Timing & Rocker question.

Discussion in 'The Garage' started by Nacho, Jan 9, 2007.

  1. Nacho

    Nacho Active Member

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    Right now I have my timing set at 17* and the car is running strong. I can hear my rockers and am not sure if it's pinging or not. I just filled up with 93octane to be on the safe side but I can still hear them, and they get louder under acceleration. I don't know if my timing is too high, since I was told that the optimum timing our 5.0s is 33* total and that you add 18* to your base timing and that's your total degrees. So I would be at 35*. Could it be that my timing is too advanced? Like I said, my car feels very strong and I have no driveability issues, it's just that the rocker noise makes me nervous.

    FYI, I have gt40 heads, e-cam, explorer intake, 1.7s, crane valvespirngs, new fms lifters, and just added some "new" pushrods (200 miles). I'm not comfortable with the noise my valvetrain is making. Our stock pushrods are 6.25 in length, should I get the 6.30 from trickflow? Please feel free to post any useful feedback. O0
     
  2. ryclef331

    ryclef331 Well-Known Member

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    Whew...here we go.

    First thing that would be EASIEST is to back the timing down to like 8-10degrees and see if the noise goes away. If it does, it ain't your rockers. Roller rockers DO make noise but you should not be to hear them when you romping on it. Mine sound like a sewing machine when the car is at idle with the hook up but thats it.

    You pushrod length ISN'T going to have that sort of effect on it. Push rod length adjusts your rocker geometry or where the roller tip rides on the tip of the valve stem. With the lifter sitting on the base circle of the cam (valves closed) the tip should sit dead in the middle or JUST A HAIR towards the inside (towards the push rod) when everything is adjusted right. I took a black magic marker, blacked out the backside of the valve stem tip, installed and adjusted the rocker arm. THEN roll the motor over two complete revolutions to run it through its cycle....take the rocker BACK off and you can see the wear pattern where the rocker will ride. Dead center is optimal. You don't want it to go off the edge at all. If its too far "in" towards the push rod, you need a longer push rod. Too far away, you need a shorter one.

    Its sounds to me like your car is spark knocking. I don't think its detonation b/c your combo doesn't sound too agressive. Start with the easiest stuff. back the timing off....see if it goes away. If it doesn't, then check the geometry of the rockers.

    One more thing, do you have a custom chip burnt for the car? If so, they may have done something with the timing (bumped the tables). You can check for total timing. Pull the spout connector, hook up the timing light, have someone rev the car to 3 grand, and check it that way. It should read the 33 * you want. Are you running a MSD box? If so, what kind of timing light are you using?

    If I were you, I wouldn't drive the car hard until you're sure it is NOT pinging. You don't wanna rattle that motor to the point of destruction.
     
  3. Nacho

    Nacho Active Member

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    Thanks Ryclef. I just went ahead an orderd the pushrod length checker from summit just to be sure. I was planning on bringing the timing down to 10* and checking to see if it goes away this afternoon. So the optimum total timing is 33*, right? As long as it doesn't ping. The thing is that when I installed the 'new' pushrods, the noise decreased, but after several hard pulls, it came back. So that confuses me a bit. Also, the noise can't be heard inside or outside the car. You can only hear it if the hood is open and standing next to it at idle and when accelerated, does that sound like normal rocker noise? Several of my buddys with 5.0s also have rocker noise, like a sewing machine and I've been told that it's normal but I just don't want to dismiss it that quickly.

    First things first, back off timing and check. If the noise persists, check pushrod length and correct.

    I'm using a standard timing light from advance auto parts ($40). I do have an msd 6al box and did the a9l swap to avoid needing a chip.
     
  4. Nacho

    Nacho Active Member

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    Also, when I back the timing off, will the noise immediately die down?

    And let's say the noise doesn't go away, I should be able to run it at the same timing (17*) with no problems and just worry about checking the rocker geometry? So I ask again, I shouldn't go over 33* total timing right? Or is it ok if I do, as long as it don't ping? Which will be hard to tell with the rocker noise going on?
     
  5. ryclef331

    ryclef331 Well-Known Member

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    If its doing it at idle, I doubt its pinging. 32-36* total timing is ideal...depending who you ask. I'm guessing you have pedestal mount rockers if you're running GT40 heads. I'd make ABSOLUTELY SURE that you're adjusting them right and they aren't too tight. If you have them too tight they can force the lifter plunger too far down and the lifter will NEVER pump up. THIS WILL make a racket at idle. Double check that you've got them adjusted properly. I know its kind of a pain but try doing just the driver's side and see if the noise gets quieter. If you're hearing it at idle, I HIGHLY doubt its pinging. You're using a cheap-o timing light. That good with an MSD. A dial back light on an MSD is a no-no. MSD stands for "Multiple Spark Discharge" so this screws with the pick up of a dial back light. I learned that the hard way...thank God I went back and read the directions. Thats why I asked that question. Pinging at idle is pretty much NOT going to happen. Verify the valve lash and rocker geometry at the same time while you're in there. I bought a pushrod check when I built my stroker....truth be told, I didn't even use it. I did the magic marker trick. It was a lil shallow with stock pushrods. Pushrods come pretty much in + or - .100" I just went up .100" ...came out perfect.
     
  6. Nacho

    Nacho Active Member

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    Well you were right. It ain't pinging. I retarded the timing down to 8* and the noise was still there. I left it at 15* after messing with it for a while. I'm going to go through the rockers today. I'm not overtightening them, I'm doing 20ftlbs all the way around and am even considering doing like 24lbs just to see if that helps. You're saying that if I go from 6.25 to 6.300, it won't be worth it? Trickflow sells that measurement. So maybe just jump up to 6.350?

    Can you explain to me what you meant with that cheapo timing light and msd? Are you saying that I need to buy a better one or can I get away with setting the timing but unplugging the msd to do so?
     
  7. ryclef331

    ryclef331 Well-Known Member

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    No no ...You're doing the timing right. With an MSD, they fire the plugs MULTIPLE times below a certain RPM to ensure a full "burn." Well with dial back timing lights (the ones with the knob on the back you set to where you want it and line up the balancer to ZERO), these multiple sparks will make the timing show incorrect. When I timed my car with a Digital 6 Ignition and a Dial back light, I couldn't go past 1/4 throttle or else it was spark knock TERRIBLY. I used a cheap point and shoot light, found my timing to be like 34 degrees advanced ....NOT TOTAL timing.

    As for the rockers, retorque'em and see where on the valve tip they sit. Are the rollers to far inboard (towards the middle of the motor) or too far outboard (towards the fender)? You gotta know that BEFORE you order some pushrods.
     
  8. Nacho

    Nacho Active Member

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    That's why I ordered the pushrod length checker, don't want to order the wrong measurement. I'm a lil confused on how to check the rockers. You're saying to mark the exhaust and intake valve with a black marker on the lil part that goes through the spring (valve stem). After that turn the motor over manually and let the rockers go up and down a couple of times. If the marker stain is erased on the inside it means that the outer edge of the rocker is hitting it and I need longer pushrods, and if the marker stain is erased on the outer side of the the valve stem it means that the inner part of the rocker is hitting and I need shorter ones. Am I right? If I'm correct I'll do this today. I can just try one or two rockers, right? I don't have to go throught ALL of them? I tried to put it in lamest terms as possible.
     
  9. Nacho

    Nacho Active Member

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    Also, am I losing performance or hurting my motor if I take my car to the track like this?
     
  10. ryclef331

    ryclef331 Well-Known Member

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    I would run it it until its RIGHT.

    You're close with the marker trick to check it. It is NOT part of the rocker arm that wipes off the marker. The roller itself actually rolls across the valve stem wiping off the marker and showing you exactly where it will ride. If its not TOTALLY centered, thats not necessarily that bad. When you take the rockers off, if the back of the valve stem isn't all beat up and roller tip isn't gouged up, the geometry is probably fine and NOT causing the noise. I really think it might be the valve lash. Again, if they're too tight, the plungers in the lifters stay collapsed and bottom out and they WILL make a "tink-tink-tink" noise at idle. If they are WAY too tight, the noise won't go away when the oil pressure goes up.

    I have stud mount rockers so my install is a bit different but from a very reputable source, this is the procedure I use...with great success.

    To install pedestal mount rockers:

    1) For each pair (int/exh) be sure you rotate the engine so the lifters are on the base circle of the cam - this is very important. When you install the rockers, both valves must remain closed. Neither lifter can be on any part of the cam lobe - they MUST be on the base circle. Rotate the engine clockwise. Watch the pushrods for the pair you're installing. The exh will rise and fall; as it's about to 'close' (fall back down) the intake will rise. Keep rotating until the intake falls back down (closed) and both the intake and exhaust pushrods are the same height. You're now on the base circle of the cam at the beginning of the compression stroke for that cylinder.
    2) Install the rocker and bolt it down to zero lash. Zero lash is reached just when you eliminate the gap between the pushrod and the rocker and the valve stem and the rocker. Tighten with one hand and 'rock' the rocker with the other hand. Just when you reach the point that you can't rock the rocker anymore you're at zero lash.
    3) Now - put your torque wrench on it and tighten to 18-20 ft-lbs. while counting the number of turns it takes to reach that torque. You should hit the target torque between 1/4 turns and 1 turn. If it takes more than one turn, use a shim to raise the rocker. For each .030" shim you use, you'll reduce the number of turns to torque by about 1/4. If it takes less than 1/4 turn, or you have trouble reaching zero lash even with the bolt torqued all the way to 18-20, then you need longer pushrods.
    4) If all goes well on the install, crank it up. If some make noise let the car warm up completely. Then (unfortunately) go back through the install procedure with the components warm. That will usually quiet them down.
     
  11. Nacho

    Nacho Active Member

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    Thanks man for some more good info. O0

    I did the marker thing and they couldn't be any more centered. The roller tip marked off the black from DEAD center of the valve stems. I guess it's a good thing, don't have to worry about needing longer/shorter pushrods.

    I'm thinking it's gotta be the valve lash. I retorqued them down to 20ft lbs. but didn't check it after 0 lash. When the pushrods are the same length, then that's when they're at the base circle, right? Will this be the only time they'll be the same height? Any other way to tell if they're at base circle? Also, you said the noise is a 'tink, tink, tink' kind of like a small counter bell or what?  Cause my noise is nowhere near that, it sounds just like a sewing machine. I'm going to check the valve lash anyway, just for piece of mind.
     
  12. ryclef331

    ryclef331 Well-Known Member

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    Watch the pushrods for the pair you're installing. The exh will rise and fall; as it's about to 'close' (fall back down) the intake will rise. Keep rotating until the intake falls back down (closed) and both the intake and exhaust pushrods are the same height. You're now on the base circle of the cam at the beginning of the compression stroke for that cylinder.

    This is from above. The is the BEST way to set it and the only way. You may wanna keep a bit of finger pressure on the lifters as they fall to make sure they don't "hang up." The oil will make them stick a bit sometimes. The tink tink tink noise sounds ALMOST like an exhaust leak. As for going to the track with a collapsed lifter...no sir. Sounds like your pushrods are perfect. Pretty easy way to check them huh? When some one showed me that I felt like a dip shit..."why didn't I think of that?" If my car had an intake on it, I'd take a video of the under hood so you could hear the rockers "working" but they don't get louder as I rev.
     
  13. Nacho

    Nacho Active Member

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    Thanks for ALL your help man. Yeah, it was pretty damn easy. Even though I had to push the car in 5th gear cause I didn't have a socket for the crank bolt. It was a bit tiring but it worked. O0 If it's supposed to sound like an exhaust leak, then I don't think this is it either. I mean it's just like the sewing machine sound you mentioned but mine does get louder under acc. It's not louder than my engine/exhuaust noise, but you can hear them in the background. Maybe I'm just being paranoid, but I won't be at ease til after I check that lash thing. I put off from going to the track tonight, I'll wait till next week and be sure my car is fine. Thanks again. :thumb:

    I'll keep you updated on that lash thing. :comando:
     
  14. ryclef331

    ryclef331 Well-Known Member

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    If you can, take a quick video with hood open and at idle then host it somewhere (Streetfire, youtube, etc.). I can't probably tell you if it SHOULD soud like that.
     
  15. Nacho

    Nacho Active Member

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    I'll see if I can do this tonight.
     
  16. Nacho

    Nacho Active Member

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    haven't been able to get the video, but I did do that 0 lash check and the noise is still there. I guess I'm just going to dismiss it as normal mechanical rocker noise.

    Thanks for all your help! :drunk: