I'm looking around trying to find the symptoms of a cam with flat lobes. I think i goofed when i re-assembled my engine and it took the cam out. Would i be looking for a rough, lope like idle? Or just backfiring/missing and a constant rich fuel smell? My truck has a few of these symptoms... and i'm just curious.

Thanks Ya'll

 

Yeah, it'll run rough and you should lose power too.

If you want to do a relatively simple check, pull your valve covers, press down on each rocker with a screwdriver or similar item.

A bad cam lobe will not force the screwdriver back up it'll kind of float or just sit there.

 

I've also heard that the push-rods won't spin in their holes if a cam lobe is flat. And i'm having symptoms of this on about 8 of the 12 pushrods.

Guess i'm lookin for a new cam huh?

 

Take a look, if you can, and see if the lifters are spinning. That's what counts. I've got pushrods that dont spin in my 390, but the lifters are down there spinning away...

 

Well the whole reason for this thread was the fact that my 300 has a rattle that will not go away. The engine is quiet while cold, and will not rattle while not under a load. Only after the engine is warm and i'm driving it down the road will it rattle. Though it usually doesn't do it at just any rpm/speed it mostly does it above 55mph. The noise is so loud i can hardly hear myself think. I know it isn't rod knock...and i've played with the valvetrain once or twice and gotten it quiet..but the sound keeps returning.

For all i know the cam may be fine.. and the rocker arm studs could be pulling out and causing all the problems...

 

desperado,

Are you talking about "valve chatter"? That sounds like a bunch of ball bearings in a bucket if you shake it.

That "could" be solved by RETARDING your timing a few degrees.

 

Timing is set at factory 10*. I'm certain it isn't pinging... its definately in the rockers. Like i said i can adjust the rockers and it'll go away. So i'm certain it isn't that.

I just wish there was a deciding factor that would say definatively it was the cam, or the studs in the head had been pulled up by me over tightening them or something.

 

There is a way to check cam lobe wear by removing the valve cover, collapsing the hydraulic lifter by putting pressure on the valve push rod, and measuring with a dial indicator. I've done it, but it has been so long ago that I can't remember the details. It's worth doing before giving up on your cam. It is how I found out that mine was bad after chasing a mysterious miss for over two years. Good luck.

 

i think im having this problem. It misses fire and backfires through intake under a load.