Flat cam - Team Camaro Tech
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post #1 of 9 (permalink) Old Feb 10th, 10, 08:58 PM Thread Starter
Kelly
 
Join Date: Feb 2010
Location: SW Washington
Posts: 9
Flat cam

I have a 454, near as i can tell it is a 71-79 truck block. It has valve train noise on passenger side. I asked a friend of mine about this and say's they are notorious for the cam lobes going flat. ecspecially in #6 & #8 cylinders. Has anyone else ever experianced this? what did you do correct the problem beside replacing the cam and lifters? Any advice is appreciated. Thanks
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post #2 of 9 (permalink) Old Feb 10th, 10, 09:23 PM
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Ron
 
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Re: flat cam

1st of all it's common sense to inspect the area from where the noise originates.

Take the valve covers off, start the engine and observe the Valve train. Use hands with a hardwood stick to feel for slack. You are looking for broken rockers, springs, bent push rod, failed lifters or lobe (Push rod not spinning) ... etc.

Replacing broken valve train parts should not take an experienced person more then 20 minutes per cylinder to replace the damaged parts such as worn Rocker Nuts, Studs, Rockers and adjust accordingly. If this fails you may have a Lobe issue.

If the engine is Hi-Mileage and compression is good, you are probably due for Timing Gear and Cam replacement, water pump, fuel pump, rad ... etc.

If the engine has made it this far without issues you better off diagnosing problems then with a fresh rebuild.

I have no clue what you know about engines but I've provided you with the first step. The average motorists has no idea that their engine has a wiped lobe other then; if it runs, it's just fine - That is, until it STOPS and then it's too late for conventional maintenance; other words, you're one step ahead just by being here.

PS: Your friend has a misconception and GOOD LUCK ;o)

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Last edited by Z15CAM; Feb 10th, 10 at 11:48 PM.
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post #3 of 9 (permalink) Old Feb 11th, 10, 07:38 AM
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Rich
 
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Re: Flat cam

Just as a side note,if it is more of a clucking sound at idle,the late 70's 454'swere notorious for piston noise.I ran 2 different tow vehicles with this noise and never corrected it.One had over 200K and the other well over 300K and that one broke a timing chain and was never right after that.The cluck was never an issue for them.
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post #4 of 9 (permalink) Old Feb 11th, 10, 12:41 PM
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Ron
 
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Re: Flat cam

Rich: Yes I've come across "Piston Slap" in Hi-Mileage 454's as well. It's unbelievable how slippery (loose) the Piston to Cylinder bores can get and the cylinder bores can look like this " ) ( " - LOL

For this reason when I rebuild, I place the Oil Ring Gaps to the Thrust Side hoping the Oil Trace will help eliminate this wear. I believe GM off sets the Wrist Pin .020" for this very reason.

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post #5 of 9 (permalink) Old Feb 11th, 10, 07:59 PM
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jeff
 
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Re: Flat cam

Quote:
Originally Posted by butternut1972 View Post
I have a 454, near as i can tell it is a 71-79 truck block. It has valve train noise on passenger side. I asked a friend of mine about this and say's they are notorious for the cam lobes going flat. ecspecially in #6 & #8 cylinders. Has anyone else ever experianced this? what did you do correct the problem beside replacing the cam and lifters? Any advice is appreciated. Thanks
GM cams of that era (mid-late 70's) were the weak link. What is now considered 1/2 life of an engine (125,000 miles) the cam and lifters were usually junk. The lifter faces would wear through and the lobes would be near flat so (just my opinion here) yes I believe your friend. I had 2 vehicles that happened to during that time period. I have a 3rd sitting in my shop right now (my 1-owner 75 Camaro). It has 157,000 documented miles with all receipts. Good compression and no knocking or ticking but the cam is almost flat on multiple lobes.
Replace the cam and lifters (timing set also) and keep your eyes closed when it comes to the rest unless you intend to run it hard It's not a problem inherent with the 454, it was a byproduct of the 70's.

Jeff.
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post #6 of 9 (permalink) Old Feb 11th, 10, 08:46 PM
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Tom
 
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Smile Re: Flat cam

Make sure the noise is not just a loose rocker. Unless it starts backfiring, or low on power, I wouldn't worry about it.

69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1
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post #7 of 9 (permalink) Old Feb 14th, 10, 04:42 PM Thread Starter
Kelly
 
Join Date: Feb 2010
Location: SW Washington
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Re: Flat cam

Thanks Guys. I have not done a compression test yet but i will this week. The car has very ltittle power. With a big block/4 spd it should run pretty good.
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post #8 of 9 (permalink) Old Feb 14th, 10, 09:32 PM
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Jimmie-Retired
 
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Re: Flat cam

I've had 2 higher mileage big blocks and both developed piston slap. I would only notice the piston slap when the engine was "under load". If you're engine is doing it at idle, I'd guess that it's just valve train issues. You've recieved good diagonistic tools from X51cam and others. I believe the other suggestions have covered all the bases.

Jim's '69
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post #9 of 9 (permalink) Old Feb 14th, 10, 10:19 PM
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AJ
 
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Re: Flat cam

When is the last time you replaced the exhaust gaskets, checked lash, and re-torqued the exhaust manifolds/headers?

The only Mustang I'd ever own is a Fender.

'68 333" Camaro
'14 5.0 Mustang
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