Hey guys- I've done some searching here and around the net, but come up empty, so I'm hoping the collective wisdom of the HAMB will help me once again. I have a 63 Biscayne with a freshly built, hopped up 292 six in it. I had pulled a running, but injured stock 292 out of the car for the new motor. Got the new motor in, got it broken in, and ran 1500 miles of fun. Then, weird things happened when I had adjusted the valves. Let me walk through the process I followed there: Removed spark plugs, wires, and distributor cap just to make accessing things a bit easier. The distributor itself didn't get touched. Removed valve cover Brought each cylinder to TDC, based on firing order, tightened the rocker nuts until the lash was gone, then went one more turn. Put everything back together as it was before When I hit the starter, the engine cranked but wouldn't fire. I double checked some wiring connections. When I hit the starter again, I heard a loud "bang!" from the engine bay, but no start still. I checked spark with an inline tester, and it looked both erratic and weak and I could see a fine red powder underneath the rotor. Since the distributor was a carry over, I thought maybe I had killed something in the electronics (disti is an HEI), so ordered a new disti from Langdon's since that was cheaper than replacing all the parts and Langdon spin tests distributors before they go out. Got the new disti installed, hit the starter, and.....I'm still at a no start condition. Things I've checked: fuses (all good) Voltage regulator (good) Distributor orientation to ensure its not 180* out. The rotor is at terminal one and the timing marks line up on the balancer, so I think I got this in correctly and should be good. What else might be causing this situation?? Your thoughts are appreciated.
Yup, confirmed at 1-5-3-6-2-4 in clockwise order. They're all seated on the plugs and the cap terminals.
Zero lash plus one full turn is too tight. I bet your valves aren't closing, so no compression. Back them off to zero, plus 1/4-1/2 turn. Then see what happens. if you got it running that tight you'd probably burn some valves anyway.
Yes but is it correct in relation to where the rotor is pointing??? I had mine one cap tower off and went crazy chasing my no start for two days. Then found I 1 in the 5 hole and so on.
Yes, the rotor, distributor, and cap all line up. I will triple check this. Thanks! Posted using the Full Custom H.A.M.B. App!
I had seen everything from 1/4 turn through 1 full turn online. Sometimes it's good to have actual experience. I'll get a compression tester and, assuming that it reads zero compression, I'll redo the adjustment, backing off as you describe. Posted using the Full Custom H.A.M.B. App!
zero lash, then one turn ok for hydraulic lifters. Mechanical lifters, NO. Just set the feeler gauge and tighten down till snug, then tighten lock nut.
tdc, compression stroke - zero lash + 1/2 turn. Any more and you'll have problems. I haven't adjusted a hydraulic lifter with the engine running since I was 16. lol...and boy am I glad, too. What a mess.
^^^X2. You say hopped up 292. Meaning what. Aftermarket cam? My experiance with performance cams with more lift is that one full turn is too much. The point of the adjustment is to seat the pushrod in the plunger, and each cam reacts different. Best to do as stated above, back the adjustment of to zero plus 1/4, start the engine, and adjust each one running, back off till it clatters, tighten till its quiet, than turn in slow,till it starts to slow down, and back off to the nearest 1/4 turn. it gets messy, so pick up some rocker arm clips, or get an old valve cover, and cut the top off so you can get your socket on.
I dont go by TDC when adjusting valves. Turn engine until the pushrod is all the way up, mark the balancer and the timing tab with a chalk line, spin the crank 360 degress and line up the marks again. This will guarantee that the cam lobe is on the base circle. Tighten the lock nut while tapping the rocker up and down on the valve stem. When the tapping stops go 1/4 turn more for hydraulic lifters. Takes awhile for each valve but works 100 percent. For a running engine I adjust with the engine running, loosen the lock nut until it taps, tighten until no tapping, 1/4 turn more. Sounds like you definately went too far.
First off, do you KNOW FOR A FACT that you have hydraulic lifters? For the sake of argument I'm going to assume you do, but you need to know for sure. Hydraulic lifters require a certain pressure and volume of oil to work properly. In other words the engine has to be running and making oil pressure for the lifters to work. This is why it's usually recommended to make final lifter adjustments on a running engine at operating temperature. Doing a cold adjustment on a static engine is necessary to get things started. But it can be a little misleading if you don't know what really going on inside the lifter. You can twirl the pushrod between your fingers while slowly adjusting down the lash and you'll feel an increase in the drag of the pushrod as you try rotating it. "Zero lash" you think so you move on to the next valve and bump the motor over and move on to the next valve and so on and so on. But when you get all done and go back to check your work you'll find that at least a couple valves seem to have gone out of adjustment and the pushrods are loose and turn freely again. For now, trust your initial settings and fight the urge go back and make more adjustments. This is because hydraulic lifters bleed down to at least some small degree by design. This is how they are able to usually work silently under a wide range of temperatures and RPMs and compensate for wear in the camshaft and valvetrain. Used, old, worn or gunked up lifters may leak down even more, especially after the engine is shut off and oil pressure drops to zero. Yes, it can be messy. But you really should make your final adjustments on a warm, running engine. Slowly turn the adjustment down until the valve lash clatter just goes away on the valve you're working on. Then very slowly keep adjusting down an additional 1/4 to 1/2 a turn. As you're doing this the engine will likely develop a miss in that cylinder as the valve may not be fully seating. If the lifters are working as designed they should, after a few seconds, bleed down just enough to allow the valve to close fully and operate silently at zero lash. Assuming that the lifter isn't varnished up inside and your valve springs aren't terribly weak. The extra 1/4 or 1/2 turn of adjustment should be sufficient. A full turn probably isn't going to hurt anything but isn't necessary. Oh! For some real fun get a vacuum gauge and hook it up to a manifold vacuum source while doing your valve lash adjustments. Watch how much vacuum and how steady it reads while making your adjustments and how much it fluctuates when you have a valve that isn't fully seating. It's FUN and EDUCATIONAL!
One of the problems with "zero lash, plus one full turn" is each person's way of setting zero lash. If you turn the pushrod until it's snug, then you're way past zero lash. If you wiggle the rocker arm until it's snug, then you're way past zero. I've seen a lot of burned valves with zero, plus one turn, and a lot of different people thinking they started at zero when they did it. I personally have never had any valve train noise with zero, plus 1/4 turn on any engine I owned. Never saw a reason to go tighter than 1/4.
So it worked good before you fixed it? Why did you adjust the valves? Did you do the original valve adjustment when the motor was installed? As has been said, make sure you have hydraulic lifters. The high performance cam might have solid lifters.
Good points about the lifters - I know they're hydraulics because I bought and installed them. The adjustments were made because I was getting some tappet noise after break in - nothing huge though. It's entirely possible I went too far, and will be readjusting today. 1971BB427, those are good points about lash and differences in methods. I'll keep this in mind with the readjustment. drptop70ss, I'm using the "Exhaust opening, intake closing" method for setting the valves, as described by Leo Santucci in his Chevy Inline Power manual. I've used this same method before and had good results. Thanks all for the input - I'll update after I do the readjustment.
Thanks for the input from everyone. A compression check yesterday confirmed that I had royally screwed the valve adjustment. I backed everything way off, based on comments here and improving how I understood lash (which should be an ability to spin the pushrod, not stopping rocker arm movement), and the motor runs great.
Glad it's fixed! I just wanted to add a tech tip here: a piece of cardboard about 6" tall and the length of the head works well for retaining oil in a running engine. Even with high oil pressure the engine is not spinning fast enough to really sling it about, and the cardboard stops it from running out and down the side of the engine. Way easier than cutting a valve cover. Mike
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