i just rebuilt my 400 and put a new cam i started it the firts time and i didn't have timed right so i stoped the motor and timed it right when i told my frend that he told me i need a new cam because i didn't start it and rev it at 2000 rpm for 15 mins to break it in is it true

it has 1000 km and seem to run fine

 

The first 20-30 minutes of running time are critical for proper break-in of the cam lobe/lifter interface. If you don't follow the cam manufacturer's recommended break-in procedure, you dramatically increase the risk of premature cam or lifter failure. The engine might seem to run fine for a while, maybe up to 20-30K miles, or maybe only a few thousand miles. Or you could even be lucky, and never have a cam failure.

The most common failure caused by improper cam break-in is accelerated wear on cam lobes/lifters. Worn out cam lobes and lifters will cause a gradual decline in performance (which you might not notice at first, but it will continue to get worse), and eventually, repeated incidents of bent pushrods as the valve train slack (or lash) increases.

Sometimes, excessive heat generated by friction between the cam lobes and lifters will result in a broken camshaft, but that's not common.

If you can keep the engine running at all for 20-30 minutes after the initial start-up, you should run it and defer any tuning adjustments until after the cam break-in.

If you absolutely have to stop the engine (for a major fluid leak or some other catastrophic failure) before you complete the cam break-in, you should resume the cam break-in procedure as soon as you get the engine running again.

BTW: You should use the same type of break-in procedure whenever you install new lifters on an existing camshaft.

 

Drain the oil into a clean pan and look for dark stuff settled in the bottom. AKA finely ground lobe material.

 

ill drain the oil and look this weekend

 

my dad has rebuilt lots of motors hipo and normal and he has never done the cam break in and there still running.

 

Always, always, always be sure to break in the cam. My family has been racing for a long time and the motors we build we always break in the cam. It doesn't take long and it save you alot of hassle down the road.

Sanders

 

ok what does the cam breakin do to the cam that just driving it doesn't

i don't know about you guys and gals but i don't like the idea of starting a motor and reving it to 2000 rpm with out leting it warm up, and when its new id think thats a real no no

 

The idea behind running the engine at 2000 RPM is to bring the oil pressure up to it's highest level to provide maximum lubrication while the cam & lifters are establishing a "good working relationship."

On initial start up with a new cam & lifters or even just new lifters, the lubrication is provided by the assembly lube. If you don't get good oil pressure to the cam & lifters quickly there can be excess wear from the metal to metal contact between the cam & lifters which will result in a "wiped lobe" because the lifter wears right through the hardened surface of the cam lobe. Good break in procedure allows the cam & lifters to establish a wear pattern that distributes the load across the surface of the cam lobe and reduces wear on any one area of the lobe.

Engine oil pressure at idle is very low, even on a newly rebuilt engine and the absolute worst thing you can do with a new cam is allow it to idle for extended periods of time after initial start up. Unfortunately the first thing you want to do when you start a new engine is to set the timing up, check for leaks, crack open a beer to celebrate, etc. with the engine idling. If you have a relatively mild build you might get away with it but especially on engines with performance cams & stiffer valve springs you're running a big risk of ruining the cam or at least severely shortening it's life by doing this.

Obviously driving it is better since you're increasing the oil pressure but it's still best to use the proper break in procedure recommended by the cam manufacturer. Most tell you that improper or no break in will void the warranty.

 

ok if it did do what you guys said it will it is to late so if i have to get a new cam before i have to rebuild the motor i'll do the breakin but if i dont ill just think of it as a myth

 

It's really no myth. The lifter are supposed to rotate and are offset slightly on the cam lobe to facillitate this. At idle they may not turn on a new engine and that wipes off the lobe before the wear pattern is established. 2,000 rpm will get everthing bouncing around and rotating. Also gets the oil splashing around.