Camshaft failure...
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Pro
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From: New York
Camshaft failure...
With all this talk about camshaft failures-[flat tappet]-due to low levels of zinc can someone explain to me what would the symptoms of a camshaft failure be... Thanx...Jerrylee///
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Joined: Dec 2007
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From: Columbus GA
oil companies have used zinc based additives in oil for +50 years for metal on metal rub. since most all cars and trucks have had a roller valve trane for the last 20 years and the zinc additives clog catalitic converters, they just removed the additives. there was alot of influence from the EPA and the oil companies did not warn anyone.
Burning Brakes
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Racer
Joined: Dec 2004
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From: Wichita Kansas
Most cams have a nitrided surface. This is a very hard layer RC 60 to 62 but very thin about .005 in. Once the lifters wear through this the cam wears out fast. I know, I had and engine fail from this. The car starts loosing power and the rocker arm clearance increases as the cam wears. All that metal getting into the oil can ruin the engine.
Le Mans Master
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From: Little Rock AR
The symptoms can include backfiring into the intake under load that seems to come out of nowhere and quickly gets worse. At cruise it usualy seems to run fine. This problem generaly gets worse in a hurry once the lobes start to go bad but that is not a given. Some times it will run a lot longer.
-Mark.
-Mark.
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From: New York
Thanx a lot for all the replies guys...The reason I ask is I have a flat tappet in my rebuilt engine-[XE268]- and with all this talk I wanted to be aware.....Right now I have about 3,000 miles on the rebuild n she's running real strong..Thanx again...Jerrylee///
Racer
Joined: Jan 2005
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From: In the shop most of the time,,, And it BEER TIME somewhere
Read these links from Comp Cams, good information. http://www.compcams.com/information/...yID=1985582846 http://www.jbp-pontiac.com/techDoc/C...ilAdditive.pdf 
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From: New York
So is it safe to say that once your engine is broken in your camshaft is broken in.....The tech from Comp told me that if you are going to have a problem it will most likely occur right away but yet a friend on the web told me his engine went around the 20,000 mark n his mechanic claimed it was due to improper cam breakin...So which is it...Thanx...Jerrylee///
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From: eville in
So is it safe to say that once your engine is broken in your camshaft is broken in.....The tech from Comp told me that if you are going to have a problem it will most likely occur right away but yet a friend on the web told me his engine went around the 20,000 mark n his mechanic claimed it was due to improper cam breakin...So which is it...Thanx...Jerrylee///
Le Mans Master
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From: Las Vegas - Just stop perpetuating myths please.
It can happen to nearly any brand flat tappet cam.
Jerry my cam wiped #3 exh right on cam break-in. It started ticking just as i finished 20min @ 2000rpm.
Pulled the vlv cover and i could turn the rocker nearly 360* around by hand. Few weeks later #4 intk followed but not as drastic. I could not believe this and thought it was bad rocker nuts but once i pulled the intake i found 3 wiped lifters.
My advise:
-do not turn engine over with starter anymore than absoute nessesary until cam break-in. Low rpm rotation kills the new lobes & lifters by preventing lifter rotation and causes wear pattern in only one direction.
-use weaker springs (heck old stock spring will do) for cam break-in using low (1.5) ratio rockers.
-use GM break-in lube.: :
-break in cam immediatly to 2000rpm for the first 20min.
Good luck,
cardo0
Pulled the vlv cover and i could turn the rocker nearly 360* around by hand. Few weeks later #4 intk followed but not as drastic. I could not believe this and thought it was bad rocker nuts but once i pulled the intake i found 3 wiped lifters. My advise:
-do not turn engine over with starter anymore than absoute nessesary until cam break-in. Low rpm rotation kills the new lobes & lifters by preventing lifter rotation and causes wear pattern in only one direction.
-use weaker springs (heck old stock spring will do) for cam break-in using low (1.5) ratio rockers.
-use GM break-in lube.: :
-break in cam immediatly to 2000rpm for the first 20min.
Good luck,
cardo0
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From: eville in
Burning Brakes
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From: Scottdale Pa
Just this summer in June my 18k mile L48 cam went bad, Gm 350's of the late 70's and early 80's were notorious for premature failure. I decided to do the whole top-end and used a CompCams xe268 that wiped out 3 lobes on breakin. CC did replace the cam, but from what I've read since then, the XE line of flat tappet cams have been a problem on break in and are very noisey. So I went with a Magnum 270H. So far so good at about 1200 miles.
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From: New York
Thanx 4 the advice Cardo but I'm already around 3,000 miles into my newly rebuilt engine...n like Crabvette I'm using the xe268 but for the BB...As stated earlier up till now she's running great but I guess your never safe...Thanx again...Jerrylee///
