cockerstar Posted May 26, 2009 Share Posted May 26, 2009 So, my 240 sounds like a diesel, and I assumed I just needed to adjust my valves. Turns out that the PO (who rebuilt the engine and head) hadn't set the initial clearances and the adjustment and locking nuts were all at the bottom, great. So I set them to the cold specs (.008 intake and .010 exhaust) and the noise went away for about 10 seconds of idling and then returned. I rechecked them and set them to the same specs, but with a much tighter drag on the feeler gauges. Started it back up and it sounded better than ever. Nice and quiet like it should be, but after about 30 seconds of idling and 2 or 3 revs to about 2500rpms the noise came back. This isn't enough time for the engine to even come close to warming up, so I don't think I'm in range to be testing hot specs. I'm able to turn the adjusting nut even when the lock-nut is tight against it, and this strikes me as odd. Possibly the source of my issues? What would cause my valves to come out of adjustment so quickly? Right after they have been set tightly everything is great! This is the only thing keeping me from putting my car back on the road, and I honestly have no idea what is wrong. Any help is greatly appreciated Thanks in advance, Ryan Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 26, 2009 Administrators Share Posted May 26, 2009 Inspect the cam lobes very carefully for evidence of wear, i.e. ridges, lips, gouging, pits, etc. If the wiping pattern is incorrect at the proper valve lash adjustment, the cam could easily be destroying itself, hence going from quiet to noisy in short order... I'm hoping that is not the case here. Another aspect to consider is possible lack of cam oiling. Does the cam have the holes in the lobes for oiling, if not, is there a spray bar attached to the cam towers to feed oil to the cam-rocker interface? Now is oil coming out of those holes while the engine is running? 2 methods to verify this. 1) Starting the motor with the valve cover off to verify. You will know immediately and have wonderful slimy mess to clean up afterwards. Do NOT rev the engine as the cams will sling oil all over, but at idle, the slinging oil will be minimal. 2) Disconnect the coil and have a helper crank the engine over for a few seconds while you watch the cam lobes/spray bar for oil ooosing out of those holes. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted May 26, 2009 Author Share Posted May 26, 2009 It's an externally oiled cam, and I replaced the damaged spray bar with one from my parts car, so I'm sure hoping that my cam is getting the proper oiling! I'll verify asap. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted May 26, 2009 Author Share Posted May 26, 2009 I had to crank for about 7-8 seconds, but after that a good thick stream of oil flowed out of my spray bar. Some of the lobes are shinier than others, but I can feel any edges from wear with my finger or by lightly scraping over the surface of the lobe with a socket. Hopefully everything is good there. All I can cone up with is the adjustment screws backing out, but that seems really bizarre. Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 26, 2009 Share Posted May 26, 2009 Make sure the cam tower bolts are torqued to proper spec, could it be the studs pulling? I adjusted my valves today. I adjust them with the keeper springs on, thinking that they will hold the rocker arm closer to where it's going to run when the engine is in operation. Also, the symptoms sound like a broken valve spring, might check it... This is a clearance adjustment, the problem will be very basic, so don't overlook the simple stuff. Make the clearance measurement with the wrenches off of the stud/jam nut, the wrenches can push the pivot end of the rocker arm up if they are too thick, or if you don't support them properly. This would give a false measurement. If you are properly snugging those jam nuts up, they won't be backing out, at least in my 15 year experience with L series engines happy wrenching Quote Link to comment Share on other sites More sharing options...
cockerstar Posted May 27, 2009 Author Share Posted May 27, 2009 I honestly don't know if they are torqued to spec or not. I'm adjusting mine exactly as they will be running in the car. Is there a different way to do it? I thinned one of my 14mm wrenches quite significantly with a dremel just for adjusting my valves. It's actually quite handy having it fit on the adjustment nut without bumping into anything. After I snug the jam nuts up, should I be able to easily rotate the adjustment nut with a wrench? Quote Link to comment Share on other sites More sharing options...
dan5138 Posted May 27, 2009 Share Posted May 27, 2009 You shouldn't be able to turn the adjusting nut at all after the jamb nut is tightened up. Don't be afraid to get those jamb nuts nice and tight, just gotta hold the adjuster with a backup wrench. If they are super easy to turn even with the jamb nut tight I could see there being enough vibration to back them off. It doesn't take much slop and these engines sound pretty bad. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 27, 2009 Share Posted May 27, 2009 You said the PO rebuilt the engine and head. Are you sure the cam is stock? If it's not and he didn't check the wipe pattern and use the correct lash pads, it's going to sound like a diesel even when you have the lash set perfectly using feeler gauges. A long time ago I bought a head with a reground cam and that was the case. Took me a long time to figure it out given I didn't know what the term "wipe pattern" meant Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 27, 2009 Share Posted May 27, 2009 Are you locking the jam nut to the top of the pivot ball? Just for reference, you hold the 14mm wrench stationary and turn the 17mm wrench right, Aka clockwise, or pull towards the rear of the vehicle. when done the jam nut will be all the way down. When your done the pivot will be locked in place. To move it will require considerable force, i'll guestimate in excess of 70ft-lbs. In other words, it aint moving on it's own, or even the force of the pivoting action from the rocker arm. Valve adjustments on the L series is very easy. Once again, good luck. Quote Link to comment Share on other sites More sharing options...
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