Engine/Transmission (1998.5 - 2002) adjusted valves wow

[Don Tanklage]

how short is the duration in the stock cam???



cant believe you can adj 3 cyl worth of valves with the camshaft in ONE position and not have some of the tappets really close to a ramp, if not on it!



♥ when the int closes: adj the ex ♠ when the ex opens: adj the int ♦ that puts each tappet pretty much right on the heal of the lobe



don



ps - has anyone set the clearance cold and then checked it hot to see which way it goes and how much it changes? i think it grow with heat in an alum motor and decreases in a steel motor. dunno, i never adj valves cold cuz nothin i am ever driving stays cold...

 

[Mhannink]

how short is the duration in the stock cam???



cant believe you can adj 3 cyl worth of valves with the camshaft in ONE position and not have some of the tappets really close to a ramp, if not on it!



♥ when the int closes: adj the ex ♠ when the ex opens: adj the int ♦ that puts each tappet pretty much right on the heal of the lobe



don



ps - has anyone set the clearance cold and then checked it hot to see which way it goes and how much it changes? i think it grow with heat in an alum motor and decreases in a steel motor. dunno, i never adj valves cold cuz nothin i am ever driving stays cold...

the procedure for adjusting the valves as i do it is what cummins detroit cat and any other mechanical valve setup use in an inline engine. i am a cat tech and honestly believe if its good enough for cat its good enough for anyone else. yes when you do three cylinders you are getting some close to the ramp but they are still on the heel and fine for adjusting.



as far as clearances yes they close up on all these engines. aluminum i think would close up more since all metal expands as it warms up.



as for adjusting cold the specs you see are for a cold engine. if you did it hot your gap would be too big. what cummins is trying to accomplish is close that gap to next to nill when its hot to gain optimum perforance. when its cold and you set the specs . 006 int . 010 exh. min. . 010 int. . 015 exh. is spec. i like to adjust tight so that its making the most out of the cam thats in there.



another way to adjust the valves the flat rate way as i call it is the same as listed about but instead of doing 1 and 6 you find the next closest one to tdc adjust put it on its companion and adjust again and your done.

 

[Don Tanklage]

i think in a alum pushrod motor the block and head grow more than the steel valve and pushrod so they get looser but it doesnt matter cuz these blocks are not alum.



i dont have a book, just started messin around with the truck a couple of weeks ago, pulled the covers hot (180 h2o) (yea, ouch) and set them at a tight 6 and 10. figured if that is good enough for 13,800 rpm bike motor it will work for 3k with a heavier valve and a weaker spring. the idle got smoother, didnt really notice a diff at wot tho...



don



ps - speaking of springs: my buddy sent me a 12v stock spring. said the inst ht is 1. 940". does this sound right to you? the spring is only 75# on the seat if this is correct. then again, i think these springs had just over 100k on them. what i am wondering is what is the installed height and seat pressure of the "60 pound" 12v springs??? (i am sponsored by a valve spring distributor and want to see if they can match something up in a single, maybe a single w/ a dampener for under 20 bucks ea)

 

[Mhannink]

you know i havent done enough work to really look at the spring specs. so i cant tell you one way or the other wether its right or not. as for the alum. block your theroy sounds valid but as you said these arent alum. so its a moot point. as for adjusting hot if it works for you thats fine i personaly just dont like it to me it seems like it would be too tight but whos to say.

 

[Don Tanklage]

as for adjusting cold the specs you see are for a cold engine. if you did it hot your gap would be too big.

too loose...

as for adjusting hot if it works for you thats fine i personaly just dont like it to me it seems like it would be too tight but whos to say.

too tight...





tell ya what... tomorrow i will pull the #1 & 2 covers and see where they are when stone cold. i adjusted them hot 6 & 10 and havent drove it much so we can see just how much difference temp makes and in what direction



don

 

[Bob4x4]

Since hot will vary you will not get a constant # Hence the predictible(less than 140 degrees)cold spec.



Bob

 

[Forrest Nearing]

going too tight is a good way to burn an exhaust valve, especially if the truck is cranked up

 

[I-6DZL]

Going too tight is also a good way to eat up a cam and lifter. Or if you're lucky just bend a push-rod. I wasn't so lucky i guess. I can't blame the valves being too tight on eating a lifter and cam, but i also can't explain it any other way!



Just do what cummins says and drive happy, instead of working mad!



Curtis

 

[Don Tanklage]

Since hot will vary you will not get a constant # Hence the predictible(less than 140 degrees)cold spec.



Bob

not necessarily bob, if you get the thing to 180, do two cyl's, drive it again to make sure you are still 180, do two more, etc, imo your clearances are going to be wayyyy more accurate than using a 2 postition method cold



imo

 

[Don Tanklage]

going too tight is a good way to burn an exhaust valve, especially if the truck is cranked up

sure forrest, if you incorrectly adj the valves, and leave one hanging open it will burn. but for a valve to be that tight it would have less than zero clearance and with a valve adj that way 1) that cyl would have no compression (motor would not be running on all 6 cyl's and i would think you would hear that?) and 2) there would be no room between tappet and lobe for oil. the cam would go flat quick style...



right?

 

[Don Tanklage]

Going too tight is also a good way to eat up a cam and lifter. Or if you're lucky just bend a push-rod. I wasn't so lucky i guess. I can't blame the valves being too tight on eating a lifter and cam, but i also can't explain it any other way!



Just do what cummins says and drive happy, instead of working mad!



Curtis

you sure can blame it on that - i have seen it happen. if there is less than 001 clearance the valve will still close (if you have sufficient seat pressure) but as i said above there is not enough room for oil, or enough oil anyways...



dont know about bending a push rod or bending a valve - min valve to piston clearance is determined by a few different variables but it is almost always greater than . 050". so having a valve a few thou tight is not going to cause interference.



if i did what cummins said all your 2nd gen trucks would be blowing by me when i was climbing the grades... . and that is not the case!



lol



don

 

[Forrest Nearing]

P/V really isn't a concern w/ a stock cam, but with a hot truck, you want to make sure that you've got that valve seated so it can cool off!

 

[Don Tanklage]

forrest, at 1800 rpm with 75 lbs of seat pressure and a really short dur camshaft how much clearance do you need to know that the valve is closing?



(also, do you happen to know the typical installed valve spring height on these heads??? one that has not had a valve job done on it)



looks like going from 60° to 180° only tightens the valves up 1 or 1. 5 thou



(just broke out the tweaker light and rechecked them all)



i had set them at 6&10 hot and now the majority of them were at 7&11 cold. you guys got me nervous so i made sure they were all above the min spec. even set the rear two cyl a couple thou loose (8&13).



I THINK YOU GUYS WOULD BE SURPRISED IF YOU USED A 6 POSITION METHOD TO RUN YOUR VALVES. THINK YOU WILL FIND SOME A LOT LOOSER THAN YOU THOUGHT THEY WERE...



don

 

[Forrest Nearing]

Oh, I'm sure you're fine, you just don't want to run into that point where the valve is just barely seated and not transfering heat to the head casting properly.



I always set each valve when it's on the base circle

 

[Don Tanklage]

i hear ya forrest. if they aint on the seat there is no where for the heat to go



don



have you ever rebuilt one of these heads?



still curious about spring ht



guess i can try to meas w it together but that is not as accurate



if someone gives me the ht i can put together some springs for these things, and do it cheap...

 

[Bob4x4]

VALVE SPRINGS

INSPECTION

Measure the valve spring length. The approximate free length is 60 mm (2. 36 inch) with the maximum inclination of 1. 0 mm (0. 039 inch)



Measure the valve spring force. 359 N (81 lbs. ) is the minimum acceptable load required to compress the spring to a height of 49. 25 mm (1. 94 inch)



That what you were looking for ?



Bob