383 240z Posted May 3, 2003 Share Posted May 3, 2003 I was driving my "other Hybrid" Yesterday and heard a loud clacking sound. I pulled it over and towed it home, pulled a valve cover and found a rocker arm with a blown out ball seat. The push rod looks ok but the othe rod on the same cyl. was broken. I'm guessing that the rocker broke and turned into the other rod and wedged it and it broke?? Sound feisable?? the rods are hardened with guide plates the rockers are stock 1.5:1 the cam is a Crane 113942 484"/.480" with a duration of 272*/284*. This is not a brand new motor I have been driving this car for about 250 miles after a head swap. Keith Quote Link to comment Share on other sites More sharing options...
denny411 Posted May 3, 2003 Share Posted May 3, 2003 If you didn`t properly lube the pivot ball with a moly based grease it could be lack of lubrication. Pull some of the others and check their condition. If nothing else, it`s a good excuse to buy a set of full roller rockers. Quote Link to comment Share on other sites More sharing options...
383 240z Posted May 3, 2003 Author Share Posted May 3, 2003 I'm betting that it was just a parts failure I lubed the hell out of everything when I installed the cam (I wiped a lobe once can't afford to do it again) I figure that if it lasted 200 miles it was just a parts failure. If it was an interference problem it would have failed very soon right?? Keith Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted May 5, 2003 Share Posted May 5, 2003 Do you have extended slots on your rockers? It could be your lift is high enough for the rocker slots to hit the studs. After a while they will crack and break there. Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 5, 2003 Share Posted May 5, 2003 If your looking for hipo then I'd get full roller rockers, or keep the RPM under 6200. Quote Link to comment Share on other sites More sharing options...
383 240z Posted May 6, 2003 Author Share Posted May 6, 2003 I did some searching in my garage and found a set of 1.6:1 rollers and a set of valve covers I mocked them up and there is no interference with the pushrod slot I hope this fixes my problem. Keith Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted May 6, 2003 Share Posted May 6, 2003 I did some searching in my garage and found a set of 1.6:1 rollers and a set of valve covers I mocked them up and there is no interference with the pushrod slot I hope this fixes my problem. Keith Make sure your valves don't hit the pistons with the 1.6 rollers. Quote Link to comment Share on other sites More sharing options...
383 240z Posted May 7, 2003 Author Share Posted May 7, 2003 I pulled a head and did that last night the piston is so far down in the bore and is a dished w/ 4 valve relief design I felt pretty good but I put play-do on the piston and cranked it over by hand I'm good to go!! Keith PS Mike did you get that book I sent you? Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted May 7, 2003 Share Posted May 7, 2003 PS Mike did you get that book I sent you? Yes I did! Thanks. I haven't had a chance to look at it yet. Let me know when you need it back. Mike Quote Link to comment Share on other sites More sharing options...
383 240z Posted May 7, 2003 Author Share Posted May 7, 2003 No hurry I just wanted to make sure you got it. I had sombody drop it of at the post office for me. Keith Quote Link to comment Share on other sites More sharing options...
Guest animated_life Posted May 30, 2005 Share Posted May 30, 2005 I just had the same thing happen with my engine. Is there any way, besides pulling the heads, that I can check to make sure my valves haven't hit my pistons? Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 30, 2005 Share Posted May 30, 2005 Other than what's been listed as causes, what about valve float? It can play havoc with OE type rockers. Check the spring pressure maybe? Quote Link to comment Share on other sites More sharing options...
Guest animated_life Posted May 31, 2005 Share Posted May 31, 2005 I just had another thought. I have vortec heads on my engine, but I'm not using the stock valve springs. I'm using 'double' valve springs that came with the heads when I bought them from a friend of my Dad. If I'm using the OE rocker arms and push rods, but I'm using these double valve springs, could that cause the push rod to push through the rocker arm like mine did? If so, do I have to go with some high end aluminum roller rockers instead of just using OE style replacement rockers? I'd really like to avoid having to pay for high end roller rockers if I can. With all the other work I need to do on this project, this is one part I'd like to stick with the OE replacement parts on. Thanks in advance for any help or insight. Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 31, 2005 Share Posted May 31, 2005 I'd look to see if you have enough retainer to valve guide clearance. If you have Vortec heads and they didn't have the guides shortened, the non-Vortec retainer or the lift of your cam could easily make the retainer hit the guide and cause a bind. But I'd think that would show up on more than just one rocker and maybe bend a pushrod or 8 as well. Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 31, 2005 Share Posted May 31, 2005 Either you have interference somewhere- piston to valve, retainer to guide, rocker slot to stud, spring coil bind; or the rockers just can't handle the spring pressure, causing the pushrod to punch thru the rocker. John Quote Link to comment Share on other sites More sharing options...
Guest animated_life Posted May 31, 2005 Share Posted May 31, 2005 Well I'm kind of at a loss right now then. Should I play it super safe and actually pull the heads, or should I just replace my rocker arms and push rods with OE replacement parts and move on? I'm hoping that maybe the problem lies with incorrect rocker nut adjustment and not any kind of interference. Would that make sense...or is it just wishful thinking? Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 31, 2005 Share Posted May 31, 2005 Don't just throw more parts at it. Find what caused the problem and correct it. First step would be a compression test or even better a leak down test. This will tell if you have bent any valves. If you do a compression test, look for 125 or so on all cylinders and uniform results. If you do a leak down, if it's leaking a good bit, listen to the intake and exhaust and see if you can hear any air escaping. If the cylinders that had the rocker problems have low compression or are blowing air, then the heads will have to come off and the valves repaired. Then put a set of light checking springs on one cyl and, one at a time, bring both valves to max lift. You can push down on the retainer and see if you have retainer/guide interference, and see if the slot in the rocker is free. You should have at least 0.100 free travel in both cases. This is a good time to check and make sure the pushrod isn't touching the head also. Bring the motor to 20 deg BTDC on the exhaust stroke. Push down on the valves and see how much clearance till the valve touches the piston. It's best to set up a dial indicator on the retainer so you know exactly how much, but you need at least 0.100, which is slightly less than 1/8" if you're on the cheap. Rotate the motor ahead about 5 deg and check each 5 deg till you get to 30 ATDC. The valves aren't closest at TDC, usually it's 10 - 20 degress ATDC when they are closest. If all this checks out, put the springs back on, bring the valve to max lift, and check for coil bind. You should be able to stick a 15-20 thou feeler guage between the coils at max lift. This is sorta a quick and dirty method; This is best done on a stand with a degree wheel and dial indicator, but you may not have that option. Vizard's book on setting up SBC valvetrains is excellent reading and much more in depth than what I've said here. Edit: If all this checks out OK, it's possible that the spring pressures are more than the rockers can handle, or the rockers may just be wore out. Valve springs should match you cam for seat pressure and pressure at max lift. John Quote Link to comment Share on other sites More sharing options...
Guest animated_life Posted May 31, 2005 Share Posted May 31, 2005 So get this, I just got back from the parts store and I've got odd news. I took in the two broken rocker arms and the push rods that are lodged in them and let the parts guys look at them. It turns out that the rods that I am currently using are the correct length for a Chevy 6 cylinder engine. I have no idea how those rods got in there, but they're too SHORT. The correct length push rods are almost 1/2" longer than the ones that are currently in my engine. If all of this is true, then to use the incorrect (shorter) push rods, I would have had to tighten down the rocker arm nuts much further down the stud than they really should be, which would change the geometry and possibly put a lot more stress on them. Maybe this is why I broke a couple rocker arms. This is my wishful thinking theory as of right now. Why I trusted the rods that my Dad gave me with the heads when I bought them from one of his friends is beyond me. I should have checked them and made sure before installing them. Can you tell that this is my first SBC rebuild project? Anyhow, I hope that this theory stands up and I have definitely learned from this whole experience. Quote Link to comment Share on other sites More sharing options...
jt1 Posted May 31, 2005 Share Posted May 31, 2005 Are there any blue places on the rocker balls? The oil hole might not have been lining up enough to oil the balls. Anyway, hope that fixes it. John Quote Link to comment Share on other sites More sharing options...
Guest animated_life Posted May 31, 2005 Share Posted May 31, 2005 Nope, no blue places on the rocker balls. Quote Link to comment Share on other sites More sharing options...
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