Cummins Diesel Forum banner

Timing of gear for injection pump

24K views 28 replies 6 participants last post by  12valveRussian 
#1 ·
I have the gear housing cover off for the KDP and I know exactly how the gear for the IP fits back on. I have read several posts saying that I can move the gear forward by one tooth to advance timing by a couple of degrees. After reading up on this I realized that many of the gears have certain letters (E, O, C etc). The gears number (serial or something similar) is YSPZIA3. On the outside (next to the teeth), I have the number 3929031 and the letters YSZK G.G. R03 and JQ all intermittently spaced.

From what I've heard on the forums, this confuses me. I know exactly where I should align to keep it how it was but I'm just bothered that none of the letters/numbers makes sense to me. And, which direction to I move it one tooth to advance timing?
 
#2 ·
The gear is not keyed to the shaft. the timing is adjusted by moving the gear on the shaft, not by skipping teeth on the gears.

the marks on the gears are there as a reference when installing the cam and inj pump gear in this application (some do use keyed gears)
 
#3 ·
This much I understand. I will have the cam out tomorrow to put the new gear case on (hopefully tomorrow). I am thinking that I can reinstall the IP gear and as I put the cam and gear back in I can turn the IP gear to adjust timing to the cam gear. In my mind this makes sense, but I may just be way...way off. ...if so, I apologize.
 
#4 ·
turning the gear achieves nothing

Its the pump shafts alignment in relation to the gear that changes the timing. Because the gear isnt keyed to the shaft, You could spin the gear around 180* and throw it on and you still didnt change anything LOL
 
#5 ·
Like I mentioned, I understand that the shaft of the IP has to move to adjust timing.

As I had posted a few posts up I will have the gear on the IP and have the cam/gear out. So when I cam about to put the cam back in I will align the cam gear to the crank gear and then turn the IP gear (with the shaft attached) to align with the cam gear.

Not sarcasm but does that not makes sense? I appreciate any input, at least people are responding. Much appreciative.
 
#6 ·
missed that part...

Yes that will work, but its completely the wrong way to do it LOL

You would have to figure out the actual advance per tooth though. its probably going to end up being WAYYY too much advance with just 1 tooth
 
#7 ·
The numbers and letters on the gears is what confuses me. I don't know if it's the factory setup or not. However, say it is in the stock position (which is approx. 12.5 degrees) advancing one tooth (once again is this just what I have heard so please don't judge me too hard) would bring the timing to approx. 15.5 - 16 degress.

I know it wasn't the 94-98 forum but this kind of what I was referring to http://www.cumminsforum.com/forum/89-93-powertrain/76624-timing-marks-pump-drive-gear.html
 
#8 ·
In theory you could turn the shaft but a measurement of one gear tooth is a giant SWAG. Increasing timing by 3 degrees is only about a half inch movement of the damper. You will be fighting a losing battle trying to reinstall the gear and tightening the nut enough that it won't slip without it meshed to the cam gear. When you pop the gear off the shaft jumps a tiny bit and you have to start all over again. Better to time it right using a gauge or spill port method. Do not rely on the cam timing pin to find TDC either. Some are way off.
 
  • Like
Reactions: 12valveRussian
#9 ·
after all the work I put that would be very depressing...oh well. So what should I do? Pop the gear on and align it to where it was, put the case cover on, and reassemble the truck hoping it all works out or go ahead and try to do the timing?

I really appreciate you have solid opinions. All the searches I have done have yielded me nothing but confusion and uncertainty.
 
#10 ·
The odds of getting the timing set without a measuring device of some type are pretty slim. You could get lucky using the cam timing pin and the IP pin and end up with stock timing. Problem is, IIRC, you replaced the gear case. The cam timing pin is installed in a mount that is adjustable. Do you think it is in the right place?
 
#11 ·
when I pulled the gear off (IMHO slowly and surely) I could swear it didn't move. This is just way out of my comfort zone. I'm so glad that I did the work myself and got to learn a few thing (buying some tools I've been wanting doesn't hurt). I just don't trust anything that I can't swear upon. New gear case comes in tomorrow or the day after. I want it back together asap but also desire to have any benefit I can get while it's stripped down the to cam.
 
#12 · (Edited)
What you are thinking is correct the cam gear is 72 teeth so 360 de. 72=5 meaning 5 degrees per tooth.You should be able to see the marks on the inside of the IP gear wear the gear was riding before on the IP shaft (key-way)if your carefully and lucky try to line it up add 1 tooth and it will put you at 17-18, . The pump turns the CW as does the motor the cam turns CCW so it should 1 tooth CC .I forgot to dubble the 5 degrees do to the pump turning half speed.
 
#14 ·
yes, time it the proper way LOL

Like mentioned, its entirely possible that your timing pin for the gear is out to lunch now. but you can use the drop valve method to get the engine pretty damn close to TDC (as close as it matters for a stock setting) and use the timing pin in the pump to set the pump where it needs to be.

Their are a couple methods of adjusting timing (see tech articles), all of them are going to require more than just the basic tools most people have. Easiest method for most is to use the plunger lift method. you can make a dial indicator holder out of an old oilpan plug, then you just need to go out and buy a LONG stem dial indicator and a delivery valve holder socket.
 
#16 ·
I just talked to a buddy of mine of really knows his stuff. After speaking with him I realize exactly what you guys mean. I read over all that you guys had posted and it just makes sense now. I was just so confused the the pumps on the 1st gens and got it all mixed up.

Thanks for putting up with my lack of knowledge.

Side question though...when I initially pulled the gear of the IP I could have swore the shaft didn't move. Do you guys think I'm safe just reinstalling everything how it was and hoping for the best or do you think the pump shaft moved after the gear that held it in place was removed? I was told that if it moved just a tiny bit it wouldn't be a big deal.

Once again, you guys are great and I really appreciate the time you take to teach people like me (I can't be the only one here that gets this confused).
 
#17 ·
Bump. Sorry but I'm about to put her together and just don't feel right doing so without knowing about the IP shaft.
 
#19 ·
thank you much illflem. I recall seeing this diagram but it was under a different post so it never registered. The first diagram show a pin, is this the one located on the backside of the timing gear case? If so, where is the second one located?
 
#21 ·
i saw it in the diagram and get how it works I just didn't know exactly where to locate it. I do now. Thank you very much.
 
#23 ·
fantastic! thank you, that is much better. New gear case comes in around noon tomorrow. So I hope to have her assembled and timed by tomorrow night. Appreciate all the input guys. You made my KDP issues seem like no big deal, thanks.
 
#24 ·
One of these days someone is going to engineer (cough cough*** rig up) something with a little adjusting screw that rotates the shaft in relation to the gear...

Adjusting the timing becomes as easy as pulling the filler neck, turning a screw, and trying it out!
 
#25 ·
:drool2: thecheese, you figure that out and I'll put off putting my truck together until you got it. I'll be awaiting your reply :hehe:
 
#27 ·
not for me. I'm guessing the second time it'll go quicker. Right now I'm sitting on a bucket staring at it wondering how I could have gotten in so deep. I hope a few weeks down the road I'll be reply to others telling them how easy it was for me :)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top