Valve clatter could it be timing?

Discussion in 'Classic Mustang Specific Tech' started by jeffnoel, Sep 14, 2007.

  1. i can never get mine to stop chattering. at idle its fine but when you take it on the road it gets rough. i actually got some pretty thick valve covers and you can still hear them.
  2. OK, haven't made time to get any 91 yet but what I have done is sat in the car and watched the tach as I press the peddle. So far I have just been revving the but not slowing raising the RPM and holding it to see if there was a rough spot in the RPM range.

    It revs smoothly to 1500 then it starts to miss and stumble and by 2000 it's pretty rough. Now granted this is the first time I checked this way and haven't verified that it does it at this RPM every time. Maybe it's time to replace my timing light, I'll get/borrow another and check mine against it. Does it still sound like a timing issue or more of a carb issue. Maybe I can get a friend to help and move the dist while at the higher RPM to see if the stumble goes away. I have attached a video so you can see/hear what I'm talking about.


    Attached Files:

  3. Your cam has the same specs as mine except I'm using the 1.7 RRs for more lift. And like you I'm running thicker aluminum VCs and still hear the clatter, are you just living with it?

    The sound, as best as I can describe is similar to that of my 1st car a 69 Fairlane with 351W/FMX combo. That thing was gear'd for the Autobahn 2.63s in the rear, and when climbing a steep grade if you tried to give it to much gas the valves would start to rattle until you let off the gas a little, but that's the only time that car would do it. Funny thing is I ran a cam in the 351 that had the same specs as what I'm running in my 302 know.
  4. With all that noise, there's no way you're going to hear pinging or detonation. If you're hearing what you describe as valve noise, it's coming from the valvetrain, not inside the cylinders. Rough like it sounds, I'd say you've got the rockers set too tight. Rough running with no valvetrain noise would be an ignition or fuel problem(other than lack of octane to control pinging) Be that as it may, I'd still advise you to refill the tank with premium just to be safe. Once you've got it road worthy, then you'll be able to take it out and tell if you do have pinging problems, you'll need to drive it with the windows up to hear it.
  5. Could this be an issue of the highway gears (3.00:1) and this cam?
  6. pretty sure gears are not going to aid in this, unless they are really high (low number) and ithas not downshifted.

    and yes i am living with it for now.
  7. The more I think about it, I think you're valve lash is too tight.

    And I've never seen anybody break one of those pedistals.
  8. That's what I ment.

    I've had best luck with pedistal style rockers preloaded 1/2 to 1/4 turn. Any more than that causes the lifters to pump up prematurely and in my car made my valve train nosier than usual.

    I have those same roller rockers and I can tell you mine are fairly loud even underneath the pot metal valve covers.
  9. I don't have sound so i can't tell. You have roller rockers...those can hit some types of VC on the underside also. In the baffle area.
    For rocker geometry just take one off and look at the wear pattern if the stems were new before. If not, paint the top of one or two and re-adjust them and turn the motor over. Remove, and you should see a wear pattern in the center.
  10. If the rockers were contacting the VCs the would do it all the time not just under load. Besides I've got tall VCs with no baffles so I guarentee the rockers aren't hittin them.

    OK, got a few minutes of help from a bud today. Had him on the gas watching the tach while I watched the timing light/marks. Had him rev it slowly to 3K rpm and hold. Timing at idle is 12 at 3 grand it peaked at 29. I davanced it so total timing was more like 32 and he said it felt like it took more peddle to get there and it didn't do it quit as smoothly. While I was watching the timing marks it didn't seem to advance real fluidly, it seemed move a couple degrees as rpm increased and then it would move a couple more degrees sort of like climbing steps not linear like I expected. Know I'm not saying it bounced around like I have play in the distributor shaft or something the timing stayed steady at rpm it just did advance like I expected.

    So could the problem be with the curve in the smog era Duraspark distributor I'm running. I'm also wondering about the timing marks on the Professional Products damper I got, I need to get a TDC finder and verify the timing marks on the balancer.

    Also D.Hearne I added 5 gal of 91 to the tank and ran it for a little to blend in the tank and make sure it gets to the fuel bowls but haven't tested the octane theory yet on the road.

    And I'd like to THANK each and everyone of you that have chimed in!!!! Please keep it up and hep a brutha out.
  11. Could my vacuum advance be giving to much advance?
  12. trust me, with all the noise your motor is putting out, sitting there and reving it, there's no way in hades, you're going to hear detonation, pinging, or what not coming from inside the cylinders. You'll HAVE to drive the car, with the windows up to block out the exhaust noise to ever be able to hear sounds from inside the cylinders. If you are hearing something, it's coming from the rockers.
  13. Man that's harsh D.Hearne what your calling noise I call Music to my ears, lol. But I know your right and just haven't made the time to do that.

  14. are you saying that proper torque (20 ft-lbs) was had after roughly 1/2 turn of "preload"? I'm thinking the geometry is off somehow....only way to correct that would be with different length pushrods or shims.
  15. Also, according to your earlier post your plugs are gapped to .060". That is way to much gap. Close them down to .035 - .040". Your ignition is going to have trouble making good spark with that gap. I'm not surprised that is has trouble firing as RPMs climb. Try this and and see if it helps.

  16. Yes, I am following the directions from Crane on setting the preload and I'm torqueing on the low side of the recomended 18-20 ft lbs achieved betweeon 1/4 and 1/2 turn. If it was a valvetrain setup issue wouldn't it make the noise all the time not just when under load?

    Plug gap per all the books I have and the sticker on my factory VC say 0.060" plug gap.
  17. And with an MSD you can gap them even bigger.
  18. 0.060" is the largest gap recommended by MSD. They recommend 0.050" - 0.060" for up to 10.5:1 compression. I use a different capacitive discharge box, but similar. My gaps were at .050". When I took it to be dyno'd, the top tuner there told me to take them down to 0.040". I only had a few hundred miles on the motor and the plugs were already shot. I'm only running 10:1 compression. I'd take then down and see what it does.
  19. I don't know if this is useful for OP, but I got something out of it.

    Where did you dyno your car?