Noise in valve train? - Team Camaro Tech
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post #1 of 19 (permalink) Old Nov 9th, 11, 07:28 PM Thread Starter
 
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Noise in valve train

I have a 388 small block with about a 1,000 miles on it,solid roller,640 lift cam. I have some type of tapping sound that comes and goes,I checked all valve springs,valves,retainers,pushrods.the only thing that I have not checked is the litters.I can't pinpoint where the noise is coming from,it almost sounds like its coming from under the intake,it's not consistent,it's intermittent and does not get any louder when raising idle.This tapping noise sounds similar to a pre-ignition knock,,any suggestions on what this might be?or what else to check before I pull the intake off?
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post #2 of 19 (permalink) Old Nov 10th, 11, 05:56 AM Thread Starter
 
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Noise in valve train?

I have a intermittent tapping noise in the motor,can't tell where it's coming from.It almost sounds like it's under the intake and doesn't get any louder when I increase idle,kinda sounds like a pre-ignition knock.
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post #3 of 19 (permalink) Old Nov 10th, 11, 06:24 AM
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Re: Noise in valve train?

If you have a manual fuel pump check it with a long screwdriver with the screw end on the pump and the handle on your ear.

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post #4 of 19 (permalink) Old Nov 10th, 11, 06:26 AM Thread Starter
 
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Re: Noise in valve train?

Thanks I will do that.
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post #5 of 19 (permalink) Old Nov 10th, 11, 06:48 AM
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Re: Noise in valve train?

Flat tappet cam? Wiped out cam lobe?

Need more engine info.

Remove valve cover(s) and turn engine over, watching the rocker arms. Make sure none of them have less travel than the others.

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post #6 of 19 (permalink) Old Nov 10th, 11, 07:49 AM Thread Starter
 
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Re: Noise in valve train?

1,000 miles on motor,solid roller 640 lift,everything new except cam,had engine built around cam.The motor is a stroked 388,also I believe engine builder also used same lifters.The motor was built at the end of 08 and I only drive it maybe once a month that's why it has little miles on it.I don't know if this means anything but I just went from conventional to synthetic oil before this noise occured.(coincidental maybe?)
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post #7 of 19 (permalink) Old Nov 10th, 11, 08:32 AM
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Re: Noise in valve train

the first thing i might check is to see if the valve spring or retainer is rubbing the rocker arm underneath--check roller bearing on rocker arms-valve adjustment ect. is the rocker arm tip setting directly over valve stem--is the geometry correct--rocker tip riding in middle of valve stem--i would also change oil and filter--after all this is checked might have to pull the intake
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post #8 of 19 (permalink) Old Nov 10th, 11, 08:33 AM
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Re: Noise in valve train?

check your post in performance
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post #9 of 19 (permalink) Old Nov 10th, 11, 08:37 AM
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Re: Noise in valve train?

Quote:
Originally Posted by 97Z4C View Post
check your post in performance
Both threads have been merged and moved here to Troubleshooting...

...Dennis

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post #10 of 19 (permalink) Old Nov 10th, 11, 09:07 AM
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Wink Re: Noise in valve train?

1st, DO NOT double-post
Dennis fixed it for you this time.

2nd, what year/type of block is it and what kind of cam locating device and drive are you using with the roller system?

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post #11 of 19 (permalink) Old Nov 10th, 11, 09:52 AM Thread Starter
 
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Re: Noise in valve train?

Let me start from the beginning and I hope it's not to much info!I had this engine built in 08,it has approximately 1,000 miles on it now.I drove my car to a car show,when leaving the show I heard this noise.when I got home I pulled the valve cover off and noticed that I didn't have any clearance between the rockers and the retainers so I took the car back to the machine shop were the engine was built,the guy who built it is no longer there due to a terminal illness.The owner of the shop looked at it and told me that the retainers are bad,come to find out when he redid my heads from top to bottom he re-used the retainers which were titanium,now that it's been 3years he won't stand behind his work!I found out that titanium retainers are not good for street applications because of hot and cold temps makes them soft.I was able to contact the guy who built the motor and he told me to go to a steel retainer so I did,then i got coil bind and still no clearance,found some bad rockers also.I just purchased new comp ultra roller rockers 1.5 and put those on,still no clearance!I was told to remove the shim (.030)from each spring and go from a 10 degree keeper to a +.050 so I did that,that fixed the coil bind problem but I still have almost no rocker retainer clearance and I still have that knocking noise.
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post #12 of 19 (permalink) Old Nov 10th, 11, 10:01 AM
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Wink Re: Noise in valve train?

You just answered your own question then
Problem is most likely retainer bottoming on head/seal or maybe even coil-bind on some with shimming.
Is the rocker geometry correct - valve stem contact patterns good - pushrod length(s) correct for your valve train?
That's a lot of lift for a reliable street engine, things have to be correct for it to last ...

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post #13 of 19 (permalink) Old Nov 10th, 11, 10:18 AM Thread Starter
 
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Re: Noise in valve train?

When the springs were removed the seals were perfect,I don't have coil bind now but still very little clearance between the rockers and the retainers,what other options do I have (pushrod lengh?)the motor is a 1972 350/40 over 4bolt main and as far as a cam locator device,it has a cam button if that helps any.
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post #14 of 19 (permalink) Old Nov 10th, 11, 11:07 AM
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Re: Noise in valve train?

Quote:
Originally Posted by Sick1 View Post
... what other options do I have (pushrod lengh?)...
Yes, the pushrod length may be to short for you stack-height.
Installing a longer pushrod will move the pivot point of the rocker higher and give more clearance at the retainer.
You'll need to get an "adjustable" pushrod (like the TFS-9000 - http://www.summitracing.com/parts/TFS-9000/ or the Comp 7701-1 should work fine for your needs.) and do a geometry check of a couple intake and exhaust locations to see which length(s) you need to order for the best operation. This is taking for granted your original machinist installed all the valves at the same spec. height ...
(note: every time you make a change - rockers/retainers/etc... - to a HP valve train you need to re-check the geometry to be sure it all still 'stacks' the same.)

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post #15 of 19 (permalink) Old Nov 10th, 11, 01:01 PM
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Re: Noise in valve train?

I wondered where this thread went.

Did you drive it for those 1000 miles with the coil bind problem? Bend any pushrods? Find any loose rockers? What was wrong with the rockers you said went bad? How much open pressure on those valve springs?

Just by the way you described the knocking sound I keep thinking it wiped a lobe or two. When mine ate the cam it sounded exactly as you described. The noise sounded like it was coming from under the intake or inside the head, and sounded just like a pre-ignition knock. In fact, that's what I thought it was at first.

I'd start with turning it over and checking the rockers for equal movement.

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