Did I flatten one? Went to adjust the valves tonight on my solid cam and found one of the lashes VERY loose, over .50. Loosened the lock nut and started to adjust it down. Well, I screwed the poly lock all the way to the stop and I could still lift the pushrod with my fingers! The exhaust valve on this cylinder was just starting to open so I should have been on the base cicle for the intake I was adjusting. Am I missing something (other than perhaps a lobe!)
Assuming that the pushrod is straight (I am sure if it was bent that badly you would have noticed), I would pull the rocker off and check that the pushrod moves up an amount = to the intake lobe lift stated on the cam card. If not, it is very likely a lobe and/or lifter problem.
Possable but could also be a lifter or the poly-lok itself. Had one that the set screw jammed and would not allow the nut to go down anymore. Try taking the set screw out and see if the nut will go down to take up the lash. Do you have screw in studs? Doe's the pushrod move at all when turning the engine by hand?
Dave, the jam nut is removed and I cranked the poly all the way down. As I turn over the motor the arm does travel up and down. Without a dial gauge it is hard to tell how much though. What is starnge is strange is that when the poly is tightened down all the way I can still move the pushrod up and dwn by at leage 1/4"
One trick to measure is to get the lifter on the base circle and scribe a line on the pushrod that references a fixed part of the cylinder head (like the valve cover rail). Rotate the motor until the lifter is at its highest point and scribe a line at the same reference point. Measuring the distance between the two lines will give you the lobe lift. 1/4" to 3/8" less than the others is a lot. I don't know what camshaft you have but most have less than .400" of lobe lift. Subtracting .25 or .375 probably leaves you with little or no lobe lift.
Here is my cam. The cam is a crane #363841 solid lifter int .553 exh .555 dur is .284/.294 .238/.248 @.050. I will try the scribing idea, better than what I just tried. I also just noticed that the bottom of that particular rocker arm has slight grooves cut into the bottom from rubbing on the screw in stud. Sounds like I killed a lobe!
With a 1.6 rocker ratio, your lobe lift ~ .346". You should measure something close to that using the method in my other post (it's not a perfect method but should be a reasonably accurate measurement). If your measurement is significantly less than .346", you definitely have a lifter/lobe problem.
Checked it, it is less :-( What could be wrong with a solid lifter? I a assuming it is the lobe causing the lack of lift.
Wow. That's a lot (1/4"-3/8" less lift). Granted, I don't know a lot about solid cams, but I can't imagine the relatively soft lifter flattening out nearly 3/16" face in the harder cam. My guess is a bad lifter (assuming they're hydraulic and not solid). Edit: we were posting at the same time. I'll ask anyway, are you sure it's not a hydraulic lifter?
Hmm.... Bad spring maybe? (I'm trying desperately for YOU to find a different culprit than a flattened lobe - but.... )
Usually both the lifter and the lobe are ruined when a lobe wipes out. The lifter quits spinning and the lobe just wears through the bottom of lifter. How far off is the measurement? If it's .010-.020", that could be problem wih the measurement. I would pull the intake and lifter to investigate if the difference is much more than that.
The other pushrod on the same cylinder comes almost to the top of the stud whil the suspect rod is significantly lower. I will pull the intake tommrw. Thanks Rick, I too was looking for something smaller than a new cam! First car show after all this work is in a week and a half. I feel some thrashing going on!
