Valve train clack - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 18 (permalink) Old Jun 18th, 02, 11:52 AM Thread Starter
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Join Date: May 2001
Location: Austin TX USA
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I've had good luck with engines lately but on a recently rebuilt 406 sb, I can't seem to eliminate valve train noise. It's pretty loud...not a tick. I've adjusted the rockers both cold and hot, which eliminates the noise temporarily (5 or 10 minutes) but the noise returns. It's not one rocker/lifter,..it sounds like two or three or more.

The engine/valve train:

406 sb
9.4 compression
AFR 195's, 74 cc (new heads)
AFR guideplates
AFR valve springs; 120# at the seat, 310 open
Magnum 280H cam, 230 @ 50, .480/480 lift
Comp hydraulic lifters
Comp hardened 5/16 push rods
Comp roller tip rockers
Comp poly locks

Other notes:

The initial break-in...the engine fired up at the touch of the key. I followed Comp's break-in instructions perfectly with two exceptions. I didn't remove the 'inner' valve spring. I was told by two respected engine builders that this was unnecessary with my mild spring pressure (stated above). Secondly, 10 minutes into the break-in I shut the engine down because she was approaching 230 degrees. I waited 30 minutes, and resumed break-in...2000-2500 rpm for another 10-12 minutes. Water temp stayed around 210 on the second go-around.

I did use the Comp lifter break-in lube,..the little packets, though I didn't think much of it...it seemed slightly more viscous than 80 wt oil...in other words, I'm sure most of it drips away. The cam was lubed with a better-looking assy lube...the gray pasty-looking stuff. The short-block was built by a machine shop,..I did the top half of the engine and install into the 69.

The chatter started about 5 minutes into the initial break-in and at the time I didn't think it much of a big deal.

I did see weird fluctuations in oil pressure during break-in...both high and low...15-70 PSI, but I reasoned that the break-in/assembly lube(s) were causing this. Pressure is steady and strong now after an oil change.

But I can't seem to eliminate the clicking...also, the engine runs poorly. I've built this exact (almost) combo before and I know it should have twice the power she's giving me now.

I've ruled out the follwing:

1) Guide plate misalignment...they're fine...rocker tips are nicely centered over the valve stems.
2) Oil not reaching the valve train...it is.
3) Bent push rods...I checked a couple
4) Poor rocker to valve stem geometry..it's good
5) Poly locks coming loose...they're good and tight.
6) Header leak (this has fooled me before)
7) Loose rocker studs...all 16 are torqued to specs with red-loctite.

My most recent adjustment, I cold adjusted by bringing each piston to TDC (following compression stroke), feeling for zero lash, then a 1/2 turn on both rockers. In other words, the valves were adjusted with the lifters on the base circle.

But, the chatter returned before I pulled out of the driveway.

The chump is stumped, but thinking the worst...a lobe or two has been scrubbed off.

Any other ideas before I jerk the engine?

Thanks in advance!..and sorry ofr the long post.
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post #2 of 18 (permalink) Old Jun 18th, 02, 01:59 PM
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Location: longmont, colorado
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Check one of the ticking valves for total lift. (Measure lift using a dial indicator on the pushrod tip)I hate to say it but it sounds like some wiped out lobes.You can usually adjust the clack away for a short time, then it wears more material off quickly and resumes clacking.
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post #3 of 18 (permalink) Old Jun 18th, 02, 05:22 PM
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gotta agree with sunoco special youve lost lobes but one more thing did you use the correct oil pump rod an non plastic retainer for the rod. there not the same for a 400 as a 350 an if the reatainer snapped can be noisy but i think your buying a cam. ps lucas works great for cam break in but use a paste on the cam.
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post #4 of 18 (permalink) Old Jun 19th, 02, 04:37 AM Thread Starter
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I agree with your diagnosis...I don't know what else to look for.

I'm now resigned to pulling the engine and doing an autopsy unless others have any ideas.

How did this happen??? How did I wipe out cam lobes?
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post #5 of 18 (permalink) Old Jun 19th, 02, 04:54 AM
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<BLOCKQUOTE>quote:</font><HR>Originally posted by Sleepy-69:

I followed Comp's break-in instructions perfectly with two exceptions. [/B]<HR></BLOCKQUOTE>

AL.


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'69 Z28 (X77 D80 72 72)
302, GM Crossram, Steel Crossram Hood, Doug Nash 5 speed, 3.42's
Body Engine1 UnderHood
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post #6 of 18 (permalink) Old Jun 19th, 02, 07:06 AM
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It should be relatively easy to determine which set of valve train components are making the noise. I know that my brother has had problems with the Comp Cams lifters on more than one occasion. Problems have been with the regular hydraulic tappets as well as the hydraulic rollers. No problems with the cams in either case. Comp replaced the units
in each case.
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post #7 of 18 (permalink) Old Jun 19th, 02, 10:01 AM
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I have heard there are a lot more troubles with modern flat tappet cams because of Federally mandated EPA restrictions. Apparently cam manufacturers don't harden camshafts and lifters as well because of EPA regulations on the chemicals and processes used in hardening-or so I've heard.
That said, it is easy to destroy a new camshaft on initial fire up primarily due to a lack of sufficient lubrication for the first few critical minutes. I have ceased using crankshaft wipers because they restrict oiling of the camshaft. I would never use one with any "slip & slide" lifters and be very wary using one with roller lifters. My Father has had such trouble with modern camshaft lobe failure that he will not guarantee any engine he builds unless it is roller lifter equipped.

[This message has been edited by sunocospecial (edited 06-19-2002).]
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post #8 of 18 (permalink) Old Jun 20th, 02, 02:25 AM
 
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Make sure it's the valves. I once thought it was the valves and replaced the lifters twice. And all the time it was an exhaust leak.
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post #9 of 18 (permalink) Old Jun 20th, 02, 06:12 AM
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Check to make sure the rocker arms or anything else isnt hitting the valve covers. I had a couple rockers hitting (the pushrod side) was slightly hitting the inside of the valve covers. I could hear it and I used a hose and a stethesscope to find it. Its worth a look.

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post #10 of 18 (permalink) Old Jun 24th, 02, 05:17 AM Thread Starter
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Update...autopsy nearly complete...thought I'd post my findings.

After much effort, deliberation, and consultation, to solve this prob,...

I pulled the engine and took it apart. I knew I had problem when I couldn't get the #7 exhaust lifter out of it's bore.

I slid the camshaft out and sure enough, I wiped out a lobe...the #7E. The lobe had a pyramid shape off to one side and the lifter was bowled out pretty bad. I've never seen anything like it.

The other lifters and lobes looked ok, though I only inspected visually.

Now to learn why...why this happened on a mild cam with mild spring pressure. An engine builder friend thinks something in the shortblock caused this...spun bearing or something. I guess I'll take it apart as long as it's on the stand.

Thanks for your help anyway.

PS...need a loan.

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post #11 of 18 (permalink) Old Jun 24th, 02, 07:27 AM
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I hope you dont think I'm some kind of ******* cause I know you're having a hard time. You said "now to learn why". #1 Break the thing in with only a single spring like comp reccomends. #2 use the assembly lube they provide. Put a ton of it on no matter how messy it is. #3 hopfuly the cooling issues are gone I talked to Comp when I had a loud lifter and they asked me if it was in the back of the motor. It was. they said thats common because those aft lobes sometimes dont get as much oil sling off the crank because the oil pump sometimes blocks it. Get a big fan to put in front of the car (radiator) during breakin. Run it at the RPM and for the 20 to 30 minutes Comp says. Good luck this time, I know how you feel.

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post #12 of 18 (permalink) Old Jun 25th, 02, 02:27 AM
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I feel for ya too buddy!!! just went throuh/am going through same thing with comp cams in my BB.

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71 BB SS Chevelle (clone)
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post #13 of 18 (permalink) Old Jun 25th, 02, 04:28 AM Thread Starter
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Brother HotRod69Camaro,...I appreciate the input but I disagree with some of your suggestions.

1) A mild cam should survive 120# of seat pressure and 310# open during break-in. My springs happen to be dual, but many springs in this mild spring-pressure range are single.

2) I used the red break-in lube on the lifters supplied by Comp Cams...the little packets. The cam (and the rest of the short block) was lubed with ARP's assembly lube. Again, I'm less than impressed with the Comp Cam's stuff...too viscous, not "pasty". Most the CC stuff will drip away before the motor is on the sling. But I don't think this caused my problem.

3) Cooling issues? Idle a freshly built 406 small block at 2000-2500 for 20-30 minutes and watch the temp climb. Mine did with a Stewart Stage II water pump, 160 degree stat, and 3 core 23 inch radiator, and huge box fan blowing through the grill. I shut her down ten minutes into break-in, but I can't believe that contributed to scrubbbing off a lobe...like I said, I started to hear clacking five minutes into my initial start-up.

But, in the future, it might be wise on a 406 to remove the stat completely during break-in and run a garden hose to the radiator...open the drain-**** on the radiator and introduce a little cool water into the cooling system (too much cool water might crack the radiator).

Those are my thoughts...any other ideas?

Also, it appears the lower part of the motor is fine. I'm going clean out the oil pump and take the oil pan to be dipped to remove any shrapnel. Do I need to do anything else to remove bits of my #7E lobe from the short block (or heads)?
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post #14 of 18 (permalink) Old Jun 25th, 02, 05:09 AM
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Sleepy I spun the oil pump with a new filter and fresh oil to get anything out of the inner passages. Do a search on my username for more details if ya want.

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67 prostreet BB Camaro
71 BB SS Chevelle (clone)
2002 35th anniv SS Z28 conv.
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post #15 of 18 (permalink) Old Jun 25th, 02, 07:31 AM
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Sleepy I know you got plenty of blood sweat and tears invested in this mill as well as plent of $$$$$, and I'm having a hard time understanding why go against the manufactures recommendations. Thats what came to my mind when you said lets see what we have learned.

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