Valve Adjustment and Timing

[hotram03]

I was reading another thread on here pertaining to this and was wondering, I thought the valve adjustment was the timing of a diesel? So checking the timing on what and how, if adjusting the valves, only adjust the valves and not the timing too, do you need any special tools for checking the timing?

 

[DValentine]

The timing you ask about pertains to the injection cycle, valve lash adjustment just to the valves themselves.

To simplify things I will say that they are seperate, but in reality they are connected. They are connected by the gears covered by the front cover.



The injectector pump is rotated back and forth on the engine block in realtion to number one piston at top dead center. The injection cycle happens so many degrees before TDC. (Do you remember setting timing on a gas engine with a distributor?)

You might have read about determing where top dead center is by watching the rocker arms move (or not) on number 1 and number 6.



Valve lash is set such that as the parts get hot, as the engine runs, the lash (slop) gets less , but not to tight.



I know this is a simple explanation, if you want more detail, ask again and I, or some more knowledgible will reply.





Dave

 

[hotram03]

so how do you check and then set timing, do I need to set valves and timing at the same time or can I go ahead and adjust the valves?

 

[cojhl2]

Unless you have one heck of a good reason,, you dont screw with the timing. It stays set and is not a periodic maint issue!!



Valve lash a different story. Should be done about every 30 to 50k.

 

[DValentine]

To make a long story short, Guys have found that the factory setting (degrees before top dead center) that begins the injection event can be a little behind (late) and that an advanced setting can positively affect the running of the engine. Those looking at things from a emissions standpoint will disagree. The advancing or retarding of the timing changes the emissions output.

There are two ways I know to check your injection pump. A metric dial indicator ( the most accurate) or putting your engine on TDC number 1 cylinder and making sure the locking pin will engage with the injection pump gear.

Search the archives for these and better directions.



The valves can be adjusted regardless of what the injector pump is doing. Some guys turn the engine over using the alt. nut on the pully. Cummins sells a tool that sits in a hole on the rear of the engine and meshes with the flywheel starter ring. I can't remember right off, but I think the setting is . 010 on intake and . 020 on exhaust.



Dave

 

[Sri Ram]

Valve lash a different story. Should be done about every 30 to 50k.

my 91 manual suggests every 24k…?

 

[cojhl2]

Thanks SriRam forr looking that up and giving an accurate number.



Mine was just a guess but it is good to have the correct facts.

 

[LEggers]

This is the way I was helped in doing my valve lash the first time and it works very well.

Print it out and have fun. .



MAKE SURE YOU PULL YOUR TDC PIN BACK OUT BEFORE YOU START TURNING THE ENGINE WITH YOUR WRENCH OR YOU WILL BREAK IT OFF!!!



http://dodgeram.org/tech/dsl/valve_adj/12_valve.html

 

[JLEONARD]

my 91 manual suggests every 24k…?

Yea right. I bought mine with 87k on the clock... at 160k now and I've never pulled the covers.

I do have a set of gaskets on the shelf though... . one of those "round tuit" jobs.

 

[cojhl2]

Now that we're fessing up,, I did mine about a year ago at over 500k. To the best of my knowledge they were only done one other time at I think at about 200K when a crank seal was replaced and at that time new berings were spun in.



My pickup was used in construction the first 10yrs of its life by my neighbor and sometimes employer. So it has not had an easy life although it always had the normal lube maint done very religiously.



In real life if you had to set valves every 20k or so these OTR tractors would have to be checked every month. .



But I guess its still better to do stuff by the manual.

 

[TKingsbury]

I checked mine a couple weeks ago, no adjustment necessary. I think the po said he had them done sometime before I bought it, so it has at least 30k since last done. On the other hand, Pepecat was there and we did his too. And boy did it need it! Someone has done things to his engine for sure, but what exactly was done is unknown. A couple of his were right on the money, most were a bit out, and #1 was quite a ways out. I had a . 026 in the exhaust and probably could have gone 1 or 2 thou further if my feelers went that far.

Travis. .

 

[pepecat]

roger that. thanks again travis for hosting the tune up party. I took the truck down to L. A. and back last weekend, roaring at 75 mph or so the whole way and it's running great.

Nick

 

[TKingsbury]

Good to hear.

Travis. .

 

[Sri Ram]

Yea right. I bought mine with 87k on the clock... at 160k now and I've never pulled the covers.

I did mine at 235k and all were loose. Who knows how long it had been…

 

[LEggers]

I did mine at 235k and all were loose. Who knows how long it had been…

Did mine at 185K and found some real loose ones also...

 

[cojhl2]

This is kinda interesting!! I always thought they tightened up cause the seats wore down faster thatn the stems.



As a matter of fact when I did mine about a year ago the reason I did it was cause I could hear a poop poop poop from the air intake,, which I think was caused by one of the intakes too tight and not letting the valve close.



Anyway the noise went away after adjustment.



Had that been an exhaust valve it would have been badly burned. So,, the moral is 21k might be a little conservative but these long milages are not good either!



This all brings up the original question. On these newer engines isn't the injection done by a cam driven injector. Does that mean timing should be set periodically also?

 

[LEggers]

This is kinda interesting!! I always thought they tightened up cause the seats wore down faster thatn the stems.



As a matter of fact when I did mine about a year ago the reason I did it was cause I could hear a poop poop poop from the air intake,, which I think was caused by one of the intakes too tight and not letting the valve close.



Anyway the noise went away after adjustment.



Had that been an exhaust valve it would have been badly burned. So,, the moral is 21k might be a little conservative but these long milages are not good either!



This all brings up the original question. On these newer engines isn't the injection done by a cam driven injector. Does that mean timing should be set periodically also?

I relate the loose valves to a rocker getting warn out or a cam that has a small amount of wear but also agree with you about the tight valve senareo. .

 

[cerberusiam]

This all brings up the original question. On these newer engines isn't the injection done by a cam driven injector

No. Injection on the HPCR is electronically controlled by the ECU. Injection timing, duration, and pressure are all ECU set and ECU activated.



All the jerk pumps operated the same way, pressure activated injector pop. Pressure was preset depending on the system. Timing and duration was controlled by the IP in conjunction with the injector pop pressures.

 

[BushWakr - RIP]

Hey 'Cerb..... you "missed your calling" I think. Awesome source of help and info bud... . glad your in here...



pb... .

 

[cerberusiam]

Pastor, I thank you for the accolades.





The only reason I know anything about this subject is I KEEP BREAKIN' STUFF!!





:-laf :-laf