CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
76 CCDRW...Cummins noises
- Thread starter 76zimmer
- Start date
DEMON44
Low-Tech Redneck
Have you seen if the stock cover clears the new gear?
Very puzzling situation now:
When we timed the pump with the adjustable timing gear the first time it went by the book, and we ended up with 15.75* and 4.85mm plunger lift.
Now when I check the plunger lift I'm getting almost 12mm of lift. I've checked it multiple times and its always close to 12mm of lift . What am I doing wrong?
The plunger starts to lift abot 50* BTDC and is still "off its base circle" and ramping down when the exhaust valve has opened and closed and the intake is almost fully open???
When we timed the pump with the adjustable timing gear the first time it went by the book, and we ended up with 15.75* and 4.85mm plunger lift.
Now when I check the plunger lift I'm getting almost 12mm of lift. I've checked it multiple times and its always close to 12mm of lift . What am I doing wrong?
The plunger starts to lift abot 50* BTDC and is still "off its base circle" and ramping down when the exhaust valve has opened and closed and the intake is almost fully open???
Last edited:
Exhaust has closed and intake is open when plunger finally seats again. At that point the piston is about 230* ATDC.
I have moved the adjustable timing gear 14 degrees and still come up w the same gross lift.
I have tried to push the plunger down but it seems to be seated while taking these readings and not floating to give an erroneous number.
Any ideas where I'm going wrong here?
I have moved the adjustable timing gear 14 degrees and still come up w the same gross lift.
I have tried to push the plunger down but it seems to be seated while taking these readings and not floating to give an erroneous number.
Any ideas where I'm going wrong here?
DEMON44
Low-Tech Redneck
The valves on #1 should not be moving when you're setting injection. 1 must be on compression stroke so valves must be closed. #1 tdc on compression will have valves on #6 on valve overlap.
Right Luke I got that part; #1 @ TDC firing (confirmed by the alignment marks on the crank/cam, and the pin in place on the back of the cam gear) the valves are closed...I've gone through the cycle (clockwise rotation) many times to confirm that. The issue is I'm getting almost 12mm of lift from the plunger, and about 280* of duration while the plunger is off its base circle...it starts to lift about 50*BTDC and doesn't seat again until 230*ATDC; at that point the exhaust has opened and closed and the intake is open again for the next intake cycle.
DEMON44
Low-Tech Redneck
You don't need to worry about the total stroke of the plunger. The rack controls when injection stops. The plunger and move long after the spill port opens and injection halts.
DEMON44
Low-Tech Redneck
Ok. Do this.
Back the engine up BTDC like quarter turn. Approach tdc slowly. And stop TDC #1 compression. Set dial to somewhere in the middle of stroke. Number doesn't matter. Back the engine up again until the dial stops moving down then continue far enough to ensure you eliminate lash in the geartrain before start going forward again.
Before you travel forward again. Stop and reset dial to a zero. Turn engine forward towards TDC slowly. Geartrain is loaded before dial starts to move or you will not be accurate. Travel to TDC slowly and stop TDC.
That number is your plunger lift.
Back the engine up BTDC like quarter turn. Approach tdc slowly. And stop TDC #1 compression. Set dial to somewhere in the middle of stroke. Number doesn't matter. Back the engine up again until the dial stops moving down then continue far enough to ensure you eliminate lash in the geartrain before start going forward again.
Before you travel forward again. Stop and reset dial to a zero. Turn engine forward towards TDC slowly. Geartrain is loaded before dial starts to move or you will not be accurate. Travel to TDC slowly and stop TDC.
That number is your plunger lift.
I'll give it a shot when I get home in the am Luke, I'm just baffled why it went by the book the first time around and now its so much different. Is it hydraulic pressure in the plunger that is causing so much lift? If so why didn't it do it the first time around....Thanks for the help, I"m just trying to understand whats going on here!
DEMON44
Low-Tech Redneck
I'm not sure why it would have changed. That's not normal. What I described is exactly the timing check procedure. Don't worry about the camshaft or valve timing. As long as you are 100% sure it's #1 compression. Do what I described will be your injection timing plunger lift. In its current state. Is there a key way in your pump shaft?
will do Luke...and Yes it is a keyed hub on the pump shaft...can't see it in this pic, but this is the setup.
After playing with about 5 different holes on the adjustable gear and replacing the timing pin for the cam gear I ended up @ about 5.0mm lift at TDC. I think that works out to be 16.5* timing...about 2.5 from what stock calls for.
The timing pin housing seems to have a bit of slop in it. The bolts are much smaller than the holes, allowing it to move around (perhaps enough to make that 2.5* bump negligible)
I moved the cam gear into position and pushed the pin in and held it there while tightening down the retainer screws into the backside of the gear housing. Seems that is a piece that could be made more precision....is there something better out there to find TDC short of pulling an injector to do a piston stop method?
The timing pin housing seems to have a bit of slop in it. The bolts are much smaller than the holes, allowing it to move around (perhaps enough to make that 2.5* bump negligible)
I moved the cam gear into position and pushed the pin in and held it there while tightening down the retainer screws into the backside of the gear housing. Seems that is a piece that could be made more precision....is there something better out there to find TDC short of pulling an injector to do a piston stop method?
DEMON44
Low-Tech Redneck
Your not supposed to move the timing pin housing. There is slop in it on purpose. There is a procedure to set that pin housing for absolute TDC. Then it's not supposed to be moved. If it's moved it has to be reset.
