cLAYH

Can someone look at them and tell me if I'm wrong...... I did my valves today and while the pics were great something didn't make sense to me.

For starters I don't have a BDC mark on my timing cover, and you don't set the valves at TDC and BDC on number one. You set them at TDC, compression stroke of number one and then roll the crank over 360* to TDC exhaust stroke of number one(or TDC compression stroke of number six). Remember it takes two full revolutions of the crank to turn the cam once.

I've never used BDC center as a reference to set valves on anything!

On the upside the engine is much quiter now! Don't know if it helped performace any as the new RV275 nozzles went in at the same time and there is too much snow coming down right now to get a good test run in. Did seem a bit more snappy though.

BCSCUMMINS

You should have your top and bottom marks behind your blow by hose. Take the hose off and the round can will unthread. The nut on the injector pump will have a mark on it. There will be two marks on the cover. One at 12 and one at 6.

jrs_dodge_diesel

Yep, the TDC mark is on towards the top of the engine, and the BDC mark is towards the bottom of the engine, 180° from TDC. Both TDC and BDC marks are embossed into the timing case.

That is a tad confusing now that I think about it. Because when the gear is lined up with the BDC mark, #1 is at TDC of its exhaust stroke. Maybe the TDC and BDC marks are in reference to the fuel pump drive gear, not to any particular cylinder?

cLAYH

I cleaned the cover with some brake clean and a 3m scrubby, I then used a mirror and flaslight but could see no BDC mark. However if it is 180* across from the TDC the number one cylinder is not at BDC but at TDC of the exhaust stroke.

The whole BDC is not making sense to me.

In the end I did my valves as I was trained to do for any 4 stroke, set engine to TDC on the compression stroke on cylider number one. Set valves. Rotate crank 360*, engine is now on the exhaust stroke of cylinder number one. Set the remaining valves. At no point are the valves set with cylinder one at BDC.

BTW after I set the first set of valves and rotated the crank 360* the mark was now pointing straight down, 180* from the TDC mark. 1 revolution of the crank=1/2 a revolution on the pump gear. So setting the valves with the mark at TDC and then 180* away from TDC is correct, not sure what the BDC is about as BDC would be 90* from the TDC mark.

Tate

FWIW, there is only a TDC mark on my timing case at 12 o'clock, but nothing at 6.

Grider Pirate

[QUOTE=cLAYH;1439440]
In the end I did my valves as I was trained to do for any 4 stroke, set engine to TDC on the compression stroke on cylider number one. Set valves. Rotate crank 360*, engine is now on the exhaust stroke of cylinder number one. Set the remaining valves. At no point are the valves set with cylinder one at BDC.
QUOTE]
This is a six. That means a piston will come to TDC on the firing stroke every 120 degrees (360 x 2 [because it's a four stroke] / 6 [because of crank layout to have evenly spaced firing with 6 cylinders]) To set the valves at TDC of the firing (compression) stroke ideally you would set #1 at TDC and adjust the valve lash for #1, then rotate the CRANKSHAFT 120 degrees and adjust the valve lash for #5, rotate 120, do #3, etc... (Firing order is 153624)
That's a PITA, and unnecessary.
The service manual makes no mention of BDC. It just shows a picture of the Pump Gear Timing Mark orientation.
By the factory book, with #1 at TDC,(the timing mark will be straight up), set the intake valve lash on cylinders 1, 2, and 4, and the exhaust valve lash on cylinders 1, 3, and 5. Then, (as you did) rotate the Crankshaft 360 degrees. The timing mark is now straight DOWN. Set the intake valve lash on cylinders 3, 5, and 6, and the exhaust valve lash for cylinders 2, 4, and 6.
NO, those cylinders are NOT all at TDC. However, the cam followers ARE on the low points of the cam for those cylinders/valves indicated.
If you set the valve lash for #1 with it at TDC and rotate the crank 360, the set ALL THE REMAINING VALVES, some of them are going to be loose - a lot loose. #6, however, should be perfect.

Hillcountry

My understanding was that the termanology was just where the mark on the pump was The pump gear moves at 1/2 the revolutions so 360 on the crank is 180 on the pump. TDC is marked, but I guess BDC doesn't make sense other than the tab is pointed to the "bottom." I found the instructions to be very helpful though.

jrs_dodge_diesel

Thank you Hillcountry, I am the one that wrote it. I realize now that BDC is confusing. The TDC mark is labeled in the appropriate place. Somehow I got "BDC" stuck in my head when I wrote the article. I should have wrote something different.