Flat tappet cam failure

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Jun 16, 2009 | 08:52 PM

markey mark

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Flat tappet cam failure

Anybody experience a quick cam failure? Got about 4 hours run time on my rebuilt motor with flat tappets and I've got alot of noise somewhere. Definitely not the power stuff on front of the motor, I've pulled off the alt,power steering pump and a/c compressor. Almost sounds like a rod knock, but can't really tell. Motors out of warranty by about 6 weeks too. Seems to run fine with little noise at start up but gets worse when things warm up, about 5 minutes. Could this be the dreaded premature flat tappet cam failure? Got the right break in oil in it too.

Jun 16, 2009 | 09:04 PM

longbros

Burning Brakes

Joined: Feb 2004

Posts: 924

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From: Kearneysville West Virginia

I had a Pontiac 400 that was quiet when started cold, but as it warmed up, it started knocking. Turned out to be a rod knock.

Jun 16, 2009 | 10:28 PM

Budman68

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From: DFW TX

Cruise-In VII Veteran

St. Jude Donor '07

Have you pull the valve covers to check for a loose rocker? Check the easy stuff first, before you panic. One of my lifters didn't pump up and it made all kind of noise. One push down on the rocker and it pumped up, problem solved.

Jun 17, 2009 | 07:57 AM

bashcraft

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From: Butler Pa

What is the oil pressure like?

Jun 17, 2009 | 04:28 PM

markey mark

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Oil pressures good. Will be pulling the valve covers off as soon as I get a chance.

Jun 17, 2009 | 09:40 PM

narlee

Melting Slicks

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From: Western Washington

What oil are you using?

Jun 18, 2009 | 08:46 PM

markey mark

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Got Royal Purple Break-in oil in as per the engine rebuilder. Almost sounds like detonation, gonna retard the timing some and see what happens, only about 10 degrees now tho.

Jun 18, 2009 | 09:26 PM

PeteZO6

Drifting

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From: Cameron Park CA

An easy test for a wiped cam lobe is to take the valve covers off and start the engine. The pushrods should all be rotating. Any that are not rotating indicate that cam lobe is bad.
Lifters are not perfectly flat on the bottom, they are ground with a slight concave surface. The cam lobes are tapered very slightly also, so the edge of each lifter rides on the high side of the taper, resulting in the lifter rotating. It's done on purpose so there is not a pure sliding interface between the lifter and cam lobe, but more of a rotating one so wear is much less.