N series injectors (ie:N65) were installed in engines that were used for industrial applications and trucks.  This is the most common injector  used.  Good for 318hp at 2100 rpm in most applications.

7E series injectors (ie: 7E65) were installed in engines that were in coaches.  These injectors are designed for economy and also to somehow reduce the amount of black smoke (unburnt fuel) when tipping into the throttle.

The are all interchangeable provided you change all of the injectors at the same time.  You do need to set the injector timing, but he recommended 1.460 for all of the three series (65s).  He didn't recommend changing the cam timing when going from a 55 series to a 65 series.  I'm not sure about that bit of advice, though.

Any feedback on the above info?

Mark; if you want a 318hp go with 7E65 injectors the problem for you maybe the rpms the 7E65 use less fuel at the 1800 to 2000 rpm range according to DD  not the 1400 to 1800 range  have a great evening

Mark

Do you have the service manual for for a 8V71. In the tune up section in the back answers some of your questions. Others you will have to read the entire book in detail for. My newest book is 1995 with many pages that were last up dated in about 1984. It is interesting the older manuals 1970, 1960, 1950 & etc actually have a little more detail then the newest ones. The newer ones work a little more on the parts changer thinking. The older ones go into how to overhaul a generator, starter & much more in great detail. They did not send everything out like today. I do not know all of your answers. The GM 4104 671 had E series engines, low block, 2 value heads, and other differences. The N was a later series engine that a specific port liner size, 4 value value head, later style taller block, I think more compression & etc. One  example  from a 1971 book air lnlet port heights of various engines. 71E 2 value-.703, 71E 4 value-.703, 71T 4 value-.900, 71N -1.050 [ I think all of the N's were 4 value]. To vary the power various injectors having different fuel outputs & type of spray tip used. Like stated already the total of different injector variants is almost uncountable.  60 injectors is the max. size for std value train timing. 65 and above require 1 tooth advanced gear timing. Note in book- injector size 60 and below installed in a A timed engine instead of timing per book of 1.460 use 1.484 until you can change gear train timing as soon as possible. This also is states to do the reverse in a std. timed engine with some  65 and larger injectors. Turbo engines are to remain std timed no matter what the cam timing is, the 1970 book that I am looking mostly calls 1.460 for all of these. Different newer year models use different different injector timings. These engines are unlike nothing else as they have so many variations that they could be assembled. It is said the inline 671 has more possible combinations then any engine other engine ever built. Fun stuff like installing 4 engines 2 LH trun and 2 RH turn to one transmission to basically make one engine is one example. Have you looked at the Volume 1 & 2 parts book, looked at the V71 coach engines parts book, there is a field service manual with a lot of good info. May 1984 it states there is a 7E65 injector that has built-in advance cam shaft timing. I think this means you can use it with a std gear train. I would say it would takes years of training, reading & working on these engines to learn a lot of the variables. There are so many different options for stationary power, truck, marine, forklifts, tractors and anything else that needs power ,that I doubt any one person knows it all.
The 8 digit number on the block is broken down by each number in the first pages of the service manual. If you have the build plate on the value cover that will even go farther as to the way that exact engine left the factory. If that is mission the 8 digit and serial number the dealer can give you a print out of it. I think this option is still available.
I am not an expert by any means, I have read all of the book mentioned above and more cover to cover more then once. Each time I am surprised at what I missed last time. Maybe there is to much to absorb with just a few readings of one manaul. Just in general knowing knowing where in the book is enough, makes it easy to look up when needed. I use a yellow hi lighter for the very important in various sections. I am only touching the tip of the iceberg here. You could make a hobby of learning the variables and various options of these engines. They have also updated many parts as they went along as direct replacements. Many of the parts do not show up in the new computer parts computer listing as currently available. The young parts man may tell you they never made that. You could have part in hand and even a old parts manual but occassionall as the number is superced several times it end in a dead end with the DD parts computer on some of our old stuff.Series 53, 71, 92, 149 cubic inches per cylinder. I think I remember the following correctly- number of cylinders for one engine. 1, 2, 3, 4, 6, 6V, 8V, 12V, 12, 16V, 20. The 20 was a 149 cu, inch. per cylinders for some train locomotives not as sucessful a engine as the 16-149. A inline 671 in a bus might have been 175 hp, truck 238hp, turbo truck 275 to 300, marine appliaction 425 to 450hp. We are talking WWII these last 2 engines were in marine landing craft. As I remember they ran these engines at 4,000+ rpm's for a while at full battle speed their life expectency was 45 minutes, one trip to the beach. Later they slowed those engines down to about 3600 and the props stopped cavating, more speed, and longer life. You could install 2 engine via a common transmission. or 4-671's [ 24 cylinders ] to a common trans. each of these engines were complete independent separate engines. 
I Hope this is of some help.

I have a 4106 with an 'A' timed 8V71 and N65 squirts, also a VS2-8 and 5:55 rear end. This coach weighes 25500 ready to go and tows a 4400 lbs. towed.   A home brew propane system handles the hills nicely. This unit gets 9+ per gallon on the flats and 6.7+ in the western US.>>>Dan

CraigC, a very good post about the 2 strokes but outside the USA there was so much more available for those engines like cams different liners, blowers something you will very seldom see here is the 3 rotor blowers makes a lot of air for the engines that run above 10,000 ft.DD kept good records on the engines when we would change blower drives,injectors or anything on the engine it was reported to Detroit but independent shops did not do it ,if you buy parts from a DD dealer for a overhaul today with serial given to them the parts are going to be for the engine of record.Working for a dealer we were never allowed to get out of the box like others some of these guys out of the box could work miracles with the engines.     

The problem we allways had was everybody thought they could do their own repairs on the engine and some could but the 2 stroke is not an easy engine to work on requires a bunch of special tools that most people do not have.Will allways be my favorite engine even though I have 60S in my Eagle now

CraigC, thanks for all the info.  I do have the 4106 manual and the 8V71 tech and parts manuals.  Like you, I have read them cover to cover of the years.  The engine in my 4106 with Spicer has a dead cylinder.  It's either a cracked liner or a burnt valve.  The Previous Owner loved ether.  I stopped and looked at the bus in the middle of summer, before I bought it, the old timer used ether!  It was 70 degrees!  I knew the engine was tired, but she's taken me and my family much further than I ever expected.  The engine has 562,000 miles on the last rebuild.

My manual is from 89, but it does have addendums that are dated later.  Section 1.7.1 has a table stating that N65 white tag injectors use STD cam timing, but N65 brown tag use Advance timing.  I think I understand the differences between C series, N  and 7E series injectors, but I don't know what the differences are between white and brown tag.  I called my diesel pump and injector vendor and still didn't get an answer.

Utah, I'm happy to hear from someone that us running the setup I'm considering.  I'd like to learn about your propane system too. Do you get much smoking under converter lockup and low rpms?

The other side of this is that my engine runs so low on power now, that even if N65s have lower torque than the N60 I have now, it still may be MUCH more after the engine is running on all 8!  I'm also used to downshifting to keep the rpms up and will often shift to third at 55 mph when approaching a hill, just so I can keep the rpms up and ride the governor at 55 all the way up it.  When I'm pulling my trailer (7500 lbs) I need to drive it in this manner all the time.

Thanks for all of the great feedback.

Mark

I looked at a 1980 info. sheet that has several types of 65's  It has different letters and number-letters numbers in front of 65. It does not talk about colors. My guess is a deviation of the above mentioned differences. They have different plunger types, different nozzle tips that have different numbers of holes of different hole diameters, and different angles. The normal fuel delivery for a 65 injector is min of 64 to 69 cc's per stroke at WOT. Even the min. & max. fuel delivery varies with some of the different variants of a 65 injector. The military version, & fuel pincher have different variants in fuel settings that are different then the norm. You need to replace one injector with the exact type you take out. A few years ago I ordered Brown 65's. I got 6-N65's & 2-N65B's they told me the B's had a faster cut off. I wondered if this was true but I needed them and I could not tell a difference in the operation. I am not recommending this, just telling you what I once did, with the injectors rebuilder's recommendation.
I assume you know your injector in the bad hole is good and the cam lobe is OK.
You are looking at a used engine from someone that says it has certain injectors but the 318 hp is just a general term used by  many for a 8V engine. They do not really know what they are selling. Do they really know the history. Are you buying a pig in the poke that is really no better then what you have. Unless you ran a compression check maybe pulled pan and looked at brgs, crank . Was it run on a dyno how do you know what you getting. It could have cracked heads that many not should up until 30 to 50 mile of driving. A & R diesel in Fontana, CA. normally has some complete in frame overhaul kits which might give you a better engine with some know facts about it. If you do the labor or have some one at your shop do the major work and have a DD expert run the racks. If you do this make sure they get the small sheet metal retainers in the wrist pins hole correctly. Just a thought. There is also a section in the book that tells you how to check the Gear timing without completely taking the engine apart. Just thinking out loud.
Sorry, I did not answer your injector question exactly. I do not know the exact difference between the 2 but it is a combination of the above variables I am sure.
Good luck
Craig C.

Onelap, I get NO smoke anytime!! I dont know why but this engine will not smoke. I've  had it to Southern Oregon diesel for the last tune up and all was well, during the trip I climbed a ten percent pass at ten thou alltitude and could just see a small amount from the pipe. ( the propane DOES make a difference and keeps the heat down)>>>Dan

Claim jumper

Just curious, how much cooler does your engine run. How much propane are you injecting. How much are you using in a 100 mile mountain trip or some example. Are you injecting some propane all of the time at different amounts or just when you need extra power with a preset orifice?
Thanks for any input.

Craig

I finally talked with a tech that knows what he was talking about!  He has 30 or so years experience working on two stroke Detriots.  He only works on two strokes now, but mostly in the marine industry.

The color of the tags on the injectors stands for the level of rebuilding that injector went through.  White's had a lower level of rebuilding, Browns had the highest, such as new nozzles instead of just cleaning and reusing the old nozzles.  He only uses N series injectors.  They will work in trucks, coaches and marine applications.  He will use a specific injector for gensets and industrial applications because they normally run at a set rpm and are sensitive to changes.

He said it was okay to install N65 injectors and keep the standard cam timing.  The engine will smoke "slightly" more but won't be a problem.  Since this engine project will be on the floor, it'll take only a few hours to remove the back engine cover and advance the cam time one tooth to set it to A timing. 

I asked about reduced torque with N65s versus N60s injectors.  He express that the N60s would not necessarily have more torque.  He thought that that N65s would likely have more torque and HP all along the torque curve.  He said that the marine engines need huge torque and that, in general, the larger the injector the more torque the engine will produce.

That's the skinny.  I finally got the answers to my questions.  Now let's learn more about this propane system.

Propane "injection" is not accruate, its really propane "mixing" in my case. I mix at and in the intake chamber above the blower and use it for hill climbing only. (or passing a truck) I have a 68 Gallon laydown tank in my rear bay so propane lasts for a long time at this rate. >>>Dan

OneLapper, as I recall, the advanced timing was two teeth, not one tooth. I often wondered why I did not see anyone refer to advancing by one tooth.

Now I have. Are you sure that you want to use this setting?

For what it's worth.

Tom Caffrey

One Lapper
I hate to disagree but there has been some slight misunderstanding between you and the tech.
I disagree about his explanation of a White and brown.
1970 thought 1994 DD literature Says a white N65 should be used with Std cam timing with 1.460 injector timing. Brown N65 is to only be used with advanced cam timing and 1.484 injector timing. C series injectors that I have seen are all light blue-green, N70 black tag, N80 green tag.
Yes your marine mechanic stating N65 in std engine will smoke is correct. The boat engines have been using  large injector for ever. In many parts of the country law enforcement would disagree with his choice for highway use. With a light foot and watching it carefully you could get away with it. You can set up a throttle delay to eliminate the take off black smoke. It will not stop if your foot is too heavy climbing hills, even at lower elevations. There was a time when N70 were legal in a natural 8V71. They would put out a lot of black smoke when lugged a little. The DD book has called for Brown N65 and ADV timing for decades. You did not state if he was referring to your white N65's. There were a lot of old timers that once did a lot of experimenting,  but with smog rules and DD in house of only putting them back together like they came from the factory. It is getting harder all of the time to find the ones that once experimented.  Most of these guys are retired now or gone. We had a friend that was involved in setting DD up to drag race trucks. We have asked him many questions I only wish I could remember more  of what he said, but he is gone now.
Just look at one specific section in a parts book of just one series of a DD engine and look for one specific part and look at how many different choices that are available.
The explanation about torque you gave is not the way it is. It was explained earlier. There is a little confusion there. Bigger injectors more hp and more torque. Std. timed engines will have their torque at a lower rpm with a wider range of rpm's. The range is perfect for a manual shifted 4 speed bus. The adv. timed is a higher narrower rpm range more suited to a transmission with many more gears then a stock bus has. Std timed engines get better mileage. From my personal experience most of the time you can not use those bigger injector's power because you do not have enough gears to shift up one gear because the spread is to wide from the gear you are currently easily climbing a mountain at about 1800 rpm's while you can easily throttle to your governed speed. RJ long talks a lot about backing off the throttle and take it easy.
Advancing the timing is moving only one tooth on one set of gears. If you do so, write all the marks down for all of the gears before you take them apart. Check the book carefully all of the info is there.
I will get off my high horse and go away now.  I am sorry I just did not feel you had the complete answer.

CraigC:

God I wish you were local to me.  I have a 8V71 Natural with 7E65 injectors and a 5 speed manual.  The engine was just rebuilt.  It smokes black under heavy throttle but when feathered clears up.  How should I set it up to clear up the smoke?  Also, after it sits for awhile without running, like a week or so, it smokes white until it warms up.  I know nothing about the cam timing or the supercharger timing.  I would love to not be embarassed when hammer down and also not have to clean the back of the bus of soot after every run.

2 strokingly yours,

ojgetaway32

One way is to reduce to the N60 injectors.  You'll not only get better fuel mileage, but the torque is rated at 1200rpm rather than 1600rpm on the 65's.  I had brown tag 65's standard timed in my bus and got tired of the smoking at high altitudes with lack of power and turbo'd the engine-but that's a bit radical.  You could also turbo your engine a keep the 65's-they commonly called those smoke turbos.  It will increase your power and torque from 300hp and 800lb/ft with the natural 65's to 325hp and 975lb/ft torque.  With the lower hp setting, you don't need an aftercooler and you'd get better mileage to boot-no more smoking at higher altitudes.  Good Luck, TomC

Onelaper, I know the answer on reading some of the injectors  
the tag is for fuel delivery in cubic millimeters  ( white the lowest and brown the highest)
the number 6 years ago was the number of holes in the tip (but I think that is 8 for that injector now)  
5 was the angle of spray  
n was for a 4 valve head

It's the same principal with the 3 number and 1 letter injectors now I may be off base but that was told to me in the 70's (many night sleep since)

Ojgetaway,I helped a friend of mine change his blower to stop the smoke he used a full capacity blower with a 195 gear ratio he did not want to spend the 10 or so grand to upgrade to a turbo worked for him (he had a 80% blower)

I put a new blower when rebuilt, I didn't know I had choice of percentage.  How do you know what you have?

OJgetaway32

Clifford you and Craig are getting close on reading of the injectors I never heard of tags applying to stage of the rebuilding process love reading these type post

These post are fun to me also. My favorite are the mechanical and great bus adventures. I find it amazing how many new things one can learn everyday, now if I could just remember some of it!!!!
What Clifford is saying in different words that there are several gear ratio in the gears at the drive end of the blower. The factory used different one over the years.  1.95 to 1, 2 to 1 , 2.05 to 1 are some numbers I think I remember for blower speeds.

Old get Away - Like Tom C said  a 60 numbered injector probably would have been a better choice. Do you know if your cam timing is Std or Adv. If Adv the DD book says 1.484 inj timing, I cleaned up a smoking engine by going to 1.470 injector height setting. If you have Standard timing then I would try per the book a setting of 1.460. Tom C has a friend in Bakersfield, CA named Don Fairchild that is a whiz kid on these I would talk to him.  Luke in New Jersey is another excellent source. I am sure others on this board can recommend someone close to you.

I am just making a lot of guess from afar.
If your engine only smokes when sitting for days and it is different then just sitting overnight. Plus if the weather is warm enough in both examples for complete combustion at start up. Does your engine start immediately or turn over some before staring as it is injecting fuel that is not burnt--like weak batteries. Another thing if your check value on the main line is leaking, small leak letting air in the system, maybe fuel pump seal or worned shaft. Are you even back at the engine when it starts. Does it fire completely smooth immediately or minor roughness while smoking and then smooths out at the same time it stops smoking.  Are you using oil Detroit's always use some oil if not something is wrong such as a cross over fuel line under the value cover could be sucking air sitting and adding diesel to the oil while running, diluting your oil. Pretty soon no run ever again without big money transfusion. Sorry for poor joke. If you have any doubt on this, a oil sample will show diesel fuel percentage in oil and the current weight of the oil. Example of 3.5% fuel dilution will make a Delco 40wt oil come back at less then a 20 wt oil. Not trying to scare you but so many possibilities. My current bus engine it took forever to find my problem. It was 2 things. one the check value and worn shaft from the fuel pump.
If it runs rough when starting take the return line off after the restricted fitting on the return line this fitting will be stamped in something like this "R80" put this in a bucket hold line against the side. You are looking for any air bubbles or fuel that almost looks like foam during the start up and if the bubbles clear up about the same time the engine smooths out.
If you have a DD Service Manual look in #2 Fuel Section, Section 2.0 troubleshooting it will tell you a lot about what I mentioned above and much more.
Clifford
this info came from a May 1994 book same section as above. pg.8
I was thinking the same thing as you about the N65 brown & white having different min to max. fuel outputs, but they both have same settings of 64 to 69. This page shows that you are correct that not all 65 injectors have the exact same fuel output it list several 65'. Last night I was looking in a inline 671 book of about 1972 vintage and it listed more injectors. Higher output M's, NH65-70 to 72, lower 7E65 63 to 68, it seem 64 to 69 is the most common for N, C, B in the 1994 book and more in other books. 1994 book pg 10 talks about 3 different types of plungers. "The fuel output and the operating characteristics of an injector are to a great extent determined by the type of plunger used"  "The lower helix angle retards or advance the end of the injection period" Do not mix these plungers in overhaul of an injector or spray tips. "erratic operation will results and may caue serious damage to the engine or equipment it powers"
Page 20 "The injector  fuel output is largely dependent upon the combined output of its plunger/bushing and spray tip assemblies.
About 2000 I had some new Green N80's I looked at part numbers and as I remember to change it over to N70'  it would only take a plunger. DD told me that no injector parts were in their system anymore. I have someplace a double sided chart that list several injectors and the various DD part numbers it was interesting to see what the differences were between the different injectors. Did it tell me the exact answer we are looking for in black and white, I would say no. Page 12 talks about spray tips with specific numbers stamped on them what their flows rates are. examples 6-.006  flow is 22, 7-.007 rate 69, 8-.0055 rate 26, 8-.006 rate, 9-.0055 rate 48, 9-.0058 rate is 69. As I remember the first number is the numbers of holes & second is diameter of each hole. I will look for the the above chart, scan it and e mail the chart to anyone that can post it if anyone is interested. 

Quote from: pvcces on September 18, 2008, 10:17:26 PM
OneLapper, as I recall, the advanced timing was two teeth, not one tooth. I often wondered why I did not see anyone refer to advancing by one tooth.

Now I have. Are you sure that you want to use this setting?

For what it's worth.

Tom Caffrey

Ugh.  I'll get in touch with the tech I talked to and ask about the number of teeth to advance the timing.  I thought I read it in the tech manual.  I may have gotten it completely wrong which is a distinct possibility.  I never counted the actual teeth, but it's difficult to make heads and tails of the pictures.

I love the feedback.  Keep the info and questions coming!

Mark

onelapper, if the engine is a late model 71 most have the marks from R to A on the gears like a 92 series   good luck

The engine block is a replacement block according to the serial number stamped on it.  It comes up as a 1981.  When did they stop making these engines?  I plan on removing the back cover to check over the cam timing so I hope to find timing marks on the gears.

Can anyone lead in the right direction to find a chart of hp & torque ratings for an 8V71?  I'd like to see how much difference there is between N60 std timing and N65 advance timing.

Another thing:  How many of you guys are running without mufflers?  I passed a purple 4106 with "straight pipes" on the highway some time ago and it sounded GREAT!  Might too loud inside, though.  I have a 4" inlet/outlet muffler that doesn't seem to flow enough.  It's popped of three times.  Each time I felt a surge of power, then heard the noise!

Quote from: OneLapper on September 20, 2008, 08:31:08 AM
The engine block is a replacement block according to the serial number stamped on it.  It comes up as a 1981.  When did they stop making these engines?  I plan on removing the back cover to check over the cam timing so I hope to find timing marks on the gears.

Can anyone lead in the right direction to find a chart of hp & torque ratings for an 8V71?  I'd like to see how much difference there is between N60 std timing and N65 advance timing.

Another thing:  How many of you guys are running without mufflers?  I passed a purple 4106 with "straight pipes" on the highway some time ago and it sounded GREAT!  Might too loud inside, though.  I have a 4" inlet/outlet muffler that doesn't seem to flow enough.  It's popped of three times.  Each time I felt a surge of power, then heard the noise!

Actually they still make them! But not for the general public! Big industry and military are the only ones with access to NEW ones!

4" inlet? hmmm sounds small to me! Shoot my pick up truck has 4" from the Doug Thorley headers back!

And if you run the pipes to where they stick out past the back of the bus you should only hear a pleasant (at least to me it is!) vmmmmm inside! FWIW
;D  BK  ;D

MTU builds the engines for military (NATO) 520 hp the DDEC 8v71 went out of production for civilian use in 2001   have a great day

Mark, www.powerlinecomponents.com   check literature for the rating of different engines   good luck

I have black N70 injectors on mine and do not like them, a gift from the PO. I spend too much time looking in the rear view mirror trying to keep the smoke down. My fuel mileage is also not what I would like. One would think that there could be a way to adjust the stroke or rack travel so it would deliver the equivalent of a smaller injector. Why is that not possible?

Barn Owl.  I would wonder if you have the correct injector and cam timing.  But, from everything that I've learned in the last couple of weeks while trying to find the answers to my injector questions, it seems like N70 injectors would be used on Turbo engines only.  Do you still talk with the PO?  Might be a question for him.

Mark

Laryn
I think it would be best to change injectors. I am not recommending any of the following. You asked  I have seem the following in the book only. May 1977 DD book Section 14.14 , pg 1 Supplementary Governing Device Adjustment---Engine Load Limit Device. Pg 2 Power Control Device.
Another thing I noticed is to adjust the high speed this requires a different spring for the lowest settings. See the "The Governor Settings for TT engines. This in the 1994 book inline 671 they reduce the power up to 83%. I am guessing that might help some. Sec. 14.3.5 pg. 1 & 2.
Both of these the book is calling the engines to be tested on a Dyno.
If you talk to a DD whiz, I know some have experimented with injector height settings. I once had a inline 671 that smoked a little under a constant hard load. The book called for 1.484, I was told to set it to 1.470 and it cleaned it up. This is not close to amount of smoke that a N70 is capable of putting out.
Do you know if you have Adv. timing? If you had N65's with std timing they say use 1.460 for inj. height instead of the normal 1.484. I have not seen any thing that talks about this for N70's if you have Std timing.
You asked for unusual thoughts for your N70's.  About 8 or 9 yrs. ago someone posted about Colonial Diesel in I think in Mass. I dealt with them, excellent price and advise. I looked for teir number about 4 years ago, it has been misplaced. Their price was about 1/3 of my local price high injector shop.
I would hope you have ADV timing. I wonder if you can recycle unburned diesel back to the tank!!! Just kidding.


Mark
Sorry to pick on you again.  All of the following info. is for  Non Turbo 71 certified automotive engines. Each year various recommendations changed. With Adv. cam timing. This info is from various manuals books between 1967 to 1994
1978 was the last year for C70 injectors.
1972 was the last year for N70 injectors. 1973 and 1972 inj. ht. is 1.484 and 1970 and 1971 inj. ht. is 1.460
You will find this try of info. in the Tune up section usually next to the last section in the book. Sec. 14
The N70 were not even in the tune up section for the turbo engines. Before smog rules came along.
 

CraigC, I don't feel picked on so don't worry about that!  I'm interested in the N65 injectors, Advancing the cam timing and maybe playing with the injector timing a little bit.  I'll let you know how things progress.  I still have to compression test things, look at mains and conrod bearings, look at the blower situation (heavy scores in the lobes), etc.  Tons to do.

Mark you do know that a 2 strokes has to be running at 600 rpm to do a compression test that's the DD way

CraigC,

Update:
I tried to contact the PO but no response yet.  He didn't seem to know much anyways when I first bought the bus because he said too many years had passed. I do know that he had a local marine shop do most of his service and one time had an engine swap done. I can only hope it is advanced timed.  I have spoken to an old Trailways mechanic (Ricky Hall) who lives south of me and he said he would be willing to do a tune up. He is in his eighties and still tinkers with detroits on occasion. I told him about my miserable fuel mileage and he said he thought it was about right and that most exaggerate what they get. I am not so sure about that because my Father's bus gets better than mine and he has more hp. I am wondering if I might have some dribbling injectors.  I would love to change them but there is just no way I can justify it. I am lucky if the bus goes out three times a year on what are relatively short trips. I just have too many mouths to feed at this stage in my life. One step at a time I suppose. I will continue trying to contact the PO. Thanks for your input.

Laryn

Quote from: makemineatwostroke on September 24, 2008, 07:19:15 PM
Mark you do know that a 2 strokes has to be running at 600 rpm to do a compression test that's the DD way

Uh, I did not know that.  I learn something new.  Well, I'll have to figure out if I'm rigging up the engine to run while it's on the pallet or cheat and just crank it over to check the delta between the cylinders.

Starting the engine isn't the hard part, it's rigging up some type of radiator.  Maybe just a hose forcing water through the engine, or long hoses going to a 55 gallon drum filled with water?