2eighTZ4me Posted November 20, 2013 Share Posted November 20, 2013 Aftermarket turbo grind cam from Delta Cams. P90 mechanical head - original stock valves. All wipe patterns done correctly and well within spec. It just started happening. I can't specify when - but the motor only has about 1000 miles on it. Once the motor gets warm - the valve train sounds like a Singer sewing machine. I called Delta - they said you can take the valve lash down to .004/.006 on this particular cam. I went from a standard .008/.010 down to .006 / .008 and it made no difference whatsoever. Once it gets warm and you hit near 2000rpms - it ticks like a Timex. I don't know how it could happen - because the head was perfect for the first +/- 750 miles - but now it ticks annoyingly - yet the car still runs like a bat out of hell. I have to think that the problem might be something between the (Nissan factory) lash pads and the valve tip. I can't think of anything else that would cause a noise of this magnitude - nor can I think of any event that would have changed this clearance. I'm afraid to put it on the dyno in this condition....it didn't used to do this. Really don't want to rip the head off and send it back to the machine shop if there's something I could do myself without a head R&R. Unfortunately, most of the problems I post, noone has a solid answer for - so I guess I f*** things up in my own particular way, and it needs to go back to the machine shop for review and measurement. Perhaps they cut too much off the valve stem when doing the valve job?? The head is of unknown origin/mileage - so I don't know if previous valve jobs were done and if the prior machine shop(s) cut too much off the tips of the valve stems. I would have thought that my machinist (who's done these motors for over 25 years) would have caught it - but maybe not. That's the direction I'm leaning - but I'm very open to other causes, if anyone has experienced this before. I know what standard L6 valve clatter sounds like - and this is on a magnitude of 10x when the car is warm. When at idle - you can barely hear it, but anything over 1800rpm - it'll let you know 'something is wrong'..... Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted November 20, 2013 Share Posted November 20, 2013 Did Delta also resurface the rockers? Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 20, 2013 Author Share Posted November 20, 2013 Indeed they did...and everything measured out with the wipe patterns. The surfacing on the pads were great but just a few thousandths thinner - it varied a bit from pad to pad. Had to buy a bunch of different lash pads once all measurements were taken - but it was dialed in to the T - all wipes dead center. You know somethin' I dont ?? Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted November 20, 2013 Share Posted November 20, 2013 Sometimes they don't get the two wear surfaces parallel. I checked all 12 of mine with a piece of glass and a dial indicator and found two that were completely horrible. They sent me two rockers no questions asked. Luckily the two they sent me were good. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 20, 2013 Author Share Posted November 20, 2013 So then - it's basically a function of how much they have to take off in order to get rid of the normal 'divots' that take place with stock rockers rolling on a high-mileage stock cam. Factory tolerances could wear to one side or another and you gotta take it off to get it flat again. Makes sense...unless I'm missing something crucial... is that the theory of which you speak? And where the hell are you in Georgia, and why haven't I met you yet? How much power are you making with your current setup?? Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 20, 2013 Share Posted November 20, 2013 If the clatter is only there when the engine is warmed up, I might suspect an oil issue; what oil are you running? Warmed up, the valve stem should dominate the expansion race and your lash should close up some; making the engine quieter. Are your valve stems made of Bismuth alloy? (that'd do it!) Quote Link to comment Share on other sites More sharing options...
TimZ Posted November 20, 2013 Share Posted November 20, 2013 Are you absolutely sure it's the valvetrain? An exhaust leak at the manifold gasket can make a pretty similar ticking sound, and it's not hard to imagine it changing with engine temperature... Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted November 20, 2013 Share Posted November 20, 2013 I'm in morrow right now about to move to marietta. I made a video on how I checked the rockers. Look up my youtube channel. Skirkland1980. I'm guessing I make close to 400hp. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 20, 2013 Author Share Posted November 20, 2013 Xnke - running Rotella diesel 15/40 oil. They are stock valves - to my knowledge. TimZ - it's definitely not an exhaust leak. An exhaust leak gets louder under more load - this is definitely a metallic clatter that's the same volume regardless of load. Even at free revving. I think skirkland1980 may be on to something. I watched his YouTube video about reground rockers from Delta Cams and boy - some of those were nasty off. The thing that puzzles me is that it used to not do this....at all. Motor was quiet as Elmer Fudd hunting wabbits. I didn't take anything apart or change anything. I simply pulled the motor to fix a torn TC rod bracket and put it right back in - all in one piece. Pulling the rockers in the next day or so to check them and give the lash pads/valve tips a thorough inspection. I will probably re-check the wipe patterns as well while I'm in there..... I REALLY don't want to pull the head....uggh... Quote Link to comment Share on other sites More sharing options...
aarang Posted November 20, 2013 Share Posted November 20, 2013 I had to check and adjust my delta turbo cam probably a good 4-5 times in the first 1000 miles. Delta recommends checking the lash cold at the valve, not on the lobe like the stock Nissan cam. Mine is set at .005 int and .007 exh. I used to run the diesel oil, but have since switched to Valvoline VR1 10w 30. That made mine quieter as well. I have over 5000 miles on mine now, and I check the lash a few times a year and it is still spot on. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 21, 2013 Author Share Posted November 21, 2013 I have a hard time believing the metallurgy changed in the cam by grinding it (Mine was a stock 'Japan' factory cam - not the CWC) such that you would need to do more than 2 valve adjustments. First one cold, second one hot to ensure expansion values are accurate. I've adjusted these valves at least 10 times - hot and cold, and every time, they're still spot on. I don't get it. I hear the noise - and it 'sounds' like extremely loose valves - but I measure and find everything is spot on. I have to believe skirkland1980's theory holds water. If the surface of the rocker where it meets the cam isn't flat, (because) it's on a pivot ball...it can rock back and forth during the wipes - like a ship in the ocean (especially since the tip where it meets the lash pad might not be ground flat either...) That could vary clearance under motion. Especially motion that gets to a 'breaking point' .... like it does when it's warm and 1800+ rpm's.... I've got a set of uncut factory rockers that have very minimal wear on them. I'm going to put them in and run them through one temperature cycle to see if they make noise. Yeah - I know - used rockers on a cam that was broken in on different rockers....this'll be an experiment....I've got Clifton's old turbo cam that I'm planning on installing anyways prior to going to the dyno (once I get this noise figured out) Not like I'm putting them in there for the long haul. That'll rule out the rockers bottom line. If indeed the rockers are the issue, I will have to create Plan B.....I have a friend that has resurfaced several sets locally and they looked really nice. In his kitchen sink.....yeah - we live in the South! Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 24, 2013 Share Posted November 24, 2013 Skirkland is the only person I've heard of who had rockers ground wrong at Delta; so i doubt it's a common thing. I've had a LOT of rockers reground there and haven't had any issues at all. This clacking noise...pull the valve cover and oil the entire world. Watch your valve train. Wear goggles... Quote Link to comment Share on other sites More sharing options...
Leon Posted November 24, 2013 Share Posted November 24, 2013 Skirkland is the only person I've heard of who had rockers ground wrong at Delta; so i doubt it's a common thing. I've had a LOT of rockers reground there and haven't had any issues at all. This clacking noise...pull the valve cover and oil the entire world. Watch your valve train. Wear goggles... 6 of 12 of my reground Delta rockers were not ground parallel. What I doubt is that many people actually take the time to check them. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted November 24, 2013 Share Posted November 24, 2013 I had excessive valvetrain noise as well on my newly rebuilt engine. I solved the problem, it came from the rocker tip geometry in contact with lash pads. Here is the thread about it: http://forums.hybridz.org/topic/110671-newly-rebuilt-engine-with-loud-tapping-noise-even-at-idle/ (see page 4 for pictures) Quote Link to comment Share on other sites More sharing options...
z-ya Posted November 24, 2013 Share Posted November 24, 2013 Are you checking the lash at the cam lobe or the lash pad? Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 24, 2013 Author Share Posted November 24, 2013 Checking at the cam lobe. Guess I'd have to file the edges of my feeler gauges to fit in that "H" groove in the lash pad?? Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 24, 2013 Author Share Posted November 24, 2013 I've used the Delta regrinds in the past on several different motors with no audible issue whatsoever. Granted - they were stock cams with stock lash pads. Not sure if they laid off the quality control person due to Obamacare, but after watching skirkland1980's video of him measuring their flatness with a dial indicator - I'm pretty convinced he and the others have hit the nail on the head. Even with .005 clearance at the lobe - I can still wiggle the rocker back and forth - so something isn't laying flat. Rockers are out (and while I'm at it - I'm installing Clifton's old turbo cam) and will be sent off to be measured and surfaced. I just don't trust myself. I may give it a wag on an old set just to see what's involved. Quote Link to comment Share on other sites More sharing options...
madkaw Posted November 24, 2013 Share Posted November 24, 2013 Can't say where my rockers came from(MSA cam kit from Schneider), but my rockers wee as much as .014 difference in flatness between the two surfaces. It shows on the cam and the lash pads. I tightened up my tolerances a couple of thou and it eliminated almost all ticking. The engine didn't start out this way, it progressively got worse with break in. I guess that's why some vendors are putting out CNC rockers because of the inconsistency. I believe the ticking did get more audible when the engine warmed up. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted November 24, 2013 Author Share Posted November 24, 2013 madkaw - that's my scenario exactly. Have (8) new Nissan factory rockers on the way and my buddy is going to grind the last 4. Thanks for all your help guys. I really didn't want to pull that head! Quote Link to comment Share on other sites More sharing options...
madkaw Posted November 24, 2013 Share Posted November 24, 2013 I would check the new ones before installing also Quote Link to comment Share on other sites More sharing options...
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