What the heck???

Brent Mills · #1 (**permalink**) 08-31-2003, 12:16 AM

I have adjusted the valve lash 5 times and it keeps going outta whack!

First I adjusted cold .022 int .024 exh drove it for about 5 miles....Sounded loose, so I adjusted same hot. Sounds/runs great! 10 miles later, running funny, lots of valvetrain noise....Adjust again, thinking maybe the damn thing wasn't warm enough the last time (slack in ALL), so I adjusted again. Runs great, sounds great, and go for a drive about another 10 miles or so, starting to run differently, more valvtrain noise.....Adjust again (slack in ALL), go for about 30-40 miles runs and drives great at least half the way, but by the time got home, running a little funny and valvetrain noise.....Adjust again tonight (slack in ALL). (Also, the lifters were all perfect before putting the new rockers and pushrods in.)

What the heck! Am I really losing my cam on all lobes or what? Something is really fishy, and the jam nuts are all tight when I go to adjust. I'm really confused and pissed!!!

Using Precision oil pumps rockers, stands, spacers, and good ball/ball pushrods. SON OF A.....

By the way, I'm adjusting the valves by starting with #1 cyl, when the exh starts to open, adjust the intake (do the same for all cyl's) then back on #1 when the intake is almost closed, adjust the exhaust (do same for all cyls).

Turk · #2 (**permalink**) 08-31-2003, 12:17 AM

NOT AGAIN!!!

TURK

Brent Mills · #3 (**permalink**) 08-31-2003, 12:22 AM

I'm cursed.

Excaliber · #4 (**permalink**) 08-31-2003, 03:03 AM

????? Some break in and settling of the valve train I can understand, but this sure does sound excessive.

Valves pounding themselves into the seat would make the lash tighter, so that's not it.

Cam lobes could be suspect, but gimme a break, it aint gonna change as much as you describe (unless your just totally cursed and your on your way to a flat cam,,,,,nah, can't be that).

Lifters going flat all ready? Yeah right like all 16 were bad out of the box? Hard to imagine that happening!

Rocker arms are rapidly wearing on the shaft (you ARE getting lots of oil there I hope)? Push rod rocker arm ends are "seating" or rapidly wearing out? Hmmm,,,,theres a possible area to look at. Adjustment nuts backing off? Not likely as you indicated they were tight. Valves "sticking" in their guides?

Thinking,,,,,,,OK,,,I GOT IT!!! Your not adjusting the valves using a "scientific" methodology. Your ASSUMING it's OK to adjust the exhaust valve by "guessing" it's position based on the position of the intake valve, and vice versa. That means you may not be accounting for possible cam shaft valve over lap, or are "guessing" inaccurately. This is potentially a HUGE variable that would change EVERYTIME you adjust the valves! You cannot ASSUME the exhaust cam lobe is at the bottom of it's stroke based on when the intake valve "just starts to open" or whatever. Your now at a place where you HAVE TO BE SURE.

Many of the old "Motors" and "Chiltons" manuals referenced an EXACT way to determine WHEN it was OK to adjust valve such and such. Like, Exhaust on number 3 cyl is down, then adjust intake valve on number 6 and 8 cyl, etc. etc. It's like a "matrix". You could write it out if you think about the fireing order, etc. and make your own matrix. But it MUST be written down SOMEWHERE all ready????

Watch out for the valve over lap in this equation!

Ernie

427 S/O · #5 (**permalink**) 08-31-2003, 06:21 AM

Brent, I used a dial indicator (MSC part# PW7644009 about $25.00) to set pistons at absolute TDC, used and extension and slid it into spark plug holes, then marked the harmonic balancer. I did this on each cylinder and then adjust lash, I've never used your technique?. Checked lash every 2000 miles and still good.
After setting first four cylinders, marks will line up on remaining four. Hope this helps.

Woodz428 · #6 (**permalink**) 08-31-2003, 06:22 AM

You didn't say how old the rockers are, but if the adjusters are interference fit like the OEM ones, is it possible they just aren't holding adjustment?

Ron61 · #7 (**permalink**) 08-31-2003, 06:45 AM

Brent,

Sorry to hear that you are still having this problem. I believe you said in an earlier post that you have replaced all of the valve train components with brand new stuff. Rocker arms & etc. Like Ernie said, it is hard to imagine 16 bad new lifters and a cam would not normally wear off the same on all lobes. However since this seems to be turning into the motor from he--, I am not sure what I would do next. I like 427/SOs idea but if this keeps happening maybe an exorcism. You never changed heads and cam did you ? Have you talked to George Anderson or Tom Lucas about this ? One other thought and this is really reaching. Have you checked the height of your valve springs and their strength before installing and then after running them for a while. Could they be compressing just a little bit and binding at all after getting hot ? Just a wild guess here but the way things have gone I wouldn't be surprised at anything you find. I am sure that after all of this you have checked the oiling system completely and have plenty of oil. I don't remember, are you using roller rockers and lifters ? If this happens again in a few miles what about taking a lifter out and looking at it to see it it shows any strange markings.

Ron

RICK LAKE · #8 (**permalink**) 08-31-2003, 07:33 AM

Brent go back to the beginning and check the basics valve spring binding, oiling to the pushrods, ck for blueing, binding of the rocker body to the pushrod, you have the oiling holes facing down? What heads and block do you have. What head gaskets are on it? Size of cam? When the motor gets hot you may have spring binding and bottoming out the rocker. Does the clearance disappear after the motor cools down of great larger, or stay the same??? Need some answers please.

Maybe the motor doesn't like Calif. or the govennor choises.

Rick Lake

PatBuckley · #9 (**permalink**) 08-31-2003, 08:12 AM

Brent-

When you check the valve adjustment after they get noisy, what clearances are you seeing?

Solids do run noisy, it is a characteristic.

Pat (who doesn't know his ass from a hole in the ground most of the time either!)

Brent Mills · #10 (**permalink**) 08-31-2003, 10:36 AM

More information that answers a bunch of stuff above.

Pulled the driver side rocker shafts & arms....All looks good, no blueing anywhere, wear seems pretty much non existent. Pushrod balls are not worn on either end. Decided to pull the distributor and see if I could get a lifter out, and did get the #5 exh which I have adjusted several times (like all of them), and the lifter appears to be in fine shape.

As for the adjustment, well, it's possible but not likely that is where the problem is, because it seems to run fine for a while, but ultimately begins to run differently. I mostly notice it in the idle, and the valve train gets louder. It also would not explain why each time I have had to take up slack.

This is not a big cam (about .540 lift, 240 duration @50, and 114).

As for coil binding, I'm not noticing any, and I should notice that in the feel of cranking the engine by hand, right?

Is it possible that with new rockers and push rods, that stuff is just working it's way together (sort of a break in thing)? Seems odd to me.

Pat, I didn't think to check what the clearance was after it gets out of whack, but it's considerable, as I can move the rocker by hand and know there's too much clearance. As for warm to cold, it seems to vary by .002 - .003 across the board (checked that this morning after I adjusted warm last night).

Rick, the oil holes are down, c4aeg heads, not sure on the head gaskets.

LateApex · #11 (**permalink**) 08-31-2003, 10:51 AM

Quote:

Originally posted by Brent Mills

Pat, I didn't think to check what the clearance was after it gets out of whack, but it's considerable, as I can move the rocker by hand and know there's too much clearance. As for warm to cold, it seems to vary by .002 - .003 across the board (checked that this morning after I adjusted warm last night).

Brent, if they are spot on when you adjust, and then out of whack after a ride, my guess, and this is only a guess, is that prehaps the jam nuts are not tight enough and letting the set screws move while you drive perhaps. I know you said they are tight when you recheck, but how else could the clearances change after you drive??

Brent Mills · #12 (**permalink**) 08-31-2003, 11:10 AM

Quote:

Originally posted by LateApex

Brent, if they are spot on when you adjust, and then out of whack after a ride, my guess, and this is only a guess, is that prehaps the jam nuts are not tight enough and letting the set screws move while you drive perhaps. I know you said they are tight when you recheck, but how else could the clearances change after you drive??

Good points. Thought this myself, but the adjusters are actually lower due to adjustment (originally the top of the adjuster was above the crown of the lock nut, and now they are about level). That's what scares me.

Cracker · #13 (**permalink**) 08-31-2003, 11:28 AM

Once again... I have a 428 w/ Webers on...

Just kidding - make sure you don't change the lash when your locking the jam nut down as well. I bought the nifty tool for Summit that is a integrated two piece design that helps with the control of both stud/nut. Best wishes!

Brent Mills · #14 (**permalink**) 08-31-2003, 11:31 AM

I have been pretty careful about that. Sort of a pain, but it's been pretty close. Again, the thing runs well for a while, but then lots of clatter and doesn't run as well. Tighten it up again, and all seems ok for a while, and then noise and doesn't run as crisply.

What a pain in the arse!

Excaliber · #15 (**permalink**) 08-31-2003, 11:39 AM

Man, we need George (AKA NIMBY) or some other fine builders to weigh in here! This really IS a mystery!

Ernie

GEORGE ANDERSON · #16 (**permalink**) 08-31-2003, 12:44 PM

Hi Brent.....I'm off for Dirt Track races in a little while...but a thought or two...
I would be interested in seeing the pushrods....you're absolutely certain nothing seems to be wearing out but we know that slack is going somewhere....
When pushrods are built, a machined inside bore is made for the end ball components to be installed into....if perhaps these pushrods wern't all the way pressed in......if perhaps these pushrods wern't all the way pressed in
then the hammering of the motor would force them deeper making the lash get loose....
I'll be back after midnight tonight...I'll be interested in the findings by then...

George

Brent Mills · #17 (**permalink**) 08-31-2003, 12:52 PM

You know, I'm a complete butt. I hope I haven't burn my bridges with George, as he still has my old engine which I'm trying to get the money to get it built through suit from the previous builder, as the last builder was bogus. And because I was in a hurry again to get the stupid thing on the road this year, I went relatively locally with the new engine I found, instead of through George. I'm just an impatient idiot. I shouldn't even own a damn car, let alone a Cobra.

PatBuckley · #18 (**permalink**) 08-31-2003, 12:55 PM

Brent -

You may want to also drain the engine oil and check for signs of something wearing.

Pat

Eljaro · #19 (**permalink**) 08-31-2003, 03:09 PM

Brent,
I had a similar problem with valve lash inconsistent adjustment, and it was the pushrods which were touching the holes in the intake manifold. So I would adjust the lash , actually bending the rod against the side of the hole in the intake manifold. The pushrods would end up bending or wearing off the aluminum in the intake manifold holes, or wearing off the cup against the ball at the top. Next time around the lash adjustment was off on many of them.
When I got a new intake manifold (Edelbrock Performer RPM) I had to grind every one of the holes to prevent pusrod contact with them.
You can see that by yourself in a minute.Take the valve cover off, turn the engine over and see if you can turn the pushrods by hand and see if they rub against the hole in the intake manifold.
Just a suggestion, after everything else seems to be ok. in your engine.
Good luck!

Brent Mills · #20 (**permalink**) 08-31-2003, 04:49 PM

Just got towed home.

Driving along on the highway back to my place (went for a little 5 mile run to see if I finally got it) and I was starting to hear a bit more clatter from the valvtrain so figured the problem is out of my capabilities to deal with. A little miss....a second later another little miss, getting ready to shut her down, and it took care of all that for me. Done....all she wrote....Didn't hear anything mechanical break, but who the heck knows. I'm finished.

Thought it might have at the distributor gear or something, but it didn't. Hit the throttle and I see gas squirting into the chambers...Haven't checked the electrical, except to say that nothing has changed and other elictrical is fine. Oil pressure was good (70-75 on hwy), and temp was 185-190.

Pulled valve covers again, checked clearance on some of them, and they're way off again. .035 or so. What the heck, over?

Why?



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