8V71 with 7E55 injector

[Utahclaimjumper]

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

[makemineatwostroke]

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

[OneLapper]

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.

[CraigC]

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.

[Utahclaimjumper]

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

[CraigC]

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

[OneLapper]

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.

[Utahclaimjumper]

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

[pvcces]

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

[CraigC]

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.

[ojgetaway32]

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

[TomC]

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

[luvrbus]

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)

[ojgetaway32]

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

OJgetaway32

[makemineatwostroke]

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