gprimm Posted June 1, 2012 Share Posted June 1, 2012 I am adjusting the valves on my SBC. I tighten them 1/2 turn past preload. Have done this before several times and everything was fine. Tonight as I was doing this, for instance on #1 when you do both the intake and exhaust,I would go back (just a few minutes after final adjustment)and check and they would have "loosened" up a bit. That is, being able to turn the pushrod; whereas after I had just "Loaded" it, it would not turn. What's going on? When I adjusted before, I would never go back and check. Kinda strange. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted June 1, 2012 Share Posted June 1, 2012 I assume your doing this with the engine not running. New lifters? new cam? flat tappet or roller? Hydaulic I assume did you fill the lifters with oil? (new lifters) Its been a while for me too but may be doing it this winter with cam and lifter change. Quote Link to comment Share on other sites More sharing options...
gprimm Posted June 1, 2012 Author Share Posted June 1, 2012 Just changed the rocker arms from standard to full roller. I had roller tip rockers on there and the same happened. Quote Link to comment Share on other sites More sharing options...
FASTSS454 Posted June 1, 2012 Share Posted June 1, 2012 I prefer to adjust them while engine is running, call me old school but that was the way I learned how to do it when our cars were new. Quote Link to comment Share on other sites More sharing options...
wallaby Posted June 1, 2012 Share Posted June 1, 2012 I guess I'm old school too then. I always do the final adjustment with the engine running. I guess I don't trust 'em till I've seen them in action. lol Quote Link to comment Share on other sites More sharing options...
overdrive Posted June 1, 2012 Share Posted June 1, 2012 Different lifters require different preload settings. I just installed some Comp rollers that they recommend setting at 1 to 1 1/2 turns past 0 lash, but many other lifters , including many made by Comp, need less preload. Make sure of what's recommended for your specific lifter part #, if they are aftermarket. Your pushrods probably just have a little less pressure on them because a little of the oil in the lifter has bled off after the valve spring has had some time to push against the lifter plunger. The lifters will pump up again as soon as they get oil pressure. I've used both the engine running or not running methods to adjust valves and I like the less mess way the best. Just make sure you are careful when locating the 0 lash point. It's easy to set the preload too high if you only rely on spinning the pushrod while tightening the rocker nut to find 0 lash. If the lifter doesn't have much oil in it, the plunger can be pushed down some (preloaded a little) before you feel much resistance to spinning of the pushrod. 0 lash is when the lifter plunger is all the way up and the pushrod can't be moved up or down. Dan Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted June 1, 2012 Share Posted June 1, 2012 When they appear to collapse minutes after adjustment it is the lifter bleeding down as the plunger releases pressure. Perfectly normal. Now, if you notice a smelly discharge when you........yeah, nevermind. Quote Link to comment Share on other sites More sharing options...
gprimm Posted June 2, 2012 Author Share Posted June 2, 2012 Andy's Auto: thanks. Was kinda thinking that. What is your preferred adjustment: 1/2 , 3/4 or 1 full turn as the final adjustment? I have done 1 full turn in the past on stock stamped rockers. Have Procomp rollers and was doing 1/2 turn. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted June 2, 2012 Share Posted June 2, 2012 check what the lifter maker requires a half turn is pretty close to .030 Quote Link to comment Share on other sites More sharing options...
Andy's Auto Posted June 2, 2012 Share Posted June 2, 2012 Andy's Auto: thanks. Was kinda thinking that. What is your preferred adjustment: 1/2 , 3/4 or 1 full turn as the final adjustment? I have done 1 full turn in the past on stock stamped rockers. Have Procomp rollers and was doing 1/2 turn. Stock stuff I always hit with 1/2 turn. Morels and Bullits rollers need a full turn. Lunati, Crower, and Crane are all over the place depending on application. The biggest thing past noise is that if you get a rocker too tight, you have a change that after a good beat down, the valecan hang open for a few minutes and you could lose that cylinder. Then the is piston to valve clearance issues on high compression motors or mismatched pistons and heads. Quote Link to comment Share on other sites More sharing options...
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