Adjusting Lt4 roller rockers
Adjusting Lt4 roller rockers See pics, pulled vc off at 300 miles of run time. It developed a slight ticking under the passenger side vc in the last 50 miles reving the new 215/224 .533 cam to 5500rpm. All the poly locks were still tight. Im thinking it just needs a fresh zero lash and a 3/4 turn past zero lash to quite it back down? Doesnt sound like a lifter, its just that high pitch ticking. How are my witness marks looking on the valve stems??? Anything else i should be looking for? Thanks.
P.S. car pulled like a freight train with new 215/224 cam, headers, magnaflow catback, ewp, and Solomon tune. Feels like a high 12, low 13 sec car now.
P.S. car pulled like a freight train with new 215/224 cam, headers, magnaflow catback, ewp, and Solomon tune. Feels like a high 12, low 13 sec car now.
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Joined: Jun 2002
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From: Houston
put a stethoscope on each rocker arm stud or trunion and you'll know quick which valve is tapping. While the motor is running, loosen the locks and tighten down the rocker until the noise goes away. If you have to tighten more than half a turn (assuming that at one point in the past the valve was quiet), then there is a good chance something else is the issue. Valves rarely start tapping over time if the lash was done right from the start and all of the locks are tight. You might have a different issue such as a flat lobed cam, faulty lifter, or bent pushrod..
Thanks for the advice. Cam is billet steel so dont say wiped lobe lol! Pushrods are hardened. I will check the pushrods though just in case. It may just be a header gasket starting to leak.it was a high pitch tick up high def not a deep tapping. I do have a stethoscope to use.
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Joined: Apr 2008
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looking at the second pic....it may be reflection but the keepers appear to have witness mark on them from SA rocker tabs on each side of the valve tip. I expanded pic which did make it less resolution but both the cyl without RR on it "looks" like there may be contact from the SA tabs on keepers (locks)
you have a closer view than we do. Also look closely at the RR tabs for any sign they are bottoming out.
If this is the case you need to switch to NSA & guide plates
you have a closer view than we do. Also look closely at the RR tabs for any sign they are bottoming out.
If this is the case you need to switch to NSA & guide plates
Thanks i will check, but yah it looks like they are just barely knicking the retainers, those are 611 locks and are supp to work perfect with gm rr's. Is the wear on the rocker studs and pushrods pretty normal looking?
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Joined: Apr 2008
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the witness mark on valve is ok...slightly wide. If you have a adjustable PR check tool you could try a .050 shorter to see if the sweep mark narrows (good) but if not dead nuts center you want it favoring the exhaust side vs intake of motor as yours does. Either way the PR length shouldn't cause the tick sound you hear as your PR length is not off if any at all. Was just suggesting check it with a .050 shorter to see if it gets better.
I used my Crane SA's with 10309 Crane springs without issue. With Comp 987 springs there was "slight" contact as I found some small witness marks on retainers
IMHO motors that spin higher than 5700 rpm should run NSA & guide plates. I know people spin the crap out of SA RR...but I had one jump off a valve so went NSA
I used my Crane SA's with 10309 Crane springs without issue. With Comp 987 springs there was "slight" contact as I found some small witness marks on retainers
IMHO motors that spin higher than 5700 rpm should run NSA & guide plates. I know people spin the crap out of SA RR...but I had one jump off a valve so went NSA
Thanks for the advice! Lloyd also said that a 7.050 would be better on the valve guide life. Prob order them up! Trick flow 5/16, .080 thick walls, chromemoly. My current cam peeks at 5800rpm. I revved it to about 5400 yesterday. Awesome mid range power with his 215/224 cam. And i can still lug 6th gear uphill at 1500rpm if needed, great all around cam. I have lower control arms, relo brackets, panhard bar, bilstein shocks and semi sticky tires. Had good traction with stock power. Now i lay 100ft black marks in 2nd gear. Car stays straight though. Thought it was hooking until i looked in the rear view mirror and seen the black marks lol.
Next build "383" def going with guide plates and nsa rr's.
Next build "383" def going with guide plates and nsa rr's.
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Joined: Apr 2008
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At 5400 rpm the SA's are fine. What you need to rule out is if the SA tabs/washers are hitting the retainers or locks. 10 degree locks & retainers may help get more valve stem "up". If not you don't want to continue with the SA's "IF" there is contact of the SA part of them
Not saying you do...just from the pics it looks like small marks L&R of the valve stem on the keepers...or its just reflection
you see better than we do from this side of the internet
FWIW I chased a "tick" I felt was valve train so checked....multiple times and re-lash. It turned out to be a pin hole on one of the DS header primary's....so in your case it could be exhaust leak but from the pics...check out that there is no RR to valve retainer/keeper contact
Not saying you do...just from the pics it looks like small marks L&R of the valve stem on the keepers...or its just reflection
you see better than we do from this side of the internet
FWIW I chased a "tick" I felt was valve train so checked....multiple times and re-lash. It turned out to be a pin hole on one of the DS header primary's....so in your case it could be exhaust leak but from the pics...check out that there is no RR to valve retainer/keeper contact
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Verdad Gallardo The 7.050 pushrods might help the valvetrain geometry too, help keep the rr's centered on the rocker stud and not too far forward towards the valvestem/retainer. Im ordering them and will give it a try. And i will keep an eye on retainer interference. And watch out for that famous sneaky header leak!
Checked the bottom of the roller rocker tabs and no signs of striking the retainers. Good news there. Looks like i have some roller rockers moving around on the valve stems of the #4 and #6 cylinder. Zoom in on this pic! I went ahead and bought the .050 shorter pushrods. Springs look good.