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Injector line size. When do we need bigger lines?


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I just did a  bunch of pump work to a roosamaster 370 on my 1206.  It maxes out at about 250 cc's of fuel.  I have a series larger injector on the tractor.  Are the stock lines still big enough? When do we need larger line??  Thoughts?

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The internal size of the injection lines have to match the retraction size of the delivery valve for clean cut off of injection yet keep lines full for next delivery.   Nozzle tips,  hole size in lines and retraction valve size are supposed to match.  Probably not all that important in a pull tractor but for long life of a working tractor , smooth running and low dribble and least cavitation in line very important. 

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When I build a .450 pump, which exceeds 400cc of fuel, then we order up a set of .093" ID lines. Many of these older tractors used .074, or so, but some did only have .062". At 250cc, the .062 will be close to being too small, considering the original spec on those was less then 100cc. The 361 seems to have had larger ID lines than the 407, at least the 1456 I think had the smallest, at .062", trying to cut down on smoke. 

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4 hours ago, Injpumped said:

When I build a .450 pump, which exceeds 400cc of fuel, then we order up a set of .093" ID lines. Many of these older tractors used .074, or so, but some did only have .062". At 250cc, the .062 will be close to being too small, considering the original spec on those was less then 100cc. The 361 seems to have had larger ID lines than the 407, at least the 1456 I think had the smallest, at .062", trying to cut down on smoke. 

They used to say injector lines should be equal length. I don’t think newer engines followed this but the old MDs Wd9 had coils in the line to equalize length. What’s the answer on this.

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9 minutes ago, international560 said:

New engines still follow this, unless they are common rail injection and then the line length doesn't matter as much because they are electronically actuated.

On a mechanical diesel injection system, all injector lines must be the same length, otherwise timing will be off on individual cylinders. 

5.7 , 6.2 , 6.5 , 6.9 7.3 Automotive with a Roosa pump didn’t use equal length. Most others did but not all

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I just looked up old service bulletin.  The 1256 injection pipes were changed from .082 down to .062. (same size as non turbo engines) at DT407 #6663 along with the delivery valve (retraction valve in end of rotor) being lowered from 35c mm to 20c mm displacement to reduce cavitation and nozzle contamination.   All 1206s had the .082 line.    Reason I added delivery valve is in end of rotor as I see some on here and other forums call the metering valve that is governor controlled as being a delivery  valve which of course it is not. 

There was also changes made in the injection nozzle tips at different time.  Some are interchangable and others are not. It get confusing and not unusual to that parts get mixed up over the years.  A person would have to go through all those bulletins along with all the superceded parts since then to make sure of correct parts being used.   

The online parts catalogs are really poor with a lot of that as they don't include serial numbers when parts were changed all the time. 

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1 hour ago, dale560 said:

5.7 , 6.2 , 6.5 , 6.9 7.3 Automotive with a Roosa pump didn’t use equal length. Most others did but not all

Are you sure that the lines were not all the same length on the 6.9L/7.3L IDI engines? I have worked on plenty of these and am pretty certain that they are. I haven't worked on the GM diesels that often to comment on those, but I couldn't imagine that they aren't also all the same length lines. 

 

The pictures below are 6.9/7.3 lines and they all appear to be the same length and I would almost guarantee that they are. 

photo935.jpg

injection_lines.jpg

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Just now, international560 said:

Are you sure that the lines were not all the same length on the 6.9L/7.3L IDI engines? I have worked on plenty of these and am pretty certain that they are. I haven't worked on the GM diesels that often to comment on those, but I couldn't imagine that they aren't also all the same length lines. 

 

The pictures below are 6.9/7.3 lines and they all appear to be the same length and I would also guarantee that they are. 

photo935.jpg

injection_lines.jpg

I always thought the 6.9 had some short ones. The 5.7 6.2 have some that are shorter or appear the be a lot shorter. Maybe if you bend them open So they are straight  they are all same length.

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2 hours ago, dale560 said:

5.7 , 6.2 , 6.5 , 6.9 7.3 Automotive with a Roosa pump didn’t use equal length. Most others did but not all

ooh yes they did,  that is why they are routed or coils in them. years ago I went the GM. upgrading on these diesels years ago and they even specified that lines must be the same length and hold the same fuel.

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A pump and line system should have nearly identical length lines. A common rail system does not need equal length since the injector is electronically actuated as mentioned above. It seems to me early 4020's did have differing length lines. Other than those I cannot think of anything with unequal line lengths.

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25 minutes ago, Injpumped said:

A pump and line system should have nearly identical length lines. A common rail system does not need equal length since the injector is electronically actuated as mentioned above. It seems to me early 4020's did have differing length lines. Other than those I cannot think of anything with unequal line lengths.

That’s what I thought to. I will check for sure, I swear 5.7 or 6..2 have shorter lines.

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some may seem shorter, but they are the same length, they are routed and bent that way to kill excess length on close cylinders. 

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On 2/12/2020 at 7:30 AM, England806 said:

Oversize injector lines will retard timing slightly as fuel is compressible.

No, liquids are not compressible. 

It has to do with volume, not compressibility. 

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Some interesting stuff to learn under the search “compressibility of diesel fuel”.  Rather interesting that the presence of biodiesel in diesel fuel will cause a small amount of injection timing advance because of how the pulse signal travels through the fuel in the injector line.  

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6 hours ago, Gearclash said:

Some interesting stuff to learn under the search “compressibility of diesel fuel”.  Rather interesting that the presence of biodiesel in diesel fuel will cause a small amount of injection timing advance because of how the pulse signal travels through the fuel in the injector line.  

If you google it .this has been discussed here before or online someone had a formula for how much fuel compressed in a line because of microscopic air intrusion. Think it was on a tractor pull website. The answer was it was better to make lines different lengths than to have bends in each one causing parasitic friction and loss of flow volume.  

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