Hey guys, doin some brainstorming before I get into the motor. Stock rebuild on a 71 LS-5. Everything has been done including setting the spring heights with the new matching valve springs. Heres what I got. Mild Lunati hyd cam/lifters/springs & timing chain. Comp cam roller rockers and pushrods. Used Royal Purple break in oil along with Gm eos. Obviously adj valves before starting and then adj valves after the motor warmed up. No problems fired right up, no overheating, oil pressure 35-40 at idle. Changed oil/filter and added red line oil additive. After 1st drive heard ticking and it was #8 intake, readjusted valve while it was running and it really didn't like to be adjusted. Didn't want to stay running, couldn't turn it more that 1/8 turn at a time. By the way it wasn't that way the 1st time it was adjusted. Long story short, it's been adjusted 3 times more and always same one (there was popping in the exhaust one time). A buddy told me that it's possible (not likely) that it could be the lifter since it didn't respond well to the adjusting. He said to pull the intake and look at the lifter before anything else. If it has wear than you know it's the cam, if not it's probably the lifter. Does that make sense to anyone? Obviously thats the 1st place I'm going, but what are the chances of a bad lifter?
Dave

 

the chances of it being a lifter are slim to none. if you know how to adjust the valves on a hydralic cam, assuming this was done correctly, and you have screw in studs and locking adjusters on your rockers, then the cam is trash most likely.

I'd advise checking your settings and if it continues to loosen, you can always do a rough check on the valve lift turning the engine over and comparing to the next valve over.

this is advise for a flat tappet hydralic, not roller

 

Hopefully you ran the motor right up to 2500 RPM for at least 20 mins or per whatever your cam builder recommended - before you adjusted the valves as you wrote "Obviously adj valves before starting and then adj valves after the motor warmed up." Or did you adjust them during that initial run up while it was spinning so fast? If so, I'll bet that sent some oil around the engine compartment!

I just did the top end on mine and I made sure I set the valves 1/2 turn past zero lash (using #1 and full crank rotate for the #6 companion cylinder method) per Comp Cams instructions. I ran it from start up right up to 2500 and let it run like that for 25 mins - while monitoring for water temp and any oil leaks. Even though I used their good cam lube and assembly lube I am still hoping that the cam survived as so many folks report issues based on the low-ZDDC oil sold today - see the sticky for oil at the top of this section. With maybe 200 miles on it since the overhaul, I have a slight tapping not heard at idle but audible out on the highway at speed when driving near a crash barrier (left lane passing, etc...) but suspect it to be a bad fuel pump. The motor idles a bit rough - is my XE262H, a 218/224 110 LSA cam wild enough to induce this? At 750 RPM it is slightly rough but it clears right up past 900 RPM and makes plenty of power - no backfiring or spitting, etc... I will adjust valves again with it running and check it out this weekend.

 

pull the filter and look for metal !

not to be a stick in the mud but I had 2 Crane cams go bad back to back ....we did everything right ...they missed Heat Treatments @ Crane....they sent me a Hyd. Roller and lifters for all my troubles ( I let them know exactly how I felt about tearing my engine down TWICE & repalceing all bearings. )

since then I will never go back to a flat tappet cam ...Good Luck !

 

Valves were adjusted after the break in and oil change. 1/2 turn from zero. I really am thinking of a roller now.

 

Ok - both of you are scaring the crap out of me as well...

 

Just pull the valve cover and see if the valve is opening. There is definitely a chance that you just have a bad lifter.
The first sign of a cam going flat is usually not a tapping sound from the rockers. The engine usually just develops a miss.
I have seen cams go flat that never had any valve train noise at all. This is because you will have significant wear on the nose of the lobe, but not very much on the base circle, which is where your preload is set.

 

As for my car - the roughness only at 750 RPM idle makes the motor shake just a bit - some might think it had an occasional miss at idle, or this could be normal function for a cam slightly more aggressive than the 206-210 basic factory stuff... So would that miss show at all RPM's or could it be felt just or mostly at idle? In other words, if the car runs fine past 900 RPM and makes lots of solid power as it winds up - evidencing no miss at all while doing so, am I to be encouraged that the cam is OK before I can get valve covers off tomorrow and check for wear and adjust lifters? I have not done that since breaking in the new cam. I ask this because even when they are worn out (like my top end was before I did all this work) our big blocks seem to be able to hide alot of problems and just keep on running - all that torque!

 

the ticking you hear may also be a slight exhaust leak too ?

 

When the cam first starts to lose a lobe, you could possibly feel a miss only at idle. As the rpm increase a weak cylinder is much less noticable.
Still, a cam isnt the first thing I think of if an engine doesnt have a glass smooth idle.
Any tapping you hear is possibly just from running one of Comps XE cams. They are known to be fairly noisy profiles.

 

I had 2 lifters that ticked from day of a crane cam and lifter kit. Adjusted 5 times and still the same tick. I installed a lunati wth crower camsaver lifters and so far nice and quiet but I only have about 75 miles on it so far. I'm counting on the camsaver lifters tp help protect the cam. I now have valvoline VR 1 10w 30 and a bottle of EOS in it(first oil after break in).

 

we used to throw in a cam and lifter kit brake it in and go racing never had any trouble,now all u hear about is trouble.we switched to roller cams along timeago have never had issues.it has got to be these new oils

 

He has a Lunati Cam kit. Check lift at the #8 exhaust valve and compare to another exhaut valve. Cut open filter and check for shavings. There is no way I would run a flat tappet cam anymore. This has been discussed at length but I belive the increased Hydraulic intensities on todays lobe designs and the oil composition both are contributing to the increase of wiped lobes.

 

The OP has a Lunati cam.
I was responding to djcwardog. He has an XE262h.

 

right!

 

My Comp XE250H cam in my SBC is a long way from the luanti cam in the BBC, that is in the OPs motor. He has not given specs, but his springs my be pretty stiff. Anyway, I have always adjusted Hyd. lifters on the engine stand, with plenty of assembly lube.I put the valve covers on. And never had to touch them again. I`ve always primed the oil pump, fill the carb with fuel, set the timing @ somewere around TDC. And the engines come to life in a rev of 2, run them up to 2500 immediatly for 30 min. and never had a problem. I have used this procedure since in high school, that was 32 years ago. Its got to be the oils of today, unless the cams missed a heat treat process as mentioned above. I run Shell Rotella T oil with Lucas oil stabilizer. 4000 miles since cam was put in no problems, no noise. Just my thoughts.