My timing retarded

chris142

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Its been about 4 years and 50k miles since I set it @ 8btdc. Checked it today and it was @4btdc.

I tried to adjust it and I am out of room to move the pump. All I can get out of it is 7btdc.

It's definatly more responsive than it was. Guess I will need an injection pump next time.
 

chris142

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We went on a 7hr trip 1 way. Getting 14mph @75 mph! Remember that I do not have overdrive.
 

icanfixall

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It does sound like the advance is wearing down. How many total miles are on this particular injection pump? I read the 50,000 miles you have driven since timing it but the total miles tells much more. If the pump has reached the limit of timing travel you might be able to move the pump easier is you just loosen the easy to reach hard lines on the back of the pump. If the pump is all the way over it will have the appearance of being turned towards the passenger side fender and look really turned over.
 

Macrobb

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So, two things here:
One, you have to loosen /all/ the IP lines to get it to move beyond a certain range. Also, when you get it to one extreme or the other(pump cocked driver or passenger), the lines won't fit into their vibration dampeners easily, so it's a bunch of tweaking and adjusting to make it work.
Two, if needed, you can skip the IP gear a tooth advanced. Then, your "baseline" is more advanced, and you can "retard" the pump in it's adjustment to make the timing come in again.
Skipping a tooth is done by pulling the front cover off the IP gear housing(exposing the 3 bolts and IP gear), marking where the stud is on the housing, loosening the 4 bolts holding the gear housing to the engine and levering it up just a bit. You want to lever it up until you can get in there and rotate the gear one tooth advanced, using the mark you made for a reference. Then, re-tighten the 4 bolts and fire it up. Check timing, repeat if needed.
Remember - you want to rotate the gear in the opposite direction of the IP - to advance the IP, you rotate the IP counter-clockwise(top towards the passenger side), and the gear clockwise(top of the gear towards the driver's side)

Now, make all your adjustments - get the pump timing right where you want it.

Once everything is good, mark where your IP is relative to the housing, and then /remove/ the IP.
Clean around the IP gear housing cover all the way around it with acetone or something, and apply a bead of RTV where it meets the engine and front cover - remember, we've broken the RTV seal under that cover by levering it up.
The new bead should prevent leaks, with any luck.

Once you are done, reinstall the IP, get everything to it's marks, reinstall lines etc, test and adjust for any minor adjustment needed.
 

chris142

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It does sound like the advance is wearing down. How many total miles are on this particular injection pump? I read the 50,000 miles you have driven since timing it but the total miles tells much more. If the pump has reached the limit of timing travel you might be able to move the pump easier is you just loosen the easy to reach hard lines on the back of the pump. If the pump is all the way over it will have the appearance of being turned towards the passenger side fender and look really turned over.
Its a rebuilt pump from a stanadyne shop in alaska. It looked fresh whem I bought the truck back in 12. No idea how many miles ard on it but I dont think much more than the 50k I put on it.
 

icanfixall

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At 50,000 miles plus a little more a quality rebuilt pump should have more miles in it. Sadly not knowing who in Alaska did the work your kind of guessing. Maybe time for a newly rebuilt or maybe a set of injectors?? When injector springs weaken the timing generally will advance because the pulse of fuel going into the precups happens sooner because of the weak spring pop pressure.
 

Clb

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Ala @IdIot, don't be retarded...
One tooth will wreak havok.
Standyne pump is fine at 50 k, 100k not so much.
+1 on all the above feedback, and loosening all the inj. Lines you can then adjust it.

Btw... I'd love to see 14 average mpg.
 

Macrobb

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Ala @IdIot, don't be retarded...
One tooth will wreak havok.
No, it won't.
The IP gear has 106 teeth. It rotates one time for every two crank rotations(720 degrees).
Therefor, 720/106 = 6.79 degrees of crank timing per tooth.
AKA, for every tooth you advance on the IP gear, you will get 6.79 degrees of timing advance.
On a slightly retarded engine(with the pump already adjusted towards the advanced side), this will put you in the slightly advanced range, which can then be 'dialed back' by rotating the pump back retarded again.
~7 degrees is well within the compensation range of the IP adjustment.

Personally, I've done this successfully on multiple trucks with worn IPs. It keeps them going down the road, getting decent gas mileage and power.



Btw... I'd love to see 14 average mpg.
My last fillup averaged 15.3MPG over 130 miles, and that's a bit low mpg wise - that included 50 highway(70-75MPH) plus a number of 10-miles-from-cold-start(mixed) trips to work and back.
All-highway mileage should be a bit better.
 

Clb

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There IS ALLWAYS 1.
I am not claiming to be right, nor accepting the statement the ip can comp 7 deg's of timing.
WE also had a member swear he could and would build 400 hp dd idi that got great mpg's.
About 10 years back...
Still crickets.
No dought it is possible to ***** the timing and have it run good.
I have seen it, but the timing was way off, it ran like a ***** ape, but,
Why not do it right the first time.
Enjoy your evening.
 

Macrobb

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There IS ALLWAYS 1.
I am not claiming to be right, nor accepting the statement the ip can comp 7 deg's of timing.
WE also had a member swear he could and would build 400 hp dd idi that got great mpg's.
About 10 years back...
Still crickets.
Actually, I believe that being possible. I've seen Justin build a 450HP IDI(and rode in it, no less!), and the thing about a turbo IDI is that it's still the same motor underneath it all(unless you are messing with compression). Of course, you need better connecting rods to handle that 450HP reliably...

So, there's no reason to think that DDing such an engine *wouldn't* produce the same mileage as a mildly turbo'd IDI, because it's doing the same work, and thus requiring the same fuel - the turbo, when not spooled up, isn't adding more air either.



No dought it is possible to ***** the timing and have it run good.
I have seen it, but the timing was way off, it ran like a ***** ape, but,
Why not do it right the first time.
It has more to do with getting the /right/ fuel timing out of a worn out pump. Yes, you can just throw it away and put a brand new one in there, but as the timing bits wear before the rest of the IP, it's entirely possible to 'work around' the retarded timing and keep using the old pump for another 20K or something.
Enough time to save up for a new, high quality IP.

Also, remember that timing isn't just a number. On a DB2 pump, it's a 4D graph, with throttle position, RPM, load, and advance being the four axes.
Factors that affect your timing /curve/ include:
1. Inlet IP pressure.
2. Transfer pressure inside the pump
3. Throttle position, as it pushes against the light load cam(and adjusting the light load cam position will affect this)
4. Spring pressure in the light load advance
5. Spring pressure inside the advance piston
6. Advance piston bore wear
7. Fuel cetane number
8. Injector pop pressure.

With all of these factors affecting your timing, and not in a linear fashion either... it's entirely possible to end up with a setup which is way off at the testing spot(2,000 RPM, unloaded), but perfectly timed under load, resulting in a good-running vehicle.

Or, conversely, it's easy to have it timed 'right', but still off once you put a load on it due to how all these factors affect it.
 

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