How long should a flat tappet cam with 100# valve springs last?

[V6 Beast]

I had a new engine rebuild done right before Bristol last year and pull my intake yesterday and can see that 3-4 cam lobes are worn down severely. May explain why I ran 10 MPH slower this year. I only drive my car couple days a week on street and run it 4-5 times a year at track so I have less than 5000 miles total since new cam. It seems a bit premature. What could cause a cam to wear so quickly?? Thanks for any insight.


Sully

 

[TurboDave]

Generally improper break in is what causes it. An additional factor is how well the cam is actually made, etc.

I've got just over 30,000 on mine and no problems yet (knock on wood).

 

[GNSCOTT]

My engine builder told me once that crank makes its first rev. the cam lube is gone. He told m it is best if you hooked everything up right and the car immediatly fires up, also i hear of alot of people and some vendors going to 90# springs because of this.

 

[750H.P.V6]

Sully,

I'm going to have to go with Turbo Dave on this one. Proper camshaft break in is critical in determining how long the cam will live. Since you stated you have several lobes going flat this normally points to improper break in.

The problem is that many poeple go to start their new engine without having everything checked to ensure the car will fire off on the first try. A few things that need to be checked are cam sensor setting, pre-oil the motor, prime the fuel system etc.

Normally a 100# spring won't generate enough "open" pressure to be detremental during camshaft break in. There are instances such as solid flat tappet applications where break in with a softer spring is recommended but this application doesn't qualify.

I hope this helps

Neal

 

[NCTURBOS]

2 things...

1.) What'd I tell you when you were starting to build the motor? (Roller!)

2.) I figured that was the problem. Was just waiting for you to pull the intake.

You gonna have it back together by Reynolds or Mooresville?

 

[Nick Micale]

Don't know if this will qualify as "insight" but we have looked at a few failed Buick cams. The others that examined them with me are very experienced in race motors both in building and tuning. The premature cam failures which happened within a few thousand miles or so, all so all indicated a bad core. Mainly the heat treat, hardening process, was not done properly or deep enough.

One in particular we know was broken in "by the book" was showing signs of wear in less than 1000 miles. Lifter looked fine, lobe was worn and had small imperfection on the surface. This was certainly NOT due to spring pressure [~100#'s], but a bad core.

We do a 20-30 minute break in run, but within a few minutes the lobe and lifter become acquainted! Like was already said, cam lube is gone, so they are on their own from there for better or worse.

Few years ago, there was a rash of aftermarket Buick cams with low mileage problems and most were found to be a core problem. Some people have said the lifter bore alignment is off on some blocks. But if it runs fine for 100K miles or so on a stock cam, and 1000 miles or so on a replacement cam, would seem no block problem?

As far as an answer to your original question, think I would direct it first to the cam supplier/manufacturer.

This is strictly my opinion, but I feel the "improper break-in" reply to a bad cam is voiced so much from the suppliers/manufacturers, that it has become "the reason". Second excuse, "wrong valve springs". They would NEVER put out a "bad" product!

 

[laz]

I remember talking to you at Bristol . I run 100 lb springs on Roy Garcia`s car and have never had a problem. I broke in the motor in with 100lbers and have never had any valvetrain problems and it`s been together 2 years . What cam you running? B.T.W. i would pull the motor, your bearing are almost sure to be trashed,check the turbo also. Laz