Injection pump timing

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

Moderators:plenzen, Nissan_Ranger

Post Reply
oak4000
Posts:13
Joined:14 years ago
Location:eugene, or
Injection pump timing

#1

Post by oak4000 » 14 years ago

i my be thick or just not understanding (wouldn't be the first time according to my wife) i am wanting to adjust my injection pump timing to advance it a little to help with my cold start rough idling, i went out spent a little time trying to understand how to do it and just spun my wheel around and around, any feed back would be great

EvergreenSD
Posts:70
Joined:14 years ago
Location:Eugene, OR

#2

Post by EvergreenSD » 14 years ago

First you need to loosen the four nuts that hold the pump onto the timing cover. Two of these are hard to reach (or even see very well) as they are between the pump and the engine block. Once these are loosened a bit you should be able to move the pump with respect to the engine block. It took me a little bit to figure it out too. It does not move very much and a little does alot. Turn it counterclockwise to advance it. That's all there is too it.
'82 SD22 720 Kingcab with flatbed

zen
Posts:118
Joined:14 years ago
Location:london uk

#3

Post by zen » 14 years ago

Make sure you mark where it is before moving!!! You only need to move it about a pencil line width if that..
turbo it

(sd33t home turbo set up if anyone is interested..)

User avatar
philip
Posts:1494
Joined:15 years ago
Location:Southern California, USA

Re: injection pump timing

#4

Post by philip » 14 years ago

(This post is a consolidation from another thread on the same subject)
fud2468 wrote:I have a Popular Mechanics Imported Car Repair manual 1975-83 that says 20 degrees BTDC for the SD-22. It gives no information for the LD-28 or other import diesels.
Ray Mac
TheDieseliminator wrote:The LD28 has an exact initial injection timing of 7° and is far different in the case of an SD22 (since its injection timing is 20° and 18° for California models). I found the above specification right on the back cover of my 81 diesel FSM.
There is a bit of variance in base timing specs for the SD fours. There are three different injection pumps possible(Inline RBD-MZ, VE rotary, & C.A.V.-DPA), four pumps when you include an all mechanical marine version of the inline pump).

Image

Image RBD-MZ inline.

Image


This diagram illustrates the sequence of events through the combustion cycle in a diesel engine.

Image

True injection timing (not ignition) begins the moment fuel begins to be discharged from the injector nozzel (which is later than the moment of spill port closure in the injection pump). The moment of discharge will be affected by injector pop-off pressure (typically 1,600 psi in SDxx engines), leakage between the pump plunger and its barrel, and any air present in the delivery line. For example, if the injector pop-off pressure is significantly lower than 1,600 psi, fuel injection will begin earlier (further from TDC). Conversely, when the injector pop-off pressure is significantly higher, then fuel injection will begin later (closer to TDC). Air in the line will have a retarding effect because you are compressing that trapped air until the injector pops off.

Here are some clues that your timing is not optimized for the fuel you are using (assuming normal engine temperature):

1) Late timing: lowered power, increased fuel consumption, elevated coolant temperatures, black exhaust visible under load, lower NOx, possibly increased difficulty starting cold.

2) Early timing: lowered power (subjective), perceptable rpm instability at cruise, combustion clatter (transcient metalic knocking) at lower rpm more prevalent with cold engine, elevated oil consumption, higher NOx, piston crown damage.


The factory shop manual and diesel suppliment outline a process for setting the injection pump timing.

Injection Pump Timing How-To For Nissan SD22

Before beginning set parking brake, chock wheels, disconnect battery ground cable.

1. Thoroughly clean around high pressure injection lines, and delivery valve holder for cylinder #1

2. Remove the band clamp securing all four injection lines together.

3. Remove injection line from cylinder #1

4. Remove the wedge shaped lock plate from the delivery valve holder for cylinder #1

5. Remove the Delivery Valve holder, delivery stopper (if so equipped), & delivery spring. Replace the DV holder and lightly torque.

6. Install a drip spout on Delivery Valve holder (will direct exiting fuel into a catch cup).

7. Turn engine in normal rotational direction to about 30 degrees BTDC compression stroke for cylinder 1.

8. Pump the hand primer while very slowly rotating the engine toward TDC (clockwise). Fuel will drain from drip spout. When fuel just stops dripping, or slows to 1-2 drips every 5-10 seconds while operating the hand primer, stop turning the engine.

9. Locate timing pointer on the cam gear cover and the chisel mark on the rear most edge of the crankshaft pulley. Setting is 18-20 degrees BTDC. Adjust by loosening pump mounting nuts, rotating the pump housing if/as needed, tighten, and recheck. As viewed from the front of the truck, rotating the pump housing counter clockwise will advance the timing. Check 2-3 times after final adjustment, if done properly the same result will be observed each time.

10. Remove drip spout, and DV holder. Carefully reinstall delivery spring and stopper (if so equpped) being very careful to ensure no dirt or debris enters the pump. Torque the DV holder to 22 ft. lbs., then loosen, then to the final torque of 25 ft. lbs. install the locking clamp, and tighten securely.

11. Reinstall the high pressure line, and tighten. Install band clamp. Reconnect battery cable, start engine and check for leaks.

12. Congratulations you have just successfully checked or set the timing on your SD22!!
Last edited by philip 14 years ago, edited 2 times in total.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

oak4000
Posts:13
Joined:14 years ago
Location:eugene, or

#5

Post by oak4000 » 14 years ago

Thanks for telling me to only move it a pencil lead, was figuring it was much like timing on a gas engine where you can move alot.

What is the purpose of the two lines at the back of the injection pump that run over to the throttle body and intake neck?

I don't have the altitude adjustor, is it connected to that?
thanks

User avatar
philip
Posts:1494
Joined:15 years ago
Location:Southern California, USA

#6

Post by philip » 14 years ago

The rear most hose is venturi vacuum signal from the throttle body that is used to move the fuel rack against a spring loaded diaphragm depending on engine load.

The more forward hose is atmosphere vent.

There are no connections to the altitude compensator. See COMPENSATOR
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
Knucklehead
Posts:148
Joined:14 years ago
Location:Phoenix

#7

Post by Knucklehead » 14 years ago

Think of those vacuum lines as your throttle cable.
'82 standard cab 3 axle SD22 turbo
'89 int'l 9700 Cummins 444 (855 ci)
'29 HD FD export model

oak4000
Posts:13
Joined:14 years ago
Location:eugene, or

#8

Post by oak4000 » 14 years ago

Ok one last question Ithink i have on this. Is it normal for my pump to only to be able to move maybe a 1/2"? I loosened the four bolt i could only pull the pump just a little counterclockwise and then tighten it down while doing so. It was late and the last thing i was doing so maybe got a little impatient, not sure if it was adjusting the pump or changing the fuel filter, or both made the cold start better but need a little more tweaking. Let me know if it is normal for only able to move the pump a small amount or did i miss a bolt or need to remove the from cover on the gears or something, thanks a bunch for the advise.
82 sd22, n/a for the time, 5 speed, 250k, standard cab, 2wd

User avatar
philip
Posts:1494
Joined:15 years ago
Location:Southern California, USA

#9

Post by philip » 14 years ago

oak4000 wrote:ok one last question i think i have on this, is it normal for my pump to only to be able to move maybe a 1/2" i loosened the four bolt i could only pull the pump just a little counterclockwise -SNIP
SCROLL BACK UP this thread to the diagram of the reference marks on the injection pump (alignment). There is no reason to deviate more than an 1/8" +/- of perfect algnment of those marks. You must use the drip method outlined in detail in the FSM to verify and set timing. Don't fool yourself into believing you can set timing by "seat of the pants" performance or how it starts

Stop and think about WHAT is resisting pump body rotation after you loosen the nuts.

CLUE: There's four of them.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts:5351
Joined:15 years ago
Location:Duvall, Wash.
Contact:

#10

Post by asavage » 14 years ago

CLUE: There's four of them.
AHAHAHAHAHA!
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

billyg
Posts:16
Joined:14 years ago
Location:Athens Al

Injection pump timing

#11

Post by billyg » 13 years ago

Phillip was dead on in his Post dated Sun Nov 12, 2006 8:08 am above, I TRIED setting it by the seat of my pants and didn't accomplish anything. I had verified the valve clearances 3 times and just couldn't figure out why it still sounded like they were out of adjustment so after reading this thread, I went out and loosened the 4 nuts on the pump and tried it by 'listening'.......no difference, AND it sounded absolutely awful on startup just like some here have described. Even after it was warm, under acceleration about 1500 rpms they would knock. being the persistent guy that I am and having the 82-83 FSM which included both the gas and diesel versions of the truck, I borrowed a buddy's 81 DIESEL (only) truck FSM.

Lo and behold, the section on 'checking and adjusting injection pump timing' actually had the procedure Phil gave above, where you 'adjust' the timing. My FSM only had the 'checking' part, no instructions for 'adjusting'. When I followed that procedure, I wound up with my timing mark being between and 1/16th and an 1/8th of an inch COUNTER clockwise from the factory mark (looking from the front of the truck). Ran like a new vehicle, started after 1 glow cycle on a 30 degree morning with no appreciable smoke with an 'only perceptible to me' knock that will probably be cured by moving the pump CCW another 1/64 of an inch. It's a judgment call as to when the fuel actually stops (NO perceptible movement of the fuel in the Tygon tubing?) in Phil's procedure and i probably stopped a little shy of where it should have been (if you try it you'll see what I mean) , but ALL of the starting issues went away.

The next unknown is how in the world could the timing have gotten that badly out of whack? I've got my story posted in the user's rigs of this forum if anyone would like to comment. It did sit for 8 years without running but I still don't understand.............on to the next 'issue', a vibration that sounds like a u-joint on decel but isn't.

this forum is wonderful..............
"Let me control a nations currency and I care not who makes the laws" N.M Rothschild

User avatar
philip
Posts:1494
Joined:15 years ago
Location:Southern California, USA

Re: Injection pump timing

#12

Post by philip » 13 years ago

billyg wrote:SNIP-
When I followed that procedure, I wound up with my timing mark being between and 1/16th and an 1/8th of an inch COUNTER clockwise from the factory mark (looking from the front of the truck). -SNIP-
The next unknown is how in the world could the timing have gotten that badly out of whack? -SNIP-

this forum is wonderful..............
It took me awhile to find there's a small (but significant) wobbly clearance between the injection pump and the cam cover plate when you reposition the timing. I learned to remove (free) all four injection nozzle lines and then ... loosen the IP four nuts just enough to rotate and back to get the timing right. And after tightening down those 4 nuts, rotate the crankshaft two rounds and REcheck your timing before reinstalling the four fuel lines.

Timing on this engine is an art as much as it is a science. :wink:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts:5351
Joined:15 years ago
Location:Duvall, Wash.
Contact:

#13

Post by asavage » 13 years ago

You just want to style yourself an artist in your dotage! Hah! Stick to the wrenches!

User avatar
philip
Posts:1494
Joined:15 years ago
Location:Southern California, USA

#14

Post by philip » 13 years ago

asavage wrote:You just want to style yourself an artist in your dotage! Hah! Stick to the wrenches!
Your first playful Christmas ad hominem. Thank you. :wink:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts:5351
Joined:15 years ago
Location:Duvall, Wash.
Contact:

#15

Post by asavage » 13 years ago

Trying to get into the Holiday spirit, you know. The Wal-Mart/Costco decorations aren't doing it for me.

Post Reply

Who is online

Users browsing this forum: No registered users and 5 guests